Temperature influenced variation in the chromosomal behaviour of male and female sex cells in Sunn hemp (Crotalaria juncea Linn., Fabaceae)

摘要

Influence of varying temperatures i.e. 31 degreesC, 44.4 degreesC, and 36 degreesC on the behaviour of chromosomes was studied in the pollen mother cells (pmcs) and embryo-sac mother cells (emcs) of Crotalaria juncea L. While meiosis in both the sex cells at 31 degreesC was normal with perfect bivalent formation observed in cells at diplotene/diakinesis and metaphase-I stages, abnormal meiosis, characterized by the failure of synapsed chromosomes to retain chiasmata at diakinesis and later stages resulting in the formation of varying frequencies of univalents, was a common feature at 44.4 degreesC. Interestingly, the felling apart of homologues was found to be specific to microsporogenesis and megasporogenesis showed normal synapsis. However, with a subsequent fall in temperature to 36 degreesC, all the pmcs restored their normal pairing behaviour. The possible causes of such differential behaviour of chromosomes in the two sex cells and its significance is discussed. [References: 46]