Science Down Under

This week, we head down under to explore the latest Australasian science - we'll discover the new, state-of-the-art facility where high-tech lasers and cameras breed the best...
22 November 2009
Presented by Chris Smith


This week, we head down under to explore the latest Australasian science - we'll discover the new, state-of-the-art facility where high-tech lasers and cameras breed the best plants; explore a new remedy for wine ruined by bush fires and find out why grapes killing themselves is the tip to a wonderful tipple. We also reveal, two new bowel-bugs that cause gastroenteritis and why porridge is good for your guts. Plus, we investigate the best temperatures for serving wine, in Question of the Week!

In this episode

Arabidopsis thaliana - thale cress

00:53 - Remote Monitoring of Plants and Keeping an Eye on Salinity

We learn how to monitor plants using conveyor belts in one of the world's biggest greenhouses, plus how scientists are trying to solve the problem of increasing soil salinity...

Remote Monitoring of Plants and Keeping an Eye on Salinity
with Mark Tester, University of Adelaide

Mark Tester is professor of plant sciences at the University of Adelaide's Waite Campus where he's building a new facility to root out what makes plants do what they do...

Mark -   You know the advances in genomics. Roaring ahead, we can sequence genomes.  We can manipulate genomes.  We can do extraordinary things with molecular biology.  What's starting to fall behind in science, especially in plant science at least, is the ability to measure the effects of those manipulations on the whole plant performance, the growth, and how the plant works when it's fully grown.

So what we need to be able to do is characterize the effects of those manipulations, the growth of the plants in controlled conditions in a high throughput and efficient manner.  And that's the driving force behind this new construction we're going to describe.

Chris -   Well, set the scene.  Is this the world's biggest greenhouse?  It looks like it!

Mark -   It's not the world's biggest greenhouse but it's the world's biggest greenhouse of this type.  What we've got here isn't just a greenhouse.  I mean, it's a very impressive greenhouse, but it's a greenhouse that is going to have a large portion of its floor area covered with conveyor belts, and the plants will be moved both dramatically on the conveyors to imaging stations where we'll be using remote sensing technologies to monitor the growth and some aspects of the performance of the plants.

Chris -   Why is that helpful?  Can't people just walk around and look at plants, anyway?  Why do you need that to do it?

Mark -   Yeah, of course.  We can go around and look at plants, but there's two things: humans are quite slow and expensive.  And the other thing is they're notoriously biased in they're looking in their observations and not quantitative.  So we're getting objective, quantitative measurements of the way the plants look.  Also, with the technologies we're using, we're not just using visible light.  We're peering into some of the hidden parts of the plant, what they're doing in the infrared spectrum, how they fluoresce when we irradiate them with ultraviolet radiation.

Chris -   So basically, you've got an infrastructure here which means that you can grow plants under very strictly defined conditions.  Every plant's going to get the same conditions, and it's going to get assessed in the same way.

Mark -   That's exactly right.  So when we grow in here, a population of 50,000 plants which we could do for some of the smaller plants, we can have them being automatically measured, non-destructively through time.  So, the fact that we're not having to kill the plants and weigh them is another very important feature.  And this opens the door for a whole range of genetic studies.  It's bringing more genetics into physiology, more physiology into genetics.  And if we bring those two fields together, plant science is going to really get a big kick.

Chris -   What sorts of questions will you be able to ask them?  In what way will you be able to take plant sciences forward with this?

Mark -   We can ask questions in two ways.  One is to get a gene that's identified and start to ask questions that, what that does to the plant's performance in a quantitative and objective way.  The other way, which I think is more powerful in many ways, is what's called a genetic approach, a forward genetic approach, where we can get plants that have got different properties, and start to ask the questions, "What gene is responsible for that difference?"  And then we can have a plant that keeps growing well in a salty soil and another plant which dies or doesn't grow as well on the salty soil.  What genes are responsible for those?  So you're asking the plants the question.  Like, "You're tolerant.  Why are you tolerant?"  And the plants tell you the answer rather than try to sit there and be smart, and say, "Oh, I think it's that gene."  And waste your career doing that.

Chris -   Which will be bad.  Is this the first of its kind in the world, then?

Mark -   This is the first of its kind in the world.  There's one smaller version in Germany.  And there's a couple of slightly different and smaller versions in the private sector, but this is certainly the first to have so many wavelengths, looking at the plants, and certainly in the scale and in the public sectors.  So any scientists in the world can come and use this and benefit for their particular scientific questions from this facility.

Chris -   What sort of floor area will you have?

Mark -   It's four and a half thousand square meters of building, and there's over a arabidposiskilometre of conveyor belts delivering the plants.  So if we have a large plant, like a wheat plant or a sugarcane plant, or a little tree, we can measure those sorts of plants because it's a very tall greenhouse.  We're able to measure something like two and half thousand plants at any one time.  If we're looking at little plants, we could measure 50,000 plants.  And given, you know, in the arabidopsis genome, and a lot of plant genomes, has 25 to 30,000 genes, you can start to look at the effects of knocking at every gene in the genome all at the same time.  I think that's quite powerful.

Chris -   What about the fact that you're going to have very large numbers of plants all together? How are you going to keep pests at bay and that kind of thing?

Mark -   That's a good question.  The air in every greenhouse room is completely separate from the air in every other room.  And so, we've actually spent $4 million just on the air conditioning for this building.  A quarter of the cost of the building is on controlling the airflow.  And one of the main reasons for that, besides defining the environment, is to minimize the pests.  I think every room has its own air control in and out, isolated.  So that reduces the spread of the pests. And we have of course a monitoring and spraying regime which will be in place.  We use biological control.  And the other thing, because not only there are lots of plants here but they're moving around on conveyors.  That's dangerous.  So we've got a little spray station.  So, as the plants come out from their imaging, they go through a little spray station and get a shower to clean them up.

