Structural heterozygosity and cytomixis driven pollen sterility in<i>Anemone rivularis</i>Buch.-Ham. ex DC. from Western Himalaya (India)

Abstract

Meiotic studies have been carried out on 12 accessions of Anemone rivularis from different regions of Western Himalaya. The accessions from Chamba, Kullu and Kinnaur districts of Himachal Pradesh and Uttarkashi district of Uttarakhand showed a normal meiotic course leading to high pollen fertility (87–100%). However, the accession scored from Saat Tal, Uttarakhand showed structural heterozygosity for reciprocal translocations. This is the first report of occurrence of structural heterozygosity in the species. Out of the 604 analysed pollen mother cells (PMCs), 38.41% (232) showed quadrivalent formation at diakinesis and metaphase-I. Comparison of chiasma frequency was also performed among selected populations using one-way analysis of variance (ANOVA), which showed significant differences. The occurrence of cytomixis involving inter PMC transfer of chromatin material among neighbouring meiocytes (45.68%) was also observed. PMCs at anaphases/telophases showed laggards (31.25%) and chromatin bridges at A-I/T-I and A-II/T-II (21.02%) leading to abnormal microsporogenesis. Consequently, abnormal sporads such as triads (66.67%), polyads (3.33%) and triads with micronuclei (0.83%) were formed. Structural heterozygosity and inter PMC chromatin material transfer in the individuals of the species seem to be responsible for the reduction in pollen fertility (67.8%) and formation of pollen grains of heterogeneous sizes.