Study On Morphocytology Of The Development Of Anthers And Pollen Grains In Taigu Genetic Male Sterile Wheat

Wheat(Triticum aesitivum L.) is an important cereal crop worldwide, and wheat production plays important roles in food security in China. Male sterility is a common phenomenon in plants. Plant male sterility can be used to study hybrid vigor and to improve crop production. Therefore, study of wheat male sterility is important for cereal production.Wheat is a self-pollinated crop. The wheat male sterility can be used to prepare hybrid seeds, by which the artificial emasculation is not required, seed production cost will be reduced, and the seed purity can be enhanced. In this study, we examined the development of anthers and pollen grains in the ‘Taigu genic male sterile wheat using histological approaches. In addition, a number of male sterile barley(Hordeum vulgare L.) was studied and compared to the ‘Taigu wheat’. The main results were listed below.(1) In ‘Taigu wheat’, the pistil development appeared to be normal in both male-fertile and male-sterile plants, but the anther development was significantly different. Prior to the meiosis, there was no significant deference in anther development between male-fertile and male-sterile plants. From tetrad to microspore stages, anthers of the male-fertile plants remained a regular growth, but anthers of the male-sterile plants remained unchanged or even became smaller. When the pistil appeared to be mature, featured by an open stigma, the anthers of male-fertile plants reached 3.5mm in length, but the non-active anthers in the male-sterile plants was only 1.3mm in length, characterized by its arrow shape, gray white color, closed anthers, and no pollen grains.(2) An auricle distance(flag to penultimate leaves) was used to predict the development stage of wheat anthers. When the auricle distance was less than-3cm, the first floret of middle spikelet was at a stage with sporogenous cells. When the auricle distance was between-3 and-0.5cm, it is at a stage with pollen mother cells; while a range between-0.5 and 2cm corresponded to the meiosis stage, 2 to 3cm to the tetrad stage, 3 to 8cm to the single nuclear microspore stage, and 8 to 13 cm to the binuclear pollen stage. Prior to the microsporogenesis, the auricle distance appeared to be reliable for predicting the anther development stage in different wheat materials, but it became less correlated after the microspore stage. In addition, the length of young spikes and anthers can be used to estimate the development stage of wheat anthers. When the auricle distance reached 3cm, anther development in different spikelets were studied in the dwarf male sterile wheat ‘Lumai 15Ms2". The anther development in the middle of the spikelets were earlier than those in base and top spikelets. In each spikelet, anther development in different florets was also significantly different.(3) The development of anthers and pollen grains were studied in “Taigu wheat” with different genetic background. In general, the abortion of anther and pollen grains took place mainly between the pre-meiosis stage of the pollen mother cell to the single nuclear microspore stage. In Taigu wheat “Xiaoyan 6Ms2”, the abortion occurred primarily in the process of meiosis, and almost no microspore formed. In dwarf Taigu wheat “Lumai 15Ms2”, the abortion also occurred in meiosis; although some uninucleate microspores were found, and they soon became degraded.(4) We additionally evaluated eight male-sterile barley lines. They displayed similar phenomenon as discovered in “Taigu wheat”, but new types of male sterility and partial male sterility occurred in barley.