Chris -   And if there's a power cut?

Mark -   We're generating our own power, which actually saves a lot of CO2 emission surprisingly.  The substrates got good gas, good gas supplies, and so we can pipe in the gas, and generate our own electricity.  We generate about 70% of our own electricity on-site.

Chris -   Can you send the fumes from the generator through the greenhouse to get the plants to soak up the CO2?

Mark -   Yes, you can.  We can use the CO2 for controlling CO2 levels in the greenhouse because of course, studying the effect of climate change on plants is very important.  So we do have a high CO2 capacity.  We use the fumes also for - we extract the energy from the fumes before they leave the building to heat water and heat air as necessary.  So, yeah.  It's great.  It's called a tri-generation system.  You get three bangs for one buck.

Chris -   What about water?  Presumably, you can collect all the water that runs off and put that in tanks, but there's going to be some thirsty plants here.

Mark -   Yes.  We're able to supply most of our own water supplies from the rain.  We're storing a third of a million litres of rainwater.  But inevitably, we will need some Maine's water as well, unfortunately.  We're recycling all our water.  So, 90% of the water is recycled and I'm proud of that.  And the main problem isn't the plants.  We've got enough water for the plants, pretty much.  The main problem is the electricity generating plant that we've got.  That uses a lot of water.  That uses a couple of million litres and we can't service that.  So that's going to have to use Maine's water, unfortunately.  But we're still trying to recycle as much of the steam as possible that's lost from there.

Chris -   More from Mark Tester later. 


Chris - Back to Mark Tester now and how he's helping to solve a major problem that farmers are facing now and in the future, increasing soil salinity.  Salt doesn't give plants high blood pressure, but it does lead to an early death.

saline soils in coloradoMark -   The main application from our research is to improve crop production around the world.  We all know, we need more food and we need to produce more food in the face of a changing climate.  And saline soils are one of the major limitations of crop productivity.  Perhaps a third of the world's food is grown using irrigated conditions.  And we all know, water is becoming a scarce of resource and the quality of the water is going down.  And it's a problem already and perhaps more importantly, it's going to be an increasing problem.  It's estimated that a fifth of the world's irrigated lands is significantly affected by salinity and it's getting worst.

Chris -   Is this because when we consistently put water out of rivers and things on land and that water may contain a small amount of salt, as that gets consumed by the plants or by evaporation, the salt is left behind so the soil over time, progressively deteriorates?

Mark -   Yes, that's exactly right, Chris.  And also, if you put water on, you tend to put too much water on and it's seeps back down into the water way from which you pumped the water, and it's going through soil which often has a small number of salt.  So you also get a re-circulation of salts building up and building up over time.

Chris -   And what does that do to the plants?  Why won't they grow on salty soil?

Mark -   Yeah, there's a few reasons.  But the main one is that the plants try to keep the salt out.  In fact, plants are pretty good at keeping most of the salt out.  But because there's so much there, beating at the door of the plant's roots, the plants struggle to keep it all out and over time, the salt accumulates up in the shoot, and leads to premature aging of the leaves.  And so, the plant which has thrown all that energy into growing all those leaves, loses them. They die before the plants got its money's worth out of those leaves.  And so, you get the plant being ground down because of this premature death of its leaves, just due to the simple build-up of the salt.

Chris -   So presumably, I mean, one way to tackle this is to, first of all, start to look for plants that do grow quite well on salty or salt-contaminated soils and then ask how they deal with it.

Mark -   Yes.  There's a couple of ways.  You've just described what we would call a forward genetic approach, a genetic approach where we look for natural variation and then understand the molecular basis.  You know, what molecules, what genes are different in the plants which have got those differences in terms of salinity and we certainly do that.  The other approach is to try to understand the processes, the mechanisms that plants are employing, to try to keep the salt out of the shoots and then see if you can manipulate those processes, using genetic modification.

Chris -   And is that what you've done?

Mark -   Yes.  The reality is you actually do bit of both and to combine the two techniques.  And they meet in the middle, which is actually the way we did it.  There are genes that encode proteins that transport sodium and one of these genes allows the sodium to move into cells.  And what it was these doing, it is actually doing it in the cells that were immediately around the pipes.  They're called xylem vessels that move the water from the roots to the shoots.  So, the plant tries to keep the sodium out but then some sodium eventually reaches these pipes that are in the centre of the roots, taking the water to the shoot.  And it's like a last ditch rescue process by the plants where they say, "Look, that sodium is in those pipes.  We can't let it get to the shoot or we're in real trouble."  And so, it let's the sodium back into the cells that are immediately surrounding the pipes.  And, that slows cells and in some cases, it stops the sodium actually reaching the shoots.  And what we did was develop techniques which allowed us to increase the levels of expression of that gene, immediately around those cells that are buried right in the heart of the root to increase this retrieval of sodium out of the water on its way up to the shoot, and that has made the plants so tolerant.

Chris -   So how did you do that rather clever trick of making that gene only get turned on in those cells around these xylem vessels because that's the breakthrough step, isn't it really?

Mark -   Yes, it is.  There's different ways you can do this.  One is to try to discover little bits of DNA which will activate genes in specific parts of the plant.  So that's one way you can do it a very direct way.  In the meantime, we're using a model plant.  It's called Arabidopsis.  It's a silly little weed, but you can do lots of really nice molecular genetics with it.  And what we did was throw into the genome of this little plant, this little weed, a little bit of DNA which allows us to turn on genes.  But we threw it on in random in the genome, made thousands of these plants and then looked at the plants to find ones which had the right pattern of expression.  So the initial generation of the plants was random and then we looked to find plants which had by fluke, this bit of DNA landing in a part of the genome that would activate that gene only in the inner half of the root.

