Development of a new CMS system in pigeonpea utilizing crosses with Cajanus lanceolatus (WV Fitgz) van der Maesen

Abstract

Cytoplasmic male sterility is an important biological tool which is now available to pigeonpea breeders to exploit heterosis/hybrid vigor. A variety of CMS systems have been developed when wild relatives of pigeonpea from different gene pools were crossed as the female parent with cultivated types as the male parent. This paper reports a second source of CMS developed by using the cultivated pigeonpea as the female parent and one of its wild relative Cajanus lanceolatus (WV Fitgz) van der Maesen as the pollen donor, as such the A5 CMS system derived from C. acutifolius. All the F₁ hybrids were evaluated to confirm hybridity using 27 simple sequence repeat (SSR) markers. SSR marker analysis of parents provided 17 polymorphic markers from a total of 27 SSR markers used. Subsequently polymorphic SSRs were used to confirm the hybridity of the F₁ plants. F₁ hybrid plants were crossed with a range of pigeonpea cultivars to identify maintainers of male sterility. Morphology of the F₁ and backcross generations, cytology of the sterile as well as fertile floral buds derived from the crosses between sterile F₁ hybrids and unrelated pigeonpea cultivars were studied. An important observation made was that male sterility was a post meiotic process. Microsporogenesis was normal until the tetrad stage, but none of them formed pollen grains. Instead, they grouped together within the pollen mother cell wall and the tetrads did not separate into individual pollen grains.