| The exploration of the mechanism of plant male sterility has been an active research area. It is also a fundamental research for plant heterosis utilization. Male sterility wheat induced by chemical hybridizing agents has many characteristics, such as convenient, flexible, time saving and labor saving. It also does not need to look for restorer to produce seed. SQ-1 is a new wheat chemical hybridizing agent which is developed by Chinese scientists. The normal wheat can become that of male sterile when spray appropriate doses of SQ-1 at the right time, and proportion of male sterile wheat can reach 95%-100%. In recent years, the researchers have studied on the mechanism of male sterility induced by chemical hybridizing agents SQ-1 in wheat, and it also have obtained certain research progress. It is generally believed that the male sterility mechanism focuse on tapetum, callose, energy metabolism, material metabolism, programmed cell death, etc.Actin filaments play an important role in vital movement, such as plant top growth, cyclosis, cell division, organelle movement, etc. So anything that can make the organization of actin filaments abnormal can lead to the abnormal growth of plants. Previous research results showed that actin filaments have a close relationship with pollen sterility in the cell division process. However, the studies of actin filaments in physiological male sterile wheat are less. So the organization of actin filaments and callose and the expression of related genes in physiological male sterility wheat pollen cells are researched to reveal the relationship between actin filaments and callose and pollen abortion in physiological male sterility wheat. Then it can provide more comprehensive understanding on the mechanism of male sterility induced by chemical hybridizing agents.In this research, we used the physiological male sterility line ms(A)-Xinong1376 and corresponding normal fertile wheat(A)-xinong1376 as test materials. The TRITC-phalloodin was used to staining actin filaments and Aniline blue was used to staining callose. Then we observed the organizating of actin filaments and callose in pollen mother cell during meiosis. At the same time, QRT-PCR was used to analyze the expression of TaADF(Actin depolymerizing factor) and TaGSL(Glucan synthase-like). In brief, the main results were as follows:(1) The fertility of male sterility induced by chemical hybridization agents SQ-1 was investigated. The results showed that the male sterility rate was 95%-100% and the development of pistil was not affected. So it can be used as materials in the next experiments.(2) At prophase I, metaphase I, anaphase I, there were no significant differences between physiological male sterility and male fertility. At early telophase I, we observed that there were no sharp actin filaments at leading edges of phragmoplasts and the overlapped actin filaments at midline were obscure in physiological male sterility. At late telophase I, there was a cell plate at the midline of phragmoplast, it was linear and smooth, but in the physiological male sterile line, the linear cell plate was not seen, the midzone of dyads was hollow. At tetrad, actin filaments were obscure and had no silky feeling.(3) At late telophase I, the deposition of callose on the cell plate was insufficient and the cell plate was wrinkled and cleft. At tetrad, the callose fluorescence was weaker in the physiological male sterile.(4) Then qRT-PCR technique was performed to analyze the expression patterns of the TaADF gene and TaGSL gene in sterile and fertile anthers during meiosis. The results indicated that the transcript of TaADF in the treated anthers was 4.28 times higher than that of the control. It indicated that because of the increase expression of TaADF, the rate of dissociation of actin filaments was increased, so the microfilaments were obscure. The transcript of TaGSL in the treated anthers was 0.83 times lower than that of the control. Callose deposition was influenced by SQ-1.In conclusion, it was likely that SQ-1 treatment caused the increased expression level of TaADF. Then the increased expression level of TaADF in the physiological male sterility line destroyed the normal structure of actin filaments. So the actin filaments cannot execute their functions. Then it may influence certain metabolic pathways associated with fertility in anther development. At the same time, abnormal actin filaments caused abnormal cell plate formation which may have an affect on callose deposition. Therefore it was estimated that it has a close relationship among the changes of actin filaments and callose and the physiological male sterility induced by SQ-1. |
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