Effect of cytomixis on the pollen size in 'Seabuckthorn' (Hippophae rhamnoides L., Elaeagnaceae)

Abstract

Present study reveals the occurrence of inter PMC transfer of chromatin material in the PMCs of 'Seabuckthorn' (Hippophae rhamnoides L.). The migration of chromatin is observed from early prophase up to telophase-I. In majority of the cases 2-4 PMCs are involved in chromatin transfer, however in rare occasions migration of chromatin occurs in groups. The migration of chromatin is observed to be partial as well as complete, which resulted into the formation of anucleated, hypo and hyperploid PMCs. In rare cases, direct fusion between two PMCs at AI lead to the formation of a polyploid PMC with 36 chromosomes. As a consequence of cytomixis various other associated meiotic anomalies such as chromatin stickiness at MI and late disjunction of bivalents at AI, pycnotic chromatin, bridges and laggards at anaphases and telophases are resulted. Microsporogenesis is also abnormal resulting in the formation of dyads, triads, and polyads with micronuclei. The cytomixis though do not cause much pollen sterility but it surely results in the formation of heterogenous sized fertile pollen grains. The pollen grains are classified into small, medium and large sized with medium sized pollen grains being in high frequency. The role of such fertile, especially, small and large sized pollen grains, in the origin of plants with aneuploid and polyploid chromosome number, can not be ruled out. The present meiotic count of n=9 is the first record for the study area. © 2008 The Japan Mendel Society.