花生栽培种与野生种杂交不亲和障碍发生阶段研究OA

Interspecific hybridization incompatibility is a key limiting factor in the transfer and utilization of the beneficial genes from wild peanut species.In this study,two cultivars Silihong and Tifrunner were used as fe-male parents to cross with four wild species including Arachis duranensis(AA),A.magna(BB),A.cruziana(KK),and A.pusilla(HH),respectively,and the pollen germination,pollen tube growth,hybrid embryo development,and the reproductive processes of the F1 hybrids were observed in order to reveal the key stages of interspecific hybrid-ization incompatibility.At pollen germination stage,the pollen grains of all four wild species could germinate regu-larly on the stigma of the cultivated peanuts.At pollen tube growth stage,normal pollen tubes were observed when crossing with closely related wild species such as A.duranensis,A.magna,and A.cruziana;conversely,slower pol-len tube growth occurred when crossing with the distantly related wild species A.pusilla.At embryo or seed develop-ment stages,hybrid embryos derived from closely related wild species A.duranensis achieved a higher level of matu-rity but still needed embryo rescue to produce viable seedlings.In contrast,hybrid embryos from the distantly relat-ed wild species A.pusilla could not be successfully rescued.At the reproductive stage,since all hybrids were trip-loids,abnormal chromosome pairing and unequal chromosome segregation were observed at meiosis I and at ana-phase I respectively,resulting in high level of pollen sterility and no pod formation in hybrids F1.These findings sug-gest that there are almost no incompatibility barriers at the pollen germination stage between cultivated peanuts and these four wild species;however,a certain degree of incompatibility exists at the pollen tube growth stage specifical-ly between cultivated peanuts and distantly related wild species A.pusilla.The embryo developmental stage and the reproductive stage of interspecific hybrids F,are critical barriers for introgression of beneficial genes of wild species into cultivated peanut.