Cytological studies in some plants from cold deserts of India, Lahaul and Spiti (Himachal Pradesh)

Abstract

Detailed meiotic course and pollen fertility studies have been carried out in 23 species belonging to 14 families from the Indian cold deserts of Lahaul-Spiti. Out of these, new chromosome counts have been made in the three species, Chrysanthemum pyrethroides (2n=3x=27, 2n=4x=36), Waldhemia stoliczkai (n=9) and W. tomentosa (n=9). Meiotic course is abnormal in both the triploid and tetraploid cytotypes of C. pyrethroides which include univalents at metaphase, late disjunction of bivalents, formation of restitution nuclei at anaphase-I and chromatin bridges. Subsequently, microsporogenesis is also abnormal and is characterized by the occurrence of high frequency of monads, diads, triads, polyads, and micronuclei. These meiotic irregularities lead to high pollen sterility in both the cytotypes. Six species, Aquilegia fragrans (n=7), Astragalus bicuspis (n=8), Cicer microphyllum (n=8), Bergenia stracheyi (n=17), Sedum ewersii (n=11), Datisca cannabina (n=11) and Silene vulgaris (n=12) are worked out chromosomally for the first time from India. An additional/varied intraspecific aneuploid cytotype has been recorded in Hypericum elodeoides (n=9) against the earlier report of 2n=16 from other parts of India and elsewhere. The phenomenon of cytomixis involving inter PMC migration of chromatin material has been recorded in Anemone rivularis (n=8), Caltha palustris (n=16), Meconopsis aculeata (n=28) and Potentilla fruticosa var. rigida (n=7). Cytomixis in Anemone rivularis (n=8) and Caltha palustris (n=16) resulted into high percentage of pollen malformation and heterogenous sized fertile pollen grains. In the remaining species, the meiosis is perfectly normal leading to very high pollen fertility. Our counts for rest of the species substantiate the previous chromosome reports by other workers.