Re: Hyb: Ploidy speculation

Linda,

You mentioned a simple tool to analyse the DNA.

I use flow cytometry to analyse the DNA content of Irisses. In the breesing
program I am working I convert diploid Irisses in vitro to tetraploid. In a
very early stage we take a small part of tissue and isolate nuclei and stain
them with a DNA dye, and analyse by flowcytometry the ploidy level. I
multiply the tetraploids and analyse this material again. In this way we can
exclude the mixoploid clones after two multiplication cycles.
In Iris I have seen a very strong selection in tissue culture for the
diploid tissue, if some diploid tissue is remaining it will become dominant
after some cycles of multiplication. I think this can be a reason why it is
in Iris difficult to produce tetraploids. In other crops that I am
converting like Lilium, Hosta, Hippeastrum and Tulipa this is a much smaller
problem.
In most crops I prefer to work with colchicine since this tends to give more
reproducable results in our lab compared to Oryzaline.

 
I 'am working in breeding of Dutch Iris. The most important cultivars are
crosses between I. xiphium and I. tingitana. The hybrids are sterile but
after converting them to tetraploid fertility is restored. I converted both
parent species and hybrids. During analyses we found that the DNA  content
of the diploid parents is different. The hybrid has intermediate DNA
content. If I receive unknown material I can tell on the basis of DNA
content what is the constitution of the material: A triploid with 2 sets of
tingitana has a different DNA content as an triploid with 1 set of
tingitana. I use the system also to detect in an early stage if a plant is a
hybrid after embryo culture.

It would be interesting to see if this system can also be used for other
Iris groups. 

The costs of the analyses of ploidy level that our laboratory charges per
sample is approx between 2 and 4 US$ plus costs per order. The costs of
converting Iris in our laboratory are approx. 600 US$ per cultivar but this
is based on a protocol for Dutch Iris. We work mainly for the professional
Dutch plant breeders but we also do some work for amateur breeders.

Best regards,


Eloy Boon

Iribov
The Netherlands










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