Chris -   Big question though, Mark must be a course, it's one thing to do this in thale cress, the plant sciences fruit fly.  But we don't eat that.  So what about things that we do eat?  Could you put this same genetic combination into rice, into barley, wheat, and so on?  The kinds of things we do rely on for food staples.

Mark -   Absolutely, Chris.  We have done this in rice and the results are looking very promising.  We look like we've worked out how to reduce the sodium concentration.  Well we have reduced the sodium concentration in the shoots of rice and we're in the process of testing the effect of that on yield.  The first experiments did improve yield, but we just want to again be fairly conservative rather than just shooting off the results rapidly.  But it's looking very promising.  To turn the genes on in wheat and barley, maze, it's actually quite difficult because these molecular genetic tricks that we're able to use on Arabidopsis, we just simply can't do it.  We're technically not able to do it in wheat and barley.  So what we're doing now is we're having a program to discover the promoters that would help us turn this on, so going back to a very direct but slower way of manipulating an expression in wheat and barley.  We actually have transgenic plants in the glasshouse at the moment for wheat and barley and we're limited by bulking up the seed, and we're just at that stage at the moment.  So keep your fingers crossed for us and hopefully in the year's time, we'll be able to say if we've done it in the other crops as well.

Chris -   What about safety though, because we're already worried about rice because of things like arsenic?  Could fiddling around with the way the plant handles certain salts like this have implications for the accumulation in the plant of other things that are not good for us, as well as giving us food, we'll end up eating something we shouldn't?

Mark -   Yes, that's a good question and fortunately, we have analytical technologies here in Adelaide to measure a large number of different elements and we have checked that.  And it's quite extraordinary. This transporter is very specific for transporting sodium.  And it's only one other element that we've measured has an altered - has differences in it's accumulation- that's potassium, which is really not going to affect the nutrition of the plants very much at all.  We generally only eat the grain and the grains don't get affected at all, even their sodium.

A molecular model of a fragment of DNA

08:33 - Discovering New Viruses

Jan Arthur discusses how her team find new viruses by analysing faecal samples...

Discovering New Viruses
with Jane Arthur, Institute of Medical and Veterinary Sciences, Adelaide

Jane -   Hi.  I'm Jane Arthur and I work at the Institute of Medical and Veterinary Science in Adelaide.  And I do studies on what causes gastroenteritis in kids.  And so, the kids that are coming to hospital that the parents are sick of vomiting and pooping all over the house and they bring them to the hospital and say, "What's wrong with my child?"  And for many years, there's been a huge gap in our diagnostics.  So there are some bacteria that we know about.  There's rotavirus that we all know about.  But when you actually look at the studies, about 60% of kids that are turning up at a hospital aren't getting diagnosed.  And so, we decided what we would do is try and work out ways of getting more sensitive diagnostics and look for more viruses that were probably out there causing gastro.Layers in an oyster shell

Chris -   So in addition to bacteria, lots of people have heard of say, E. coli or salmonella as bacterial causes of food poisoning, viruses are big players too then?

Jane -   Yes, they are and particularly the norovirus.  That's the big one that' been around particularly in the last few years.  There's been lots and lots of outbreaks with norovirus and it can come through food poisoning, contamination as the people are cooking it or the classic is through oysters that have been from areas where there's faeces going into the sea and they just filter it out, and hang on to it until you eat it.

Chris -   And what you're saying is that that accounts for a proportion of the ones we know about, but there are a lot of unknowns in there.  You found two new ones.  How?

DNA fragmentJane -   Poo is basically DNA soup.  So we filtered down to the level where we'd actually just get viruses.  Then we concentrated them down by spinning them really hard.  And then in that, we then popped open the virus shells and pulled out the nucleic acid and amplified that up.  And then tried to work out what they were.

Chris -   It's probably about 30 or 40 years since someone last discovered a new virus that causes gastroenteritis.  Why has it taken so long?

Jane -   It's really hard.  I mean, if you don't know what you're looking for, to be able to pull out the genetic information from a soup of DNA and RNA that comes from plants and animals, and the gut bacteria, it's very difficult.  So it's taken this amount of time for the molecular techniques in the lab to be able to get to the point where it's actually possible.

Chris -   What proportion of the cases is the two new ones you've discovered?

Jane -   Well the two new ones we've discovered, the most important one is the human bocavirus 2 and that's about 17%, maybe 10 to 17% depending on the year.  The other one is human bocavirus 3 and that one we don't know.  That's about 3%, but it's also present a lot of the time in children that don't have gastro.  So, we haven't actually formed a link there.

Chris -   So what else is lurking out there then?

Jane -   Quite a lot because even when we found this virus and we went back and analysed our study, we founded it at 17% in one particular year.  But even then, it's still only accounting for about 10% of the 30% that was missing.  So there could be at least three or four, maybe even 10 other agents out there.

Chris -   And it's not just in Australia?

Jane -   No.  This is all over the world.  Other people have now found the human bocavirus in Pakistan and in the UK, and America.

Chris -   So now you know this, are we in a position to do anything about it?

Jane -   At the moment, no.  But we've been working on a way of making the coat from the virus and hopefully, we'll be able to - in the future, be able to use that as a vaccine.  There's a related virus in dogs that they use exactly that thing to protect the dogs against, so a canine-type of virus.

Chris -   So now you've got the genetic sequence, what you're saying is you can borrow bits of the surface of the virus to make it into a vaccine.

