Cytological studies in two diploid mulberry varieties (Moraceae)

Abstract

Morus L. an economically important genus has more than 60 species distributed in both the Hemispheres. Chromosome number varies from 2n=28 to 2n=308 with ploidy level from x to 22x. In the present investigation two tetraploid mulberry varieties namely, Morus cathyana and M. macroura have been analyzed for detailed meiotic studies. Based on the chromosome configuration and other meiotic behaviour x = 14 has been considered as basic number of the genus. Meiosis was irregular. Various anomalies like univalents, bivalents, trivalents and quadrivalents are associated with nucleolus at diakinesis. Tetra, tri and bivalents in addition to univalents are noticed in metaphase I. Unequal separation of chromosomes are observed in anaphase I and II. Laggards and precocious movement of chromosomes at metaphase II and unoriented chromosomes at anaphase II have been observed.