OsWRKY67 positively regulates blast and bacteria blight resistance by direct activation of PR genes in rice

Abstract Background WRKY proteins are one of the largest gene families and are well-known for their regulatory roles in many aspects of plant development, including plant response to both biotic and abiotic stresses. Although the roles of WRKY proteins in leaf blast resistance have been well-documented in rice, their functions in panicle blast, the most destructive type of blast disease, are still largely unknown. Results Here, we identified that the transcription of OsWRKY67 was strongly activated by leaf and panicle blast infection. OsWRKY67 is ubiquitously expressed and sub-localized in the nucleus. Rice plants overexpressing OsWRKY67 showed quantitatively enhanced resistance to leaf blast, panicle blast and bacterial blight. In contrast, silencing of OsWRKY67 increased the susceptibility to blast and bacterial blight diseases. RNA-seq analysis indicated that OsWRKY67 induces the transcription of a set of defense-related genes including the ones involved in the salicylic acid (SA)-dependent pathway. Consistent with this, the OsWRKY67-overexpressing plants accumulated higher amounts of endogenous SA, whereas lower endogenous SA levels were observed in OsWRKY67-silenced plants relative to wild-type Nipponbare plants before and after pathogen attack. Moreover, we also observed that OsWRKY67 directly binds to the promoters of PR1a and PR10 to activate their expression. Conclusions These results together suggest the positive role of OsWRKY67 in regulating rice responses to leaf blast, panicle blast and bacterial blight disease. Furthermore, conferring resistance to two major diseases makes it a good target of molecular breeding for crop improvement in rice

The MKKK62-MKK3-MAPK7/14 module negatively regulates seed dormancy in rice

Abstract Background Seed dormancy directly affects the phenotype of pre-harvest sprouting, and ultimately affects the quality and yield of rice seeds. Although many genes controlling seed dormancy have been cloned from cereals, the regulatory mechanisms controlling this process are complex, and much remains unknown. The MAPK cascade is involved in many signal transduction pathways. Recently, MKK3 has been reported to be involved in the regulation of seed dormancy, but its mechanism of action is unclear. Results We found that MKKK62-overexpressing rice lines (OE) lost seed dormancy. Further analyses showed that the abscisic acid (ABA) sensitivity of OE lines was decreased. In yeast two-hybrid experiments, MKKK62 interacted with MKK3, and MKK3 interacted with MAPK7 and MAPK14. Knock-out experiments confirmed that MKK3, MAPK7, and MAPK14 were involved in the regulation of seed dormancy. The OE lines showed decreased transcript levels of OsMFT, a homolog of a gene that controls seed dormancy in wheat. The up-regulation of OsMFT in MKK3-knockout lines (OE/mkk3) and MAPK7/14-knockout lines (OE/mapk7/mapk14) indicated that the MKKK62-MKK3-MAPK7/MAPK14 system controlled seed dormancy by regulating the transcription of OsMFT. Conclusion Our results showed that MKKK62 negatively controls seed dormancy in rice, and that during the germination stage and the late stage of seed maturation, ABA sensitivity and OsMFT transcription are negatively controlled by MKKK62. Our results have clarified the entire MAPK cascade controlling seed dormancy in rice. Together, these results indicate that protein modification by phosphorylation plays a key role in controlling seed dormancy

MicroRNA-140-5p inhibits hepatocellular carcinoma by directly targeting the unique isomerase Pin1 to block multiple cancer-driving pathways

Hepatocellular carcinoma (HCC) is the second leading cause of cancer related-death. As a major common regulator of numerous cancer-driving pathways and a unique therapeutic target, the prolyl isomerase Pin1 is overexpressed in a majority of HCCs, whereas the mechanism underlying Pin1 overexpression remains elusive. Here we find that miR-140-5p inhibits HCC by directly targeting Pin1 to block multiple cancer-driving pathways. Bioinformatics analysis, miRNA binding and functional assays identify that miR-140-5p directly interacts with the 3′UTR of Pin1 and inhibits Pin1 translation. Furthermore, like stable Pin1 knockdown, moderate overexpression of miR-140-5p not only eliminates Pin1, but also inhibits cells growth and metastasis. Importantly, these effects of miR-140-5p are largely rescued by reconstitution of Pin1. Moreover, miR-140-5p inhibits multiple Pin1-dependent cancer pathways and suppresses tumor growth in mice. The clinical significance of these findings has been substantiated by the demonstrations that miR-140-5p is frequently down-regulated and inversely correlated with Pin1 overexpression in HCC tissues and cell lines. Given prevalent miR-140-5p downregulation in other cancers and major impact of Pin1 overexpression on activating numerous cancer-driving pathways including global miRNA downregulation, the miR-140-5p/Pin1 axis may play a major role in tumorigenesis and offer promising therapeutic targets for HCC and other cancers