We were interested in finding out if tassel maturity has any effect on excision behaviour of the transposable element system operating at R-mb:cc. In the maize tassel, the florets shed pollen over a period of a week. Anthesis proceeds in a systematic and predictable manner, with the two florets in a spikelet shedding pollen on two subsequent days.
In R-mb:cc lines, pollinations were made on different days of pollen shed (day 1 to day 7). The resultant ears were scored on the basis of 'striping scale' and the average ear scores computed. Comparisons of the average scores of ears pollinated on different days of tassel maturation showed no statistically significant changes in phenotypic expression. In an earlier study, Levy and coworkers (Dev. Genet. 10:520-531, 1989) studied the association between tassel maturation and somatic excision frequency of Mu and found that there were no overall changes in Mu activity in the tassel during the period of pollen shedding.
It appears, therefore, that the excision behaviour of a transposable element may not show significant differences in different sectors of the tassel.
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