Molecular Plant Breeding 2024, Vol.15, No.6, 429-441 http://genbreedpublisher.com/index.php/mpb 431 Figure 1 Models of the current understanding for the three cloned EGMS genes (Adopted from Fan and Zhang, 2017) Image caption: a. An lncRNALDMAR controls the PGMS trait at the PMS3 locus. A small RNA psi-LDMAR generated from the promoter mediated the DNA methylation of LDMAR regulating the level of transcript for pollen development under long-day conditions. Or alternatively, a G-to-C mutation leads to a loss of-function of small RNA osa-smR5864m in targeting different genes, resulting in PGMS. b. An lncRNAPMS1T targeted by the miR2118 confers the PGMS at the PMS1 locus. The SNP nearby the cleavage site may influence the cleavage efficiency for higher accumulation of phasiRNAs, causing male sterility in 58S under long-day conditions. c. The TGMS gene TMS5 encodes RNase ZS1 processing UbL40 mRNA whose expression is temperature-sensitive. The loss-of-function mutation of RNase ZS1 results in the overaccumulation of UbL40 mRNA, leading to male sterility at high temperature. LD, long-day conditions; SD, short-day conditions; HT, high temperature; LT, low temperature (Adopted from Fan and Zhang, 2017) 3 Light Regulation of MS Genes 3.1 PGMS in rice PGMS in rice is a critical trait for hybrid rice breeding, as it allows for the production of MS lines under specific daylength conditions. The PGMS trait is controlled by various genetic loci, such as PMS1 and PMS3, which encode long noncoding RNAs essential for male fertility under long-day conditions (Fan and Zhang, 2017). The carbon starved anther (csa) mutant is another example of a PGMS line (Zhang et al., 2013), where the CSAgene plays a pivotal role in regulating sugar metabolism and cell wall synthesis in anthers under short-day conditions (Figure 2) (Li et al., 2022). Additionally, the pms3 locus, which encodes the long non-coding RNA LDMAR, is crucial for normal male fertility under long-day conditions, with increased methylation in its promoter leading to MS (Ding et al., 2012).
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