Male Meiosis, Microsporogenesis and Pollen Grain Study in Inula cuspidata C. B. Clarke (Asteraceae)

Abstract

Summary Male meiosis, microsporogenesis and pollen grain studies have been made on 11 accessions of Inula cuspidata C. B. Clarke from the cold desert regions of the Kinnaur district, Himachal Pradesh, India. All the accessions share the same meiotic chromosome number nϭ10. Out of these, 10 accessions show regular chromosome pairing resulting into normal 10 bivalents formation. The meiotic analysis in these accessions reveals that 2 bivalents are of comparatively large size. These large-sized bivalents in 6 accessions show abnormalities in their disjunctions resulting into laggards/bridges during anaphases/telophases and micronuclei in tetrads and consequently some pollen sterility. In one of the accessions of I. cuspidata scored from Tapri, meiotic course is irregular due to the presence of a high frequency of univalents during the first meiosis. These univalent chromosomes during subsequent stages of meiosis fail to organize at the spindle plate and remain scattered in the cytoplasm. Consequently, the majority of the PMCs in the accession depict irregular anaphases/telophases, formation of multiple nuclei and abnormal sporads (dyads, triads, polyads and tetrads with micronuclei). The accession forms a large number of malformed pollen grains consisting of unstained/sterile and heterogeneous sized stained/fertile pollen grains. The accession showing such a abnormal meiotic behaviour could be attributed to its hybrid nature where the chromosome of the 2 putative parents is left unpaired during earlier stages of prophase I.