Asynapsis in cassava

A completely male sterile clone was identified in the germplasm and detailed meiosis showed it to be asynaptic. At pachytene all the chromosomes remained as univalents without any semblance to pairing. MI aslo showed 36 univalents in 97% of pollen mother cells. The bivalent like association in MI was as low as 0.03 per cell but the absence of pairing at pachytene and the lack of well defined x'mata suggested that they were only univalents lying closely together due to factors other than true pairing. The later stages were not well defined and univalents were noticed to divide. The scattering of chromosomes and irregular groupings resulted in polyads consequently all the pollen were sterile. The type of asynapsis noticed was ‘complete’. The presence of pollen sterility in all the plants of Ce-258 throughout the season ruled out environmental factors and suggested it was of genic nature.