Deciphering the meiotic behaviour in species of genus Artemisia from Cold Deserts of Ladakh (Jammu & Kashmir)

Abstract

Present study reports the chromosome counts and meiotic analysis including microsporogenesis and pollen fertility in 10 species of the genus Artemisia from the cold deserts of Ladakh in the state of Jammu and Kashmir for the first time. We here add the chromosome record for species, A. desertorum for the first time from India which also includes the new intraspecific hexaploid cytotype (2n = 54) for A. desertorum. The study also reports the presence of B-chromosomes for A. gmelinii. The course of meiosis in most of the accessions was observed to be regular except for some individuals of A. absinthium, A. desertorum, A. gmelinii, and A. sieversiana which showed certain meiotic abnormalities in meiocytes involving cytomixis, chromatin stickiness, chromatin bridges, lagging chromosomes and late segregation of bivalents and consequently irregular sporads and sterile pollen grains. The genus Artemisia shows a considerable heterogeneity in chromosome numbers varying from 2n = 14 to 2n = 144. The genus exhibits several base numbers (x = 7, 8, 9, 11, 17) but x = 9 is regarded as the most common and favoured basic number. The next favoured base number is x = 8. On the otherhand, other basic numbers, x = 7, 11 and 17 are rather less common. The affect of polyploidy in genus evolution seems to be quite significant as 52.12 % of the species exists at various ploidy levels (3x, 4x, 5x, 6x, 8x, 10x, 12x, 14x). Aneuploidy causing chromosome variation in the genus is equally important from the existence of intraspecific aneuploid/ dysploid cytotypes.