Occurrence of hexaploid males in Dioscorea alata L.

In the polyploid species Dioscorea alata, earlier studies have shown a prevalence of higher ploidy levels (2n = 60 and 80) restricted among female clones. Cytological screening of a number of rare flowering collections maintained at the CTCRI revealed the occurrence of hexaploids (2n = 60) among male clones for the first time. The hexaploid males were sparse flowering, showing irregular meiosis leading to very high pollen sterility. On the basis of the diploid chromosome number 2n = 20 in the Old World Dioscorea, the trivalent forming 2n = 60 male is considered as an autoallohexaploid.