Jane -   Yes.  Well this virus is actually quite clever because the proteins, the molecules that make up the code, you don't actually need the rest of the virus there.  If you just take that out and put it in a system where you can get large amounts of it made, they spontaneously form up to these little hexagons and generate virus particles.  And so, you get the whole effect of the virus particle when you do the vaccination rather than just a little bit of it.

Chris -   And they're not harmful?

Jane -   No, not as far as we're aware.  No.  What's been going on in dogs has been perfectly acceptable.  So who knows?  Maybe we'll be able to have vaccine out against these.  I mean, the rotavirus vaccine has been wonderfully protective here in Australia.  So maybe we'll be able to knock this on the head too.

13:34 - Learning to make wine

We find out about one of the world's few degrees where drinking and making wine are the main things on the agenda...

Learning to make wine
with Cassandra Collins, University of Adelaide

Cassandra -   My name's Cassandra Collins and I'm a University of Adelaide lecturer in viticulture.

Chris -   Is this the only place in the world where I can come and do a course in how to make a fine bottle of wine?

Cassandra -   No, it's not the only place but it is one of the few.  There's a few other places in Australia.  There's Charles Sturt University and also smaller place like Curtin University, and University of Melbourne that do offer aspects of viticulture and/or wine making.

Chris -   It's still quite rare.  What an amazing thing to do though, to come to a university and drink, which is what most students aspire to do anyway and you can make it part of the course.

Cassandra -   That's true.  There's also many of the technical aspects, not just drinking.  But it is definitely one of the benefits of doing this type of course.  We cover all things right from how to grow grapes and best manage them, to produce high quality fruit that then can be made into high quality wines.  And for some students, they then also go on to learn more about marketing and the business side of the wine industry as well.  So we do cover all aspects of the industry which is quite exciting.Wine

Chris -   Who does that kind of course?

Cassandra -   It's a real mix of people.  You'll get undergraduate students that have maybe come from wine-making families themselves and want to learn more about the science behind it, and help them develop themselves in their future career in the wine industry.  And then you'll also get quite a few students that are a little bit older that have decided they want a career change and want to move into something like the wine industry.  And often, there's a bit of romance and there's definitely a lot of creative energy that goes into the wine industry.  And it does attract those sorts of people.  So we get a wonderful mix of personalities and people from such different backgrounds.  It makes it a pleasure in terms of teaching because you get to meet these people and then learn more about where they've come from.  So that's another benefit.

Chris -   Exam time must be fantastic.  Presumably, you sit down with what the students have made and you get to taste it.

Cassandra -   Yeah, that's true.  Not always as pleasurable as you might think.  At the end of the today, they're still learning.

Chris -   If they make a horrible wine, you make them drink it so they can learn to do it better next time.

Cassandra -   Well to be honest, I do get cases and cases of it.  So yeah, they are left drinking of it at some level.

Chris -   But the key thing is that, I mean, this is a serious business is, isn't it?  I mean, it's a big business.  So how many students are you turning out every year into this industry?

Cassandra -   Okay.  It depends on what they're majoring in but approximately, 50 to 100 depending on their specialty and it does vary a little bit with the trends in the industries in terms of popularity.  So yeah, it does depend on that, but on average, between 50 to 100.

Chris -   It's a three-year course.

Cassandra -   Oenology or wine making is currently a four-year degree.  Viticulture was a three-year degree, but as of next year, all students will be required to do four years.  And what we've done is to integrate more of the grape growing viticulture side of things with the wine making, so students end up with a much more rounded degree even though they can still major in one or the other, so...

Chris -   What about the fact that - because you mentioned some students come from wine-making families and that kind of thing- are you surprised by that, that a lot of these families don't think that they just know everything and they still have something to learn or that they want to even embrace science and bring that into the art of wine making, and it becomes a science rather than an art?

Cassandra -   I think it's, you know, it's also an opportunity for them to learn more firsthand in terms of the latest technologies, also how to present and communicate information which is only going to be valuable to them once they return back in to the wine industry.  So I guess there's lots of side benefits.  It's also an exercise in networking essentially as well because you've got this group of people that are all focused and passionate about the one industry, studying side by side.  I mean, it's an opportunity for them to spur each other on and meet each other as well.  So it's another advantage and I think another reason why wine making families would end up in this system as well.

Chris -   Do you get invited to a lot of parties as a result?  And presumably, you know everybody across the Barossa now.  You must - you must get invites to a lot of these places and be quite in demand.

Cassandra -   That's another wonderful thing about this industry, is the support from the growers, from the wine makers, from the big companies in terms of our research, in terms of allowing our students to come and visit them, to give them their real life, realistic perspective on what's happening in the industry, what's important to them.  We're really lucky that they embrace that and allow us to be a big part of their world as well.  So it's kind of like one big family in a way.

Chris -   And when I fly home later this week, what should I put in my 40 kilos of luggage allowance?  Throw away my clothes and take home 40 kilos of what?

Cassandra -   Good question.  I think you should take a mix dozen actually, at least.  There's too many ones to choose from.  I had a beautiful example of Meshach from Grant Burge the other day. We were lucky enough to take the students out there and we had a wine tasting.  So I'd highly recommend having some of that.  In terms of white wine, I'm always big fan of an older Eileen Hardy Chardonnay.  And also, some of our smaller producers in the Adelaide Hills, I've got some fabulous Sauvignon Blancs and some Chardonnays that are worth checking out.  So I would definitely try and squeeze a few of those into the suitcase.

cotton plant roots

20:09 - Too Much Boron

Tim Sutton is grappling with the problem of too much Boron in Southern Australia...

Too Much Boron
with Tim Sutton, University of Adelaide

Tim -   Boron is a naturally-carrying salt soil element that is naturally quite high in concentration in soils of marine origin and that covers most of Southern Australia.  So in South Australia, for example, in our grain growing regions, we think about 30% of our soils have levels of boron above about 15 mg/kg in the top 100 cm soil, just generally consider the threshold for boron toxicity.

