Pollen fertility and cytological observation of a thermosensitive genic male sterile line of non-pollen type XianS in rice(Oryza sativa L.)

XianS,a new thermosensitive genic male sterile(TGMS)line of non-pollen type in rice,was obtained from a spontaneous mutant of Xianhuangzhan,a good quality indica variety.The pollen fertility in XianS was mainly determined by temperature.In Guangzhou(23°08′N),XianS had pollen sterility in early May to late October.Under controlled conditions,XianS only had 5% stainable pollens under 21℃(day mean temperature) for 7d or 23.5℃(day mean temperature) for 15d,and showed complete pollen sterility when daily mean temperature was high than 24℃.Therefore,the male sterility of XianS was stable,and was safe to produce two line hybrid rice.Cytological observations of XianS at various developmental stages indicated that the pollen abortion mainly occurred at meiosis stage.The microsporocyte became vacuolate and agglutinate,arrested meiotic division at the leptotene stage of meiosis,underwent amitosis and abnormal cytokinesis,and failed to give rise to normal tetrad,but formed different size cells with variable numbers of nuclei.These abnormal cells disappeared eventually due to vacuolization or protoplasm degeneration,resulting in no pollen in the mature anthers.The pattern of pollen abortion in XianS was different from all of the PTGMS rice reported.