Pollen and seed fertility of the male fertile lines having the fertility restorer gene in three CMS systems of eggplant

Abstract

In our previous study, three pollen non-formation type cytoplasmic male-sterility (CMS) systems of eggplant (Solanum melongena L.) were developed through repeated backcrossing, by using wild Solanum species S. aethiopicum L. Aculeatum Group, S. anguivi and S. grandifolium as the cytoplasm donor and eggplant ‘Uttara’ as the recurrent pollen parent. Each CMS system has male fertile line which carries the fertility restorer genes for the pollen non-formation type sterility. In the present study, pollen and seed fertility of the male fertile lines were studied to find out the possibilities of selfing and anther culture for the development of homozygous restorer and male-sterile lines. To confirm the utility of these methods we tried to apply the method of selfing and anther culture of the male fertile lines. Pollen fertility was assessed by pollen stainability in acetocarmine, in Lugol's solution and in vitro germination rate of pollen at three different stages of pollen maturation, such as, 2 days before anthesis, at anthesis and 2 days after anthesis. Pollen stainability with acetocarmine and in vitro germination rate of pollen in all three stages of pollen maturation were comparatively lower in the male fertile lines than eggplant ‘Uttara’. At anthesis, pollen stainability was about 50% and in vitro pollen germination was less than 20% in three male fertile lines. Pollen stainability with Lugol's solution revealed that the low pollen fertility of the male fertile lines would be caused by incomplete accumulation and degradation of starch during pollen maturation. The male fertile lines showed good fruit set percentage and produced an adequate amount of seeds in selfing and backcrossing. A restorer line homozygous for the fertility restorer gene with the cytoplasm of S. anguivi was developed by selfing and selection of the male fertile line. A doubled haploid male sterile and male fertile plants were obtained from anther culture of the male fertile lines with the cytoplasms of S. anguivi and S. grandifolium, respectively. Pollen and seed fertility study of the present study revealed that homozygous restorer and male-sterile lines could be developed by selfing and anther culture of the male fertile lines of eggplant.