Chris -   So when you grow a plant in a soil like that, what impact does it have on the plant itself?  Is it directly toxic in some way?

Tim - It is.  The boron in the soil is virtually immediately taken up by the plant roots.  Itcotton plant roots gets into the transpiration stream.  It then accumulates in the leaves.  Once it gets to a certain threshold concentration in the leaves, it affects metabolic processes.  The plant cells die.  The leaves eventually die off and you get a plant that's really struggling to survive with that amount of boron in its leaves.  And the history of this is quite interesting.  Boron toxicity was really only discovered as a problem in Southern Australia in the early 1980s.  There was an association made between boron content in leaves and boron content in soil samples taken across sites in Southern Australia.  And so, this started the whole process of traditional plant breeding at the Waite Campus whereby, one of the first tips was the screening for wild relatives of barley.  They were naturally highly tolerant to boron toxicity.  And one of the most tolerant lines that was discovered in their early work was a line called Sahara.  It's an Algerian land race.  It comes from obviously West Africa and it's highly boron tolerant.  It grows very heavily on concentrations of boron in the soil that far exceed anything we see in an agronomic situation.  You wouldn't grow them as a farmer because you wouldn't get a good crop out of them.

Chris -   And so your plan would be of course, to identify strains like that and then cross those with high yielding varieties so you get the best of both worlds.  You get the yield plus you get the ability to grow well on a soil that's got a lot of boron in it.

Tim -   That's correct and that is the fundamental of modern plant breeding.  So the line Sahara has been used extensively in breeding programs across southern Australia as a donor linefor the tolerants to boron trait and that has been integrated into more agronomic lands of barley using traditional breeding approaches.

Chris -   How do you know that you've got the boron resistant trait into the progeny, into the new hybrid that you make by crossing the resistant form with the high yielding variety?

Tim -   We can look at the progeny from those crosses and we can phenotypically assess them.  Are they boron tolerant or are they not?  If they are, they obviously have the genes or genetic loci are required for tolerance or we can use more modern techniques, utilising molecular markers, or we can use a DNA tag, we know is linked to the boron tolerance trait of interest, and we can screen progeny, resulting from crosses for that molecular marker.

Chris -   So do you actually know then, what genes are responsible for making plants grow well even when there is an overdose of boron in the soil?  Have you got that gene that does that?

barleyTim -   Yes, we do.  We have. We know of at least four of the major genes in barley that was identified through traditional mapping work in the late 90s of this campus.  We've since cloned about three of those, three of the four major transporters.  So we're getting a good grip on the molecular bases for these tolerance traits in barley.

Chris -   So you say transporters.  So, these genes make some kind of pump that can move boron out  of the plant if it's in a soil, where boron is trying to come in to the plant, it can get rid of it.

Tim -   That's correct.  The main transporter located on chromosome four of barley is a membrane efflux transporter and its role in the plant is to pump boron out, once it gets into the cell.  And the net effect of that is, is there's less accumulation in the leaves of the plant.  The plants are happier.  They don't suffer from toxicity.

Chris -   What about if you put that same plant on a soil that's now not got too much boron?  Is it still happier?

Tim -   It depends which gene you're talking about.  The major one on chromosome four is constitutively expressed and what that means is that it's not induced by the presence of boron.  It's on all the time everywhere.  The downside of that is that under conditions of lower boron supply in the soil, these plants actually suffer from slight symptoms of boron deficiency.  They're not getting enough boron into their leaves to be happy.  And that's something that we're working on trying to modify.  That's a good example of why it's really important to clone these genes.  Identify the exact sequence of these genes.  And once we know that, we can look at the regulator elements upstream of these genes that control their expression.  In other words, when and how much are these things expressed.  Once we know these things, we can then start to modify them and one of the things we could try and do, and we are trying to do indeed is to make this boron transporter inducible to boron so that when it's not needed in the plant, it's not expressed.  But when it is needed under conditions of high boron, the gene comes on, and you get the tolerance phenotype that you're looking for.

Chris -   Which would be incredibly neat because the plant then just responds to the environment according to what it needs.  And you don't have to have more than one type of plant.  If you were to look at the impact of this technology presuming you're going to be successful, what difference could it make to the yield that you'll get, both here in Australia and perhaps to other countries around the world?

Tim -   The numbers that we think occur, at least in southern Australia, we think about 30% of our soils were affected by boron.  That could acquire to $250 million of annual production.  But talking more globally, it's difficult to say because often, these problems don't come in isolation.  Often when you have a boron toxic soil that comes along with things like salinity, aluminium toxicity, a whole range of problems that are difficult to isolate and single out.  That could have a big impact.

Chris -   And how close are you to having those crops ready to go?

Tim -   We're working very hard to get the material to a stage where it could be useful for farmers, and in fact, we're in the stage two or our second year now of a GM field trial in South Australia where we have gene material containing the boron tolerance gene from Sahara.  So we're evaluating that material at the present in this growing season.

Forest Fire

27:02 - Bushfires and Wine-making

Bushfires can ruin a wine when smoke chemicals penetrate the grapevine. But now Adelaide-based scientists may have come up with a way to rescue a smoke-damaged vintage...

Bushfires and Wine-making
with Kerry Wilkinson, University of Adelaide

Chris - We're back to wine now and something else is a big problem, bushfires.  But not for the reason you might think.  And thankfully, Kerry Wilkinson might have a solution.

Forest FireKerry -   When a bushfire occurs or prescribed burning occurs in close proximity to wine regions, there's the risk that that smoke might linger around and in some cases, can be taken up by grape vines where smoke exposure occurs for an extended period of time.  And what we see is that that smoke translates to a taint that can be detected in the wine in some cases.

