The Mutation of Rice MEDIATOR25, OsMED25, Induces Rice Bacterial Blight Resistance through Altering Jasmonate- and Auxin-Signaling

Abstract

Rice bacterial blight disease caused by Xanthomonas oryzae pv. oryzae (Xoo) is one of the most severe diseases of rice. However, the regulatory mechanisms of rice defense against Xoo remain poorly understood. The rice MEDIATOR25, OsMED25—a subunit of the mediator multiprotein complex that acts as a universal adaptor between transcription factors (TFs) and RNA polymerase II—plays an important role in jasmonic acid (JA)-mediated lateral root development in rice. In this study, we found that OsMED25 also plays an important role in JA- and auxin-mediated resistance responses against rice bacterial blight. The osmed25 loss-of-function mutant exhibited high resistance to Xoo. The expression of JA-responsive defense-related genes regulated by OsMYC2, which is a positive TF in JA signaling, was downregulated in osmed25 mutants. Conversely, expression of some OsMYC2-independent JA-responsive defense-related genes was upregulated in osmed25 mutants. Furthermore, OsMED25 interacted with some AUXIN RESPONSE FACTORS (OsARFs) that regulate auxin signaling, whereas the mutated osmed25 protein did not interact with the OsARFs. The expression of auxin-responsive genes was downregulated in osmed25 mutants, and auxin-induced susceptibility to Xoo was not observed in osmed25 mutants. These results indicate that OsMED25 plays an important role in the stable regulation of JA- and auxin-mediated signaling in rice defense response.

Jasmonic acid (JA)‐mediating MYB transcription factor1, JMTF1, coordinates the balance between JA and auxin signalling in the rice defence response

“…The gross morphology of the JMTF1-ox plants was examined. Rice These phenotypes have been observed in auxin-insensitive rice plants (Nakamura et al, 2006;Kitomi et al, 2012;Zhu et al, 2021;Suzuki et al, 2022). Thus, we next investigated the expression of selected auxin-responsive genes such as expansins (OsEXPs) and AUX/IAA (OsIAAs) genes in the JMTF1-ox plants.…”

“…Rice MEDIATOR25 (OsMED25), a subunit of the MEDIATOR multiprotein complex that acts as a universal adaptor between TFs and RNA polymerase II, interacts with OsMYC2 and positively regulates the expression of the OsMYC2‐responsive genes (Suzuki et al, 2021; Suzuki et al, 2022). Conversely, OsMED25 negatively regulates the expression of the OsMYC2‐independent JA‐responsive defence‐related genes (Suzuki et al, 2022).…”

“…Rice MEDIATOR25 (OsMED25), a subunit of the MEDIATOR multiprotein complex that acts as a universal adaptor between TFs and RNA polymerase II, interacts with OsMYC2 and positively regulates the expression of the OsMYC2‐responsive genes (Suzuki et al, 2021; Suzuki et al, 2022). Conversely, OsMED25 negatively regulates the expression of the OsMYC2‐independent JA‐responsive defence‐related genes (Suzuki et al, 2022). Rice NOVEL INTERACTOR OF JAZ (OsNINJA1) negatively regulates expression of the OsMYC2‐dependent defence‐related genes by forming a complex with JAZ proteins, and transgenic rice plants overexpressing OsNINJA1 are more susceptible to Xoo (Kashihara et al, 2019).…”

Exploring new strategies in diseases resistance of horticultural crops

“…A subunit of the mediator multiprotein complex, OsMED25, which serves as a important adaptor between transcription factors (TFs) and RNA polymerase II, and plays crucial roles in lateral root development mediated by jasmonic acid (JA) in rice. Loss of function OsMED25 mutants exhibit high resistance to Xoo through regulating JA-and auxin-signaling (Suzuki et al, 2022). Another Xoo-susceptibility locus, SPL33, encoding a eEF1A-like protein, which is used to trigger broad-spectrum and durable resistance against different pathogens including Xoo and M. oryzae (Wang et al, 2017).…”

Jasmonic Acid-Induced β-Cyclocitral Confers Resistance to Bacterial Blight and Negatively Affects Abscisic Acid Biosynthesis in Rice

“…Furthermore, infection with an avirulent Xoo strain induces thickening of the xylem secondary walls and reduces pit diameter in rice, thus resulting in the reduction of Xoo access to xylem parenchyma cells [ 16 ]. Lignin is an essential component of the response leading to the thickening of the xylem secondary walls and its accumulation is an important event to protect Xoo infection in rice [ 16 , 17 , 18 , 19 ]. Xoo -derived lipopolysaccharides induce upregulation of lignin biosynthesis genes in rice [ 20 ].…”