Rice Genomics and Genetics 2025, Vol.16, No.2, 86-95 http://cropscipublisher.com/index.php/rgg 89 3.4 Phenotypic effects of OsTms6 mutation What will happen if OsTms6 is knocked out? The answer is quite intuitive-pollen development will go wrong. For example, in the ostms18 mutant, the pollen wall cannot be formed at all, especially under high temperature conditions, and the sterility is very stable (Zhang et al., 2022). Not only that, this mutation will also cause the tapetum cells to "overgrow", as if they are suddenly out of control; at the same time, the starch in the anthers also decreases (Shi et al., 2022). When these changes are combined, the final result is that pollen cannot develop normally. In short, OsTms6 plays an indispensable role in maintaining normal pollen development, especially in maintaining fertility in hot environments. 4 Regulatory Mechanism of OsTms6 4.1 Transcriptional regulation 4.1.1 Promoter-related information If you want to understand how a gene "starts working", the promoter region is the key, and OsTms6 is no exception. This region is just in front of the gene and is a special DNA sequence with many "binding sites" that transcription factors can recognize. When different signals come, transcription factors may attach to it to start or inhibit the expression of OsTms6. Studying this part is actually to find out how it is regulated in different environments (Wu et al., 2019). 4.1.2 Related transcription factors But having a promoter alone is not enough, who will recognize it? At this time, transcription factors come in handy. They bind to the promoter region and determine whether OsTms6 is expressed or not. When studying the photothermosensitive male sterile line (PTGMS) of rice, some people noticed that some miRNAs, such as miR156, miR5488 and miR399, did not directly regulate OsTms6, but targeted certain transcription factors, thereby indirectly affecting the expression of genes related to male sterility (Sun et al., 2018; 2021). The regulatory relationship between these miRNAs and OsTms6 is very obvious, especially when encountering temperature fluctuations. 4.2 Post-transcriptional regulation 4.2.1 mRNA stability After OsTms6 is transcribed, whether its mRNA can be stable is also a very important thing. The regulation at this stage is more affected by miRNA. For example, some miRNAs (such as miR-2118 and miR-2275) will affect the generation of phasiRNA, and these phasiRNAs can regulate the stability of mRNA in rice reproductive organs (Ding et al., 2021; Shi et al., 2022). As a result, the stability of OsTms6 mRNA is affected, and the protein production changes accordingly. 4.2.2 Relationship between miRNA and siRNA Don't underestimate these small RNA molecules. Although miRNA and siRNA do not encode proteins themselves, they can accurately identify target mRNA and then either degrade it or prevent it from being translated. In the regulation of male fertility related to OsTms6, miR156, miR5488 and miR399 have been found to affect key genes in anther development (Sun et al., 2021). More complicatedly, proteins like AGO1d bind to miR2118 and miR2275 to guide the synthesis of phasiRNA (Shi et al., 2022). The whole system is like a network, and OsTms6 is just one link. 4.3 Environmental regulation 4.3.1 Effect of temperature When the temperature changes, the performance of OsTms6 also changes. Some sterile lines, such as Beijing sterile 366 (BS366), are prone to problems at low temperatures: the expression levels of miRNAs and their target genes change, which ultimately leads to abnormal pollen development and male sterility (Liu et al., 2022). Studies have also found that AGO1d also plays a role in this process, which again shows that temperature does not act alone, but affects the expression of OsTms6 through a series of molecular regulation (Shi et al., 2022).
RkJQdWJsaXNoZXIy MjQ4ODYzNA==