Chris -   Well, so what - there are chemicals, some kind of volatile agents in the smoke presumably that then adds or impregnates the surface of the grapes and this then gets carried over into the press?

Kerry -   Some of these processes are still under investigation.  We don't yet have all the answers, but it certainly seems to be that some of the components of smoke are being absorbed by grapevines and by fruit, and that these, they're carrying over into the wine and can influence the aroma and sensory properties of the finished product.

Chris -   Is the effect always negative? Is it always bad news for the wine if that happens?

Kerry -   We don't see an apparent taint in all wines where vineyard smoke exposure has occurred, but where it's prolonged, there is a risk that we some smoky burnt-meat type characters in a wine.  And in some wines, particularly a delicate Riesling for example, this can be detrimental to the quality.

Chris -   How much smoke do you actually need?  So a bonfire in the vineyard is probably trivial but a big bushfire is likely to be more dramatic.

Kerry -   That's true.  The research is ongoing.  So we haven't yet been able to say this is the minimum duration of exposure that's required to translate into a tainted wine.  Where we have seen significant issues with smoke taint, it's generally a case of a large fire that's ongoing for a number of days or even weeks, and where that smoke hangs around for a considerable length of time.

Chris -   And are all grape varieties equivalently susceptible to this or are some going to see their flavours impacted more than others?

Kerry -   That's actually the focus of a current research project.  We're actually looking at conducting a varietal of trial to see if there are any physiological characteristics of certain varieties that make them more or less susceptible.  So the idea is that some of the characteristics of certain grapevines, for example their leaf area or their bunch size might influence the levels of smoke that are being absorbed in the field.  And so hopefully, what we can do is identify varieties that are less susceptible to the uptake that might be more appropriate for growing in regions where, you know, they're prone to smoke.

Chris -   Is there anything you can do about it once it's actually happened because in Victoria, I think last year where there were some fires, they had to throw away huge amount of wine?

Kerry -   Yeah, the Australian wine industry, particularly in Victoria which has had a few incidences in recent years, they're really concerned with their brand.  And so, in many cases, wineries aren't prepared to risk their reputation by putting out a product that they don't believe is up to their standards of quality.  We've been conducting some research, looking at a technique that involves reverseosmosis and solid-phase absorption which might have the capacity.  It certainly looks promising to try to overcome the issues of smoke taint and remove that taint.Wineglasses

Chris -   So would you then take the product and try to extract just the molecules that are making that smoky taste or do you go to the grapes and do something to them?

Kerry -   At this stage the amelioration techniques are being applied to wine and that's because some research has recently identified that some of these smoke compounds are being conjugated by the grapevines so they're present in more complicated forms than what we're able to detect.  And what we've shown is that during wine making, these more complicated molecules are being broken down to release the compounds contributing smoke, smoky-type aromas.  So, it's better for us to be treating the wine as a finished product to try to remove the offensive compounds rather than treating the grapes where, all the grape juice, where we're actually not able to target those molecules more specifically.

Chris -   There must be hundreds, if not, thousands of different flavourants in an individual wine.  So how do you know what's smoke and how do you know what's actually good, honest grape flavour?

Kerry -   That's true.  And even some of the compounds that are present in smoke are natural components of grapes as well.  So that's part of the complication of determining a method that we can use for trying to remove smoke taint is coming up with techniques that, I guess, act more specifically on the offensive molecules and try not to have so much of an impact on the desirable compounds.

Chris -   So how do you actually do that?  Are you growing grapes and then wafting smoke over them so you can then see how much they take up or something?

Kerry -   We actually are.  We're conducting a number of fume trials where we build  purpose-built smoke tents around our grape vines and we then generate smoke and put smoke inside these tents for a specified period of time, and we come back and collect grapes at different times afterwards or harvest the grapes, once they're mature to make wine out of them to conduct a number of chemical and sensory analyses at a later date.

Chris -   And have you got some candidate compounds that you know translate into these nasty aromas that you think you can now remove?

Kerry -   There are two marker compounds that are currently being used, guaiacol and 4-methylguaiacol.  And these are reasonably liable indicators when their levels are higher in smoke-affected grapes and smoke-affected wines it tends to correlate with higher levels of perceived smoky characters.  The complication is that these compounds are also derived from barrel maturations.  So when a wine is matured in a barrel, you'll see these compounds as well.  So we know that they're not solely responsible.  And an ongoing research is trying to identify some of the other compounds that are responsible.

Chris -   And the removal process, how effective actually is that and does it leave the wine fairly otherwise untainted then?

Kerry -   The project that we ran last year, we took a smoke tainted pinot and it had quite an apparent smoky character and we we're able to reduce the levels guaiacol from 12 micrograms/ litre, down to 5 micrograms/litre.  And perhaps, most importantly, was the sensory results we got from this.  And our panel could readily distinguish between the wine before and after treatment, but not only that, there was an improved acceptability of the wine after treatment.  So it had less intense smoky-type characters and more intense fruit characters.  There is the potential that we're also removing desirable flavour compounds.  You know, we don't deny that.  But it does seem to be a process that at least gives wine makers some hope where they, you know, don't have too many options available to them.

43:10 - Polysaccharides - The Key to a Healthy Intestine.

We discover the health benefits of cereals rich in polysaccharides...

Polysaccharides - The Key to a Healthy Intestine.
with Geoff Fincher, University of Adelaide

Chris - To human health now and the study of plant polysaccharides.  These are the giant molecules that plants make by linking sugars together to form their cell walls.  It turns out that these polysaccharides make a major contribution to keeping our intestines in tip-top shape.  Geoff Fincher.

