Phenomenon of cytomixis and intraspecific polyploidy (2x, 4x) in Spergularia diandra (Guss.) Heldr. & Sart. in the cold desert regions of Kinnaur district (Himachal Pradesh).

摘要

Spergularia diandra (Guss.) Heldr. & Sart. (Family: Caryophyllaceae), worked out presently from the valleys of Ganjul and Hangrang in the Kinnaur district of Himachal Pradesh, exhibits intraspecific diploid (2x=n=9) and tetraploid (4x=n=18) cytotypes. The species has been worked out chromosomally for the first time from India and adds a new 4x cytotype to the already existing 2x cytotype known from outside of India. The individuals of 2x cytotype are restricted to the Ganjul Valley while those of 4x cytotype are present in Hangrang valley. The individuals of the 2x and 4x cytotypes could be distinguished on the basis of habit, plant size, number of branches, bushy nature, and fleshiness and size of leaves. The diploid plants showed spindle abnormalities during meiosis resulting into heterogeneous sized fertile/stained pollen grains and some pollen sterility (10.00-12.00%). On the other hand, some plants of 4x cytotype showed the phenomenon of cytomixis involving chromatin transfer among proximate meiocytes, and chromatin stickiness resulting into 5.00-8.00% unstained/sterile pollen grains. The cytomixis in the 4x cytotype is the first ever record for the species and seems to be a natural phenomenon under direct genetic control as the plants with and without cytomixis grow under the same environmental conditions.