Cytogenetic analysis of starting materials
The starting plant material was analyzed in order to
exclude any cytogenetic variation that could influence
further analysis. The levels of ploidy and endopolyploidy
in rosette leaves from 3 week old plants were estimated.
The flow cytometry measurements were conducted on 20
plants, and two samples from each plant were analyzed. All
plants were found to be diploids. The young rosette leaves
exhibited two cycles of endoreduplication and the maximum
DNA content was 16C (Fig. 1a), which is consistent
with the organ specific endopolyploidy pattern in A. thaliana
(Galbraith et al. 1991). The chromosome number