Geoff -   We work on cereals and there's a potential to improve the value of cereals for human health.  And if we can understand how these polysaccharides are synthesized, then we can look for natural variation in the levels of their synthesis, so that we can hand on some of benefits of natural variation to human health or we can manipulate them.

Chris -   You say they're good for human health but in what way?  How are they affecting our health?

Geoff -   All right.  So as I've mentioned, cell walls over the years have been not terribly popular.  You know, student's eyes glaze over when you start talking about the structure of these polysaccharides.  But just in recent years, it's been discovered that they really have a major beneficial effect on human health in all sorts of different areas.  So, these polysaccharides have very long molecules, lots of sugar residues joined together.  They usually have an asymmetric confirmation which means they're much longer than they are wide and that means they form solutions of high viscosity.  They're thick in solution.  So you feed them to a human and there's no enzymes to digest them in the small intestine, and they increase the viscosity of the contents of the small intestine.  This slows down the rate of diffusion of enzymes and breakdown products of things that we can digest like starch and protein, and it means that there's awheat much slower release of say, glucose from glucose-containing polymers, a slower release generally of food.  And so, this has a lot of beneficial effects in terms of reducing glycemic index and this is of benefit to people with type 2 diabetes.  When they get down into the large intestine, down there, they're fermented to various short-chained fatty acids.  And some of these are believed to have anti-cancer effects and so, they reduce the risk of colorectal cancer.  And beyond that, there's a health claim which is allowed in the U.S. that these polysaccharides reduce serum cholesterol levels.  So if we reduce the risk of diabetes, cardiovascular disease and colorectal cancers, these things have got to be good.

Chris -   This only sounds like it, given that you've listed the things that probably kill more people than anything else.  What about the fact that we're now beginning to get very interested in the bacteria that live in our intestines as well and we know that they play a huge role in health and disease.  Do these things also impact on the bacteria as well?

Geoff -   So we, at the moment, have a project with CSIRO or Food Futures Flagship.  And this is one of the objectives, the major objectives of this project.  We have people within CSIRO who have microarray analysis where they can quantitate the level of different bacteria in our large intestine, and they can broadly classify them into good bacteria and bad bacteria in terms of human health.  And so, what we can do now is we can take these polysaccharides with different structures and we can do this either in vitro or in pigs, and we can see what effects these polysaccharides have on the dynamics of these bacterial populations.  And in our first pig trial that we finished last year, we added, we supplemented the diet with one of these cell wall polysaccharides.  We got a dramatic reduction in DNA damage in colonocytes which have lined the colon and we got a dramatic shift to beneficial bacteria in the large intestine.

Chris -   Which is very encouraging.  Are there any plants that make more of the right sort of these things?  Is that what you're trying to find, so they can then advice people what the best plants are or what would constitute the best diet?

Geoff -   Yeah.  I think that there are polysaccharides in all plants with the same sort of physico-chemical properties.  You know, they form this highly viscous solution and they have the potential to do these sort of things that I've mentioned.  But I guess the focus has been on the polysaccharides in cereals because they are the main source of food for most human societies.  And so, we're focusing on those and we certainly believe, and we can see for example, if you have different fine structures of these polysaccharides, you get different solubilities.  And the more soluble they are and the more soluble dietary fibre you have, apparently, the greater are the benefits.  So certainly, we are looking at the effect of fine structure on the physico-chemical properties and then on human health benefits.

Chris -   Do you think then in the future, if you can identify what the molecules are that are best for us, that you'll be able to put them in a pill?  Because there are some people, I think there was a stat published in the U.K. the other day, more than a million people do not eat any fruit or vegetables ever.  And I'm sure it's the same here in Australia.

Geoff -   It is the same.  It'd be a mighty big pill.  I'd have to say that because you really do need, you know, in terms of volume, you need quite a lot of this material.  But this is - but it's a good point because we have to come up with something which is beneficial to human health, which humans don't have to leave a kilogram of a day.  You know, it has to be concentrated enough in a serve of a food which is reasonable to expect people to eat.

oatsChris -   So can I ask you to suggest what I should have in my five-a-day on my plate, in order to get the best bang for my buck in my, not just my colon, but my intestine in total?

Geoff -   Well, I think that these polysaccharides in cereal grains, probably the best ones that are naturally occurring are in oats and barley.  Now oats, you can have so, eat up your porridge and you'll do really well in terms of bowel health.  Barley is also are rich source, but it's not quite as attractive as a human food and what we're trying to do is increase the solubility and the amount of these polysaccharides in wheat so that people can get them through wheat, and eventually rice as well.

Grapes from the Guadalupe Valle, Baja California, Mexico, during the pigmentation stage.

49:54 - When is a grape ready for wine making?

We discover how the timing of a grape killing itself, is the secret to a producing a good wine...

When is a grape ready for wine making?
with Steve Tyerman, University of Adelaide

Chris - Now here's a question.  What makes a grape ideal for turning into wine?  Steve Tyerman.

Steve -   Well what we've discovered in the berries of grapevines is that, later in development, as they're ripening, they undergo a process of cell death.  Now, this hasn'tGrapes from the Guadalupe Valle, Baja California, Mexico, during the pigmentation stage. been recognised previously and it occurs fairly late in ripening, but still before harvest.  Now, we see this through using dyes that detect living and dead cells.  And what was quite extraordinary was the fact that we see big differences between different varieties.  So in wine grapes, we see this progressive cell death which gets worse and worse until harvest.  So only a small proportion of the actual berry is still living. Whereas in table grape varieties, we don't see that happen at all.  In fact, you can go to the supermarket and buy some grapes, the actual berries and do the tests on these and generally, you'll see that they're all still living.  So they're nice and crisp and turgid in the mouth, and they taste nice and fresh, whereas a grape berry if you do that, they feel like just a bag of sugar, sugary fluid.  And there's no turgidity or crispness about them.  It's very likely that they're selected for that very reason.

