Polyploidy and sterility in relation to sex in Dioscorea alata L. (Dioscoreaceae)

Abstract

Chromosome numbers and fertility studies of 73 male and 30 female flowering germplasm accessions of Dioscorea alata L. were carried out. All males were tetraploids showing the same chromosome number (n = 20 or 2n :-40) and were pollen fertile (10.9-96.2%), most of them being highly fertile. Among the female the majority were higher ploids (hexa-and octoploids; 2n = 60 and 80) and sexually completely sterile. There were only two tetraploid female accessions which were sexually fertile. Pollination studies revealed that seed sterility in D. alata was due to female sterility associated with the occurrence of higher levels of ploidy. The female sex-limited occurrence of higher polyploidy and sterility observed in D. alata is a curious situation among dioecious higher plants.

Cytogenetic characterization of Aloysia virgata Ruiz and Pavan (Verbenaceae)

“…These alterations have been related to polyploidy. Cytological evidence for an association between sterility and a high level of ploidy was also reported by Abraham and Gopinathan (1991) for Dioscorea alata L. (Dioscoreaceae). Khoshoo and Mahal (1967), Natarajan and Ahuja (1957) and Raghavan and Arora (1960) found meiotic irregularities and seed sterility in Lantana populations in India.…”

Ploidy level studies on the Dioscorea cayenensis/Dioscorea rotundata complex core set

“…Considering the higher ploidy levels observed in D. cayenensis, one could hypothesize that hexaploidy or octoploidy could favor male flowering, while tetraploidy would favor female flowering in both species. In D. alata the opposite was observed, with higher ploidy levels (hexaploidy and octoploidy) being restricted to females (Ramachandran 1968;Abraham and Nair 1991;Abraham 1998). The biological interplay that drives the relationship between polyploidy and sex is not clearly understood and represents an interesting topic for future studies.…”

Yam Breeding in Ghana

“…alata is also known to exhibit different levels of ploidy, including diploid (2× = 40), triploid (3× = 60), and tetraploid (4× = 80) forms within the species (Abraham & Nair, 1991;Gamiette et al, 1999;Egesi et al, 2002;Arnau et al, 2009;Babil et al, 2010;Obidiegwu et al, 2010). Babil et al (2010) reported that three levels of ploidy, diploid, triploid, and tetraploid, were identified in a landrace collection of water yam from Myanmar.…”