Impact of Chromatin Transfer and Spindle Abnormalities on Pollen Fertility and Pollen Size in Plantago lanceolata L.

The phenomenon of cytomixis involving chromatin transfer and spindle abnormalities were recorded for the first time in the diploid (n=6) accession of Plantago lanceolata scored from Parvati Valley, Kullu District, Himachal Pradesh (India). Cytomixis with chromatin transfer involved 2-3 PMCs (pollen mother cells) at different stages of meiosis from early prophase-I to T-II, but the maximum frequency of PMCs involved in cytomixis was recorded during the early prophase stages of meiosis-I (11.03%). The transfer of chromatin material among meiocytes was observed to be both partial and complete resulting into PMCs with hypo- and hyperploid chromosome numbers (2n=14, 15). During cytomixis, nucleolus also transmigrated to neighbouring PMCs and the PMCs with supernumerary nucleoli also resulted. Other meiotic abnormalities associated with cytomixis included chromatin stickiness, out of plate bivalents, laggards, bridges, unoriented chromosomes during A-I/T-I and A-II/T-II, and micronuclei. The effect of chromatin transfer, spindle abnormalities and associated meiotic anomalies on meiotic behaviour, pollen fertility and pollen size has been discussed. The cytomixis in P lanceolata seems to be a natural phenomenon under genetic control and certainly have played a role in the origin of aneuploids and polyploids.