Studies On Microsporogenesis And Transcriptome Of Anthers Of A Nucleic Male Sterile Line Ms86-1in Sesame (Sesamum Indicum L.)

Sesame (Sesamum indicum L.,2n=26) is one of the most important oil-seed crops in the word with a ancient cultivate history. Osman and Yermanos first found a sesame nucleic male sterility (NMS) which was stable and completely sterile in1982. Researchers in Henan academy of agriculture sciences have improved the male sterile line since it had been discovered by Osman and Yermanos. They developed a new male sterile line ms86-1and successfully bred the fist hybrid (Yuzhi9) on the world by ms86-1cross with Danbackggae in late1980s. However, different types of fertility were observed in the reproduction of NMS, some plants from posterity of sib-cross produced trace pollens that complexed the maintaining of sterile character and the purity of hybrid, thereby hindered the popularized of sesame hybrid. In order to reveal the sterile mechanism sesame NMS ms86-1, we studied on the morphology of different fertility anthers, genetic law, microsporogenesis and the expressed sequences in mature anthers.The main results are as follows:1. Observation on ferility and genetic analysis of sesame NMS ms86-1Plants from posterity of sib-cross could be divided into two main types, fertility plants and sterility plants. The sterile plants could further divided into complete sterile plants and partial sterile plants. There were5.61%partial sterile plants in the population of sesame NMS sib-cross and13.68%in sterile plants. The proportion of partial sterile plants which derived from sib-cross of different NMS sterile plant was different obviously. The sterile plants in some sib-cross populations were all complete sterile, however, even more than30%parital sterile plants ever turned out in sib-cross populations too. There was no obvious difference among the flowers of three types of plants but the anthers. The anthers in fertile plants were plumper and white, and some pollen grains or bulks of pollen grains were appeared when squeezed the anthers. The anthers in sterile plants were flat and green or vestigial. The anthers of partial sterile plants had various appearances and been effected by the temperature. A few seeds could be getting from self pollination in the partial sterile plants but the setting percentage was very low.According to the primary hereditary analysis, the fertility of sesame NMS were mainly controlled by1pair major recessive allele and at least another pair of genes had a great impact on the fertility. The environment factors affected the fertility, especially the temperature had great impacts on the fertility of parital sterility plants.2. Microsporogenesis ultrastructure of sesame NMS ms86-1The microsporogenesis of fertile plants, sterile plants and partial sterile plants were observed under electron microscopes. Results showed that the microsporocytes with massive lipid globules in cytoplasm had vigorous metabolism at meiosis stage in fertile plants. The tapetal cells began degrade at tetrad stage and some ubisch bodies were secreted out of tapetal cell at microspore stage. There were a large number of ubisch bodies in pollen sac at the pollen maturation stage. The pollens were covered a layer mainly composed by probaculums with11-13bulged strips outside. The difference of microsporogenesis was observed at meiosis stage obviously in sterile plants. Unlike fertile plants, the lipid globules did not appear in cytoplasm, the callose began accumulate around the cell at meiosis stage and the tapetal cells did not degrade at tetrad stage and no ubisch body arose in the following development. The microspores were aborted at last without probaculums on the outside but callose. The development of microspore in partial sterile plants was better than those in the sterile plants. Lipid globules arose at meiosis stage and tapetal cells began degrade at microspore stage. The degraded cells provided nutrition and substances for the maturation of some microspores that were lagging behind in development and made these microspores turned out to be live gametes at last. These microspores were plumper than the aborted microspores and surrounded by a few ubisch bodies in pollen sac. However, they did not formed a layer covered the cells like the pollen grains.3. Analysis on gene expression of mature anthers in sesame NMS92and306sequences were10times higher expressed in the anther of fertile plants than in sterile plants and partial sterile plants. The expression of341and552sequences was10times lower than in sterile plants and partial sterile plants meanwhile. The gene express model of partial sterile anther was similar to that of sterile plants, only15sequences’expression was10times higher with16sequences’ expression10times lower when compared to the expressed sequences in the anther of sterile plants. There were43unique sequences in the anthers of fertile plants,2unique sequences in partial sterile plants and3sequences specially expressed in sterile plants. Results of gene ontology revealed the19sequences of the43unique sequences were related to polyprotein; the unique sequences in sterile plants were unkown and the2special sequences were related to lipid transfer protein and ubiquitin-60S ribosomal protein. GO functional classification showed the express level of relative genes of molecule function descended with the degree of sterile in anther rose. Partial sterile plants and sterile plants lacked the relative genes of virion part (GO:0044423) and viral infectious cycle (GO:0019058) which were highly expressed in fertile plants.