[Nicci (OP)]

I planted flower bed full of white iceberg roses for the two years ago. Last year I found a new cultivar, dark pink iceberg roses and planted two of these pink rose bushes in the same flowerbed as the white ones. Recently the white roses began developing pink freckles. Now some of my white plants have changed completely pink. Is this common? And how does it happen?

[Don_1]

Your Iceberg roses can become flushed with pink due to changing soil conditions. Has there been a change in your soil's acidity? you could try using an ericacious fertiliser, or just a normal rose feed if no great change in your soil.

This species is also liable to become flushed with pink if it has been subject to a cool spring or autumn (more so spring).

Your pink or burgundy cultivars will not be affecting your white plants. I'm afraid you do not have a new cultivar and these are not uncommon problems with the white cultivar.

[lyner]

I am sure that "mutation" is not the correct term for what you saw.

[Nicci (OP)]

Not being much of an expert, it looked like a mutation (obviously inaccurate). The fertilizer point makes sense though and a dramatic drop in temperature, from 35 degrees C for most of the summer to the low 20's in the past could of days.

[lyner]

For an organism to show mutation effects all over, the damage to the DNA must have taken place in a sex cell which then became a whole new plant or animal. You can't get all the cells in an established organism to mutate in the same way and produce something as uniform as you saw in your roses.
This is the same argument which trounced Lamarque's idea about evolution.

[chris]

Is this due to transposons? I seem to remember reading that some plants contain unstable jumping genetic elements called transposons that leap around in the genome. Occasionally these leap into other genes and inactivate them or alter their behaviour.

Jamil Bacha wrote an article about transposons for us a short while back:

http://www.thenakedscientists.com/HTML/articles/article/jamilcolumn1.htm/

Chris

[Don_1]

I rather doubt this Chris in this instance, the soil and weather conditions I highlighted in my above post are well known for the effects seen by Nicci. It is not at all uncommon in this rose.