Morphological and Ecological Adaptations, and Cytological Studies in Astragalus rhizanthus Royle ex Benth. (Papilionaceae), an Endemic to Himalayas

摘要

In the present investigation, we examined the morphological and ecological adaptations, and male meiosis and pollen fertility in an endemic species of genus Astragalus, A. rhizanthus Royle ex Benth. from cold deserts of Lahaul-Spiti district of Himachal, Pradesh, India. The three populations from Lahaul Valley and one from Spiti Valley depicted the same meiotic chromosome number of n=8 in all the accessions. In three populations (Lahaul, Sissu, 3170m, Chandartal Lake, 4300m; Spiti, Lossar, 3900m), meiosis was normal resulting into cent percent pollen fertility. However, in the accession from Lahaul Valley (Koksar, 3140m) majority of the pollen mother cells (PMCs) showed normal chromosome behaviour during meiosis-I and II. While, 12.09% PMCs showed the occurrence of chromatin material transfer involving 2-5 meiocytes during prophase-I, metaphases-I/ II, anaphases-I/II and telophases-I/II. Consequent to this, hypo- and hyperploid PMCs resulted. In certain cases, PMCs fused together to form syncytes which had two complements in the same cell. Pollen sterility was observed to be 9%. The paper also discusses morphological and ecological adaptations that the species has adopted to cope with the harsh and hostile environmental conditions prevailing in the cold deserts of Lahaul-Spiti.