Chromosome numbers and meiotic behavior in some species of Asteraceae from high altitudinal regions of Kashmir Himalayas

Abstract

Disparity or continuity in the chromosome count within taxa of various categories has been verified to be an imperative character for taxonomic classification. Male meiotic studies in 64 species (161 accessions) of composits from geographically isolated regions were examined in detail in order to update the existing knowledge of meiotic chromosome numbers of composits from the outer part of the Himalayas. Myriactis javanica (2 n = 36) and Tanacetum nubigenum (2 n = 36) have been counted chromosomally for the first time at the world level. Besides, Koelpinia linearis (2 n = 36), Ajania fruticulos a (2 n = 18), Crepis flexuosa (2 n = 14), and Tanacetum gracile (2 n = 18) have been analyzed chromosomally for the first time from India. New intraspecific diploid/polyploid cytotypes are added for Artemisia desertorum (2 n = 6 x = 54), Carduus nutans (2 n = 4 x = 16), Erigeron annuus (2 n = 2 x = 18), Leontopodium jacotianum (2 n = 4 x = 48), Pentanema indicum (2 n = 6 x = 54), Scorzonera virgata (2 n = 2 x = 16), and Tragopogon pratensis (2 n = 2 x = 12). Besides, eight species have been evaluated cytologically for the first time from Kashmir Himalayas. Various meiotic abnormalities like cytomixis, structural heterozygosity, chromatin stickiness, nonsynchronous disjunction, laggards, bridges, unoriented chromosomes leading to pollen sterility have been observed for the first time in some species. The presence of B-chromosomes has been detected in Achillea millefolium (2 n = 18+0-1B) and Saussurea candolleana (2 n = 26+0-1B). Among meiotically analyzed species, diploids (76.5%) and polyploids (23.5%) prevail. • During the present work, detailed chromosomal analysis has been carried in plants of family Asteraceae from unexplored regions of the Himalayas.- • The meiotic behavior of each species was analyzed in detail, and the effect of the meiotic abnormalities on pollen fertility was studied. • The interesting results in the form of cytomixis, translocation, and chromosome stickiness were detected for the first time in some species. • The percentage of polyploidy in species of family Asteraceae was also observed in the high altitudinal regions of the Himalayas. • B-chromosomes were also observed in few species.