Chris -   Looking at the picture you've got here of precisely this effect, can you just talk me through what that picture is actually showing?

Steve -   Okay.  Well what we've got on the screen is a transverse section for berry, stained with a dye that detects living cells and the table grape variety, which is Thompson seedless, shows that most of the cells were living through the berry, whereas the wine grape variety that you're looking at as Chardonnay, it's a popular one variety across the world, and a popular Bordeaux style as well.  And you can see that there are just a few cells living around the periphery of the berry and this is associated with the vasculature, but the large juice cells, which make up most of the volume of the berry are actually dead or dying.  So their membranes have disintegrated and released the contents of the various compartments in the cell that is mixed and it's very likely that this has actually influenced the biochemistry as well as the general structure, and shape of the berry.

Chris -   So, presumably, an experienced wine maker will basically be doing with their tongue what you're clever dye is doing here on the screen?

Steve -   Yeah.

Chris -   They're be able to tell when a grape has reached that appropriate level of cell death for the flavours to be coming out.  So that's an ideal time to make wine?

Steve -   Yes, that's probably correct.  We're testing that at the moment using berry sensory analysis to see if it correlates with the onset of cell death.  But wine makers often describe this engusment of flavour where there's a sudden increase in the varietal flavours that one detects with say, reisling, viognier.  And this engusment of flavours sometimes occurs very rapidly.  So it could well be associated with the onset of cell death, but we haven't actually proven that yet.  We've just shown that this cell death stage occurs late in ripening and before harvest.  So it certainly is happening and it is possible that the wine makers and viticulturists are detecting it.  But we don't know that for sure yet.

Chris -   Could you make that happen at different stages of ripening in a grape, in order to make it juicable, if you like, and therefore, alter subtly the characteristic of the wine you could make?

shiraz grapesSteve -   Yeah.  But we're interested in it for that reason, but also, there's a correlation between the onset of cell death in the berry and water loss from the berry.  So in a warm climate such as we have in Australia, you get a lot of - you can get a lot of water evaporating from a berry-  and it's correlated with the onset of this cell death.  So the more cell death that occurs in the berry, the more weight loss occurs.  And we see this generally across all the wine grape varieties and those that have more cell death tend to be more susceptible to weight loss.  In fact, this can be so much so that in the variety Shiraz, they can lose up to 30% of the maximum weight of the berry before harvest, which to the growers is a lot of yield loss.  It's not necessarily a bad thing for the wine makers because you get more sugar, if water evaporates from the berry that concentrates the sugar.  But we need to understand why that happens in some varieties more than a dozen others because, you know, in a warm or dry climate, it's likely that this will be exacerbated.  So, we're interested in them from a climate point of view.  But as you say, if we can make this happen earlier or even not allow it to happen, we don't know what would happen if that occurred to a lesser extent in terms of flavour development or to a greater extent, or if it occurred earlier, whether that would turn to be useful or not, I don't know.

Chris -   But maybe if you could trigger that by spraying the plant with something so then all the plants, all the grapes in register, all kill themselves internally.  So then you minimise the water loss, maximise the flavour, and you know exactly when you want to pick them.

Steve -   Well, one of the issues that we have actually is that sugar concentrations in berries has been increasing over the decades and one can claim that this is an impact of climate change.  So for example, red grape varieties in Australia have increased when we make wine from them.  The alcohol content is increased by about 1% per decade, which you know, has health implications and also flavour implications because it's harder to balance a hot alcoholic wine with other flavours.  So, we're actually interested in Australia in reducing the alcohol content.  And to reduce the alcohol content, we have to reduce the sugar content in the berry.  So this onset of cell death and water loss has a direct impact on the sugar because if water is lost from the berry, the sugar concentration increases.  If we can get this process to occur earlier in sugar ripeness, that should result in less water loss at harvest and potentially lower sugar concentrations in the berry.

56:25 - Why are wines served at different temperatures?

Why do we serve white wine when chilled and red wine at room temperature?

Why are wines served at different temperatures?

We posed this question to Marjorie King, Sensory Research Technician with Agriculture Canada...First of all, red and white wines have different chemical compositions that influence their sensory perception and their sensory traits. The aromatic white wines and these are things like Chenin Blanc, Gewurztraminer, some of the Rieslings, you serve them the coolest so it would be about 8Ã?,°C. They have a relatively higher proportion of aldehydes and esters and terpenes that fill up the head space of the glass and at the lower temperature. So they will project their fruitiness which is a big part of the appreciation of those wines at a much lower temperature. The cooler temperature accentuates a bit of the acid and so, it creates a crispier, fresher kind of impression of the wine. If you do a Chardonnay-type wine or a wine in that style that is oaked, it can be served at a slightly higher temperature, so maybe 10Ã?,°C, maybe 11Ã?,°C. And the red wines, we have the phenolic compounds in the red wines, but with the polyphenols and the tannins, contribute to the structure in the mouth feel and that's very much linked to the appreciation in a good quality of red wine. These components are better tasted at a slightly higher temperature. So if you chill the red wine, it's not just that the flavour components don't come out into the head space as well, but the tannins and the polyphenols feel much more astringent and harsher in the mouth and the acid is accentuated as well. If you serve a red wine that's really warm, what you get then is the alcohol starts to dominate the head space in the glass and you get the perception of an alcoholic wine, and you don't appreciate all the fruity components that are in the wine. So if we serve those at about 19Ã?,°C, you get a much more pleasant overall balanced wine.


Add a comment