Chromosome stickiness leading to desynapsis and sterility in safflower

概要

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In a population of safflower (Family: Asteraceae) treated with gamma rays three out of twenty five plants scored at 45KR treatment dose were found to have desynapsis and heavy chromosome stickiness spread at nearly all phases of division accompanied by high pollen sterility. Meiosis was perfectly normal in control plants however plants treated with gamma rays possessed different types of chromosomal aberrations. The variant plants scored were found to have medium type desynapsis as demonstrated by enhanced frequency of univalents per cell as opposed to bivalents in all the PMCs analyzed, a convincing indication of failure of synapsis between homologous pairs of chromosomes. The presence of other irregularities like disturbed sticky metaphase I/II, stickiness with secondary associations, stickiness with non-synchronous division and laggards at anaphase I were also encountered. Pollen sterility was also found to be high in such induced desynaptic plants. Thus the present study is an attempt to understand the genetic behavior of sterility as well as its mechanism through cytogenetic analysis of these sterile-desynaptic variants as our knowledge on these aspects is still very limited especially in case of safflower.