Rice Genomics and Genetics 2025, Vol.16, No.2, 86-95 http://cropscipublisher.com/index.php/rgg 88 3 Molecular Functions of OsTms6 3.1 Gene structure and protein function The gene OsTms6 is closely related to temperature-sensitive male sterility (TGMS) in rice. It actually encodes a protein called GMC oxidoreductase, which is related to molecules such as glucose, methanol, and choline. However, what really makes it a research focus is a small mutation: Gly becomes Ser (Zhang et al., 2022). This point mutation directly leads to the TGMS trait. Under high temperature conditions, the pollen wall develops abnormally (Figure 1). Interestingly, this gene itself is also regulated by another key factor, OsMS188, which is a transcription factor in the tapetum and is also linked to the development of the pollen wall (Zhang et al., 2022). Understanding the structure of OsTms6 and what it does is the key to figuring out why rice exhibits sterility or restores fertility at different temperatures. Figure 1OsTMS18encodes an anther-expressed GMC oxidoreductase (Adopted from Zhang et al., 2022) Image caption: (a) SNP index for mapping the OsTMS18 by the BSA-seq approach. (b) Identification of the mutated point of OsTMS18in a WT plant and ostms18 (Adopted from Zhang et al., 2022) 3.2 Expression pattern of OsTms6 The location of OsTms6 expression is also very particular, mainly concentrated in the anther wall cells, especially in the period before and after meiosis. To put it bluntly, it is "full-time" to do the reproductive work. When the temperature rises, its expression will be enhanced, like "emergency" to help stabilize the vitality of pollen (Lin et al., 2023). But this process is not fixed, it is also affected by the environment, such as temperature fluctuations (Shi et al., 2022). So the expression of this gene is like a temperature sensor. Once the external environment changes, its expression level will also adjust accordingly, which will affect the survival status of pollen. 3.3 Functional studies in model plants Regarding the function of OsTms6, scientists have not only studied it in rice, but also found its "relatives" in Arabidopsis. It turns out that the genes in this family seem to be a bit "afraid of heat". For example, in Arabidopsis, once the temperature rises, the mutants of homologous genes will also show a decrease in fertility (Zhang et al., 2022). This is even more obvious in rice. The mutation directly leads to TGMS, and the pollen wall cannot be formed. The pollen will be useless if it is hot. Similar phenomena occur in different plants, indicating that the function of this gene is very conservative, and it may have been involved in regulating male fertility since a long time ago. This feature is of great significance for hybrid breeding.
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