Genomics and Applied Biology 2024, Vol.15, No.4, 200-211 http://bioscipublisher.com/index.php/gab 206 reduced free SA content and decreased BPH resistance (SA-R # 256) resulting from T-DNA insertion in the first exon of the R2R3 MYB transcription factor OsMYB30 (Figure 2). Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis demonstrated that at 3 and 6 hours following BPH infection, the transcript level of OsMYB30 in wild-type plants exhibited a notable induction, whereas no such induction was observed in OsMYB30 mutant plants. Furthermore, the mutant system exhibited a notable reduction in lignin content. Furthermore, the induction of OsPAL6 and OsPAL8 expression by BPH was absent in the mutant line. The results suggest that OsMYB30 may regulate the expression of OsPALin response to BPH infection. OsMYB60 is another R2R3-MYB transcription factor that has been the subject of study about its role in leaf morphology. Similarly to OsMYB30, OsMYB60 plays a role in maintaining the flattening of the leaf blade. The interaction between OsMYB60 and TL is of great significance to this process. As demonstrated by Liu et al. (2018), the overexpression of OsMYB60 results in the formation of twisted leaf blades (Figure 3), indicating that precise regulation of OsMYB60 is necessary for the normal development of leaves. Moreover, OsMYB60 interacts with the C2H2 transcription factor OsZFP7, which further corroborates its involvement in leaf morphological development. 8 Future Perspectives and Opportunities 8.1 Advances in genomic technologies The rapid advancement in genomic technologies has significantly enhanced our understanding of the genetic basis of complex traits in rice, including the R2R3-MYB gene family. Whole genome sequencing and comparative genomic analysis have revealed a multitude of allelic variations that are unique to specific rice landraces. These include Purpleputtu, which exhibits unique traits such as purple coloration due to specific genetic variations (Lachagari et al., 2019). These technologies facilitate the identification of pivotal regulatory genes and their variants, thereby providing a comprehensive perspective on the genetic architecture that underlies significant agronomic traits. It is recommended that future research focus on leveraging these advanced genomic tools to further dissect the functional roles of R2R3-MYB genes in rice. This will facilitate the development of high-throughput genotyping platforms for precise genetic mapping and trait association studies (Zhao et al., 2011; Gu et al., 2022). Figure 2 OsPALs-mediated BPH resistance is regulated byOsMYB30(Adopted from He et al., 2019) Image caption: (A) Representative image of Osmyb30 mutants infested with BPH for 5 d. (Scale bars, 1 cm.) (B) Seedling mortality rates of WT and Osmyb30 mutants infested with BPH. Data were collected at 7 dpi. (C) Verification of the T-DNA insertion in the Osmyb30 mutant. The positions of the F, R, and TF primers are indicated as red arrows. (D) SA levels in WT and the Osmyb30 mutant plants. (E) Histochemical staining showing lignin accumulation in fresh leaf sheaths of WT and the Osmyb30 mutant plants. (Scale bar, 50 μm.) (F) qRT-PCR analysis of OsPAL6 and OsPAL8 expression in the Osmyb30 mutant. The expression values are presented relative to those in WT without BPH infestation. Error bars, mean ± SD of 3 biological replicates, by Student’s t-test (B and D, **P < 0.01) (Adopted from He et al., 2019)
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