掲載種別：研究論文（学術雑誌）   出版者・発行元：Oxford University Press (OUP)  

Abstract

Plants activate pattern-triggered immunity (PTI) through key immune components, including pattern recognition receptors (PRRs), receptor-like cytoplasmic kinases (RLCKs), and transcription factors (TFs), to combat pathogens. However, a comprehensive transcriptional overview of these immune regulators at the subfamily level during biotic stress in rice is currently lacking. The aims of this study were to characterize the expression profiles of OsPRRs, OsRLCKs, and OsTFs and establish a robust pipeline for selecting novel candidate genes involved in plant immunity. We identified differentially expressed genes (DEGs) within these families using transcriptomic data from both rice plants infected with Magnaporthe oryzae infection and rice suspension cell treated with chitin treatment. Our analysis revealed the transcriptional regulation of well-known immune-related subfamilies of OsPRRs, OsRLCKs, and OsTFs, such as RLK-LRR-XII and RLCK-VII, and identified several novel subfamilies with high proportions of DEGs that may contribute to pathogen perception and plant defense. We demonstrated that selecting candidates from overlapping DEGs between plant and suspension cell systems is an effective strategy for screening genes involved in rice immunity. Using this pipeline, novel immune regulators were identified, and their functions were confirmed. Two RLCKs, i.e., OsRLCK298 and OsBSR1, act as positive regulators of immunity against rice blast fungus, whereas two transcription factors, i.e., OsERF65 and OsERF96.2, act as negative regulators. This study provides a valuable transcriptomic resource and establishes a validated pipeline for gene discovery that could be applied to other stress responses and in other plant species.

DOI： 10.1093/pcp/pcag019

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

NLR family proteins act as intracellular receptors. Gene duplication amplifies the number of NLR genes, and subsequent mutations occasionally provide modifications to the second gene that benefits immunity. However, evolutionary processes after gene duplication and functional relationships between duplicated NLRs remain largely unclear. Here, we report that the rice NLR protein Pit1 is associated with its paralogue Pit2. The two are required for the resistance to rice blast fungus but have different functions: Pit1 induces cell death, while Pit2 competitively suppresses Pit1-mediated cell death. During evolution, the suppression of Pit1 by Pit2 was probably generated through positive selection on two fate-determining residues in the NB-ARC domain of Pit2, which account for functional differences between Pit1 and Pit2. Consequently, Pit2 lost its plasma membrane localization but acquired a new function to interfere with Pit1 in the cytosol. These findings illuminate the evolutionary trajectory of tandemly duplicated NLR genes after gene duplication.

DOI： 10.1038/s41467-024-48943-5

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Small signalling peptides play important roles in various plant processes, but information regarding their involvement in plant immunity is limited. We previously identified a novel small secreted protein in rice, called immune response peptide 1 (IRP1). Here, we studied the function of IRP1 in rice immunity. Rice plants overexpressing IRP1 enhanced resistance to the virulent rice blast fungus. Application of synthetic IRP1 to rice suspension cells triggered the expression of IRP1 itself and the defence gene phenylalanine ammonia-lyase 1 (PAL1). RNA-seq results revealed that 84% of genes up-regulated by IRP1, including 13 OsWRKY transcription factors, were also induced by a microbe-associated molecular pattern (MAMP), chitin, indicating that IRP1 and chitin share a similar signalling pathway. Co-treatment with chitin and IRP1 elevated the expression level of PAL1 and OsWRKYs in an additive manner. The increased chitin concentration arrested the induction of IRP1 and PAL1 expression by IRP1, but did not affect IRP1-triggered mitogen-activated protein kinases (MAPKs) activation. Collectively, our findings indicate that IRP1 functions as a phytocytokine in rice immunity regulating MAPKs and OsWRKYs that can amplify chitin and other signalling pathways, and provide new insights into how MAMPs and phytocytokines cooperatively regulate rice immunity.

DOI： 10.1093/jxb/erac455

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

To utilize a transposon-tagged mutant as a breeding material in rice, an endogenous DNA transposon, nDart1-0, was introduced into Koshihikari by successive backcrossing together with aDart1-27, an active autonomous element. The founder line for nDart1-tagged lines of Koshihikari carried nDart1-0 on chromosome 9 and transposed nDart1-12s on chromosomes 1 and 8 and nDart1-3 on chromosome 11. In nDart1-tagged lines, there were the most abnormal phenotypic mutants and many aberrant chlorophyll mutants at seedling stage. At mature stage, many semi-sterile mutants were observed. Dwarf, reduced culm number and lesion mimic mutants were also found. In total, 43.2% of the lines segregated some phenotypic mutants. Thus, the nDart1-tagged lines of Koshihikari are expected to be potentially useful for screening stress-tolerant mutants under abiotic or biotic stress conditions.

DOI： 10.1270/jsbbs.19049

PubMed

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記述言語：英語   掲載種別：研究論文（学術雑誌）  

Dart1-24, one of the 37 autonomous DNA transposon Dart1s, was heritably activated by the demethylation of the 5' region following 5-azaC treatment of rice seeds. Transposons are controlled by epigenetic regulations. To obtain newly activated autonomous elements of Dart1, a DNA transposon, in rice, seeds of a stable pale yellow leaf (pyl-stb) mutant caused by the insertion of nDart1-0, a nonautonomous element in OsClpP5, were treated with 5-azaC, a demethylating agent. In the 5-azaC-treated M1 plants, 60-70% of the plants displayed variegated pale yellow leaf (pyl-v) phenotype, depending on the concentration of 5-azaC used, suggesting that inactivated Dart1 might become highly activated by 5-azaC treatment and nDart1-0 was excised from OsClpP5 by the activated Dart1s. Although the M2 plants derived from most of these pyl-v plants showed stable pyl phenotypes, some variegated M1 plants generated pyl-v M2 progeny. These results indicated that most M1 pyl-v phenotypes at M1 were not heritable. Dart1-24, 1-27 and 1-28 were expressed in the M2 pyl-v plants, and mapping analysis confirmed that Dart1-24 was newly activated. Further, the transgenerational activation of Dart1-24 was demonstrated to be caused by the demethylation of nucleotides in its 5' region.

DOI： 10.1007/s00122-019-03429-7

PubMed

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