Science Interviews


Sun, 28th Oct 2007

Kitchen Science - Home Cloning & Bananas

Dr Tim Upson, Cambridge Botanic Gardens

Listen Now    Download as mp3 from the show Cloning, Chimeras and Stem Cells

Weíve only recently been able to clone animals, but weíve actually been cloning plants for millennia, thousands of years.  So for this weekís Kitchen Science, Ben found out about a clone you can clone at home!

Ben -   For Kitchen Science this week we decided that we would talk to you about how you can clone an organism in your own home.  Thatís right, you can actually clone something yourself at home and itís really easy.  Iím actually here at Cambridge University Botanic Gardens and Iím with Tim Upson.  Hi Tim!

Tim -   Hi there.

BananasBen - We are looking into cloning plants today, now the cloning weíve heard about so far involves expensive lab equipment and carefully removing DNA from one cell and putting it into another.  So is that how you do it with plants?

Tim -   No, well thankfully plants are much easier. You can snap off a bit, stick it in some soil and wonderfully it will produce some new roots and youíve actually cloned a plant.  Itís the process of taking cuttings which millions of gardeners will do every year.

Ben -   So what is it that makes that new plant a clone?

Tim -   Itís because itís genetically identical to the parent. So in contrast if you were to sow some seeds, which have come about through sexual reproduction, of course thatís mixing of the genetic material and you get variation.

Ben -   So literally all you have to do to clone a plant at home is to cut a piece of one plant and plant it in the soil.

Tim -   Yes, plants have this wonderful property; their cells can re-differentiate into different materials.  So essentially if you take a shoot from a plant it will have leaves and it will have a stem.  Usually just underneath the surface of that stem some of those cells, in response to wounding and being cut will actually differentiate into roots.  These are called adventitious roots, new roots, and hey presto youíve got a plant with all its functioning parts the leaves, the stem and of course, the roots.

Ben -   So itís the ability to differentiate into different cell types that means a plant can do this, but do you know why I wouldnít be able to cut off the tip of my finger and plant it in some agar and grow a whole extra hand?

Tim -   Yes, in animals they donít have this ability to differentiate cells once theyíve become a certain part of the body.  Unless, I guess, you go all the way back to stem cells which have a similar kind of ability to plants.

Ben -   So could you consider plant cells to be very similar to stem cells in that regard?

Tim -   Yeah, I think thatís a good analogy actually.

Ben -   So how do we know that plant cells are capable of turning into all the different cell types?

Tim -   We now know that all of these are controlled by what are sometimes called plant hormones or plant growth compounds.  A good example is a hormone called Auxin, which encourages rooting.  When you go to the garden centre you can buy whatís called a plant rooting compound, and thatís high in auxins so when you dip the end of your shoot, which youíve just broken off, into that powder it gives it a burst of auxin and that encourages the roots to develop.

Ben -   This sounds like a really good way for us to get more, and different, plants into our gardens.  Are there any problems associated with having plant clones?

Tim -   Well there are.  One good reason for cloning is because you find a plant which has very good characteristics; maybe it has a particularly delicious fruit or wonderful flower.  But of course along with that can equally go some negative characteristics.  That can be particularly problematic for example when we talk about susceptibility to pest and diseases.  If you do then get an outbreak of it and youíve got a mass of clonal plants on an agricultural scale that could spell disaster if youíre a farmer.

Ben -   So a farmer would clone a particular plant because, for example, itís the best banana and the easiest to sell, so for commercial reasons cloning would make sense because youíll get more of the best type of fruit.

Tim -   Thatís exactly right and bananas are a very good example.  Bananas are cloned on a commercial scale, if you go to the tropics and look at the commercial banana plantations theyíre usually made up of clonal lines of selected cultivars.  Bananas are synonymous with something called panama disease which is a fungal disease which actually attacks the water conducting vessels.  Some of the favoured banana clones like Gros Michel and now Cavendish bananas which are grown widely throughout the world for commercial purposes have become vulnerable to this fungus.  As soon as it starts to attack a field, or essentially move from country to country it can devastate that banana industry, so it can cause big problems and we are talking potentially multi-million pound loss of crops here.

Ben -   So how can we avoid this happening?

Tim -   Well, it all comes back to encouraging genetic diversity and all we have to do is to look to people like subsistence farmers, they wouldnít just grow one clone they would grow a number, so if one proved potentially vulnerable to pest and disease theyíve got others that they can look to.  Commercially, of course, now theyíre looking to breed more diversity into bananas and of course breeding in resistance particularly to panama disease is obviously very important and a major goal.

Ben -   So while cloning can offer us more and better fruit, itís always best to remember that it would only take a small outbreak of disease to take bananas off the shelves.  Thatís all for Kitchen Science today, weíll be back next week.


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