Studies on interspecific hybridization with particular reference to development of male sterility insesme Sesamum indicum L

Abstract

The present investigation was taken up with two cultivars (DS-1 and E-8) of S. newlineindicum and five wild species viz., S. malabaricum, S. mulayanum, S. prostratum, S. radiatum newlineand S. occidentale to identify and overcome the crossability barriers and to study the newlinepossibility of introgressing male sterility into cultivated species of sesame. newlineThe identification of fertilization barriers in interspecific crosses with studies of in vivo newlinepollen germination, pollen tube growth in pistil using fluorescence microscopy with aniline newlineblue stain it was found that none of the crosses had pre-fertilization barriers. newlineThe seeds of crosses S. radiatum x S. indicum and S. occidentale x S. indicum failed newlineto germinate even in culture media due to the presence of post-fertilization barriers as newlineindicated by fluorescent microscopic study which showed good per cent of ovule having newlinemicropylar penetrations. Therefore, ovule culture was used to rescue these interspecific newlineembryos in which an increase in ovule germination percentage was achieved as age of the newlineovule increased upto 12 days after pollination in half MS medium. newlineThe F1 hybrids in which significant sterility per cent was observed were confirmed for newlinehybridity using morphological observations like flower colour and further supplemented with newlinecytological and molecular studies. The cytological studies of two sterile F1 hybrids (S. newlinemalabaricum x E8-4 and S. mulayanum x E8-8) though showed chromosome segregation newlineabnormalities, cells with normal tetrad formation were seen at the end of meiosis. The male newlineparent specific RAPD bands successfully confirmed the hybrid nature of S. malabaricum x newlineE8-4 and S. mulayanum x E8-8. newlineSignificant sterility per cent of 24.64 and 19.99 was observed in the F1 s of S. newlinemalabaricum x E8-4 and S. mulayanum x E8-8, respectively. Also significantly higher sterility newlinepercentage compared to their corresponding F1 hybrids was achieved upon backcrossing of newlinesterile F1 s to cultivated parents whereas sterility percentage drastically reduced when sterile newlineF1 s were back crosse