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Hu H.,Sichuan Agricultural University | Wang J.,Sichuan Agricultural University | Shi C.,Sichuan Agricultural University | Yuan C.,Sichuan Agricultural University | And 10 more authors.

Background: Leucine-rich repeat receptor-like kinases (LRR-RLKs) represent a large class of proteins in regulating plant development and immunity. The LRR-RLK XA21 confers resistance to the bacterial disease caused by the pathogen of Xanthomonas oryzae pv. oryzae (Xoo). Several XA21 binding proteins have been characterized, however the early events governing XA21 signaling have not been fully elucidated. Results: Here we report the identification of one LRR-RLK gene (XIK1) whose expression is induced rapidly upon the infection with the pathogen of Xoo. Expression pattern analysis reveals that XIK1 is preferentially expressed in reproductive leaves and panicles, and that expression is associated with plant development. By using RNA interference (RNAi), we silenced the expression of XIK1 in rice with Xa21 and found that reduced expression of XIK1 compromised disease resistance mediated by XA21. In addition, we found that the expression of the downstream marker genes of pathogen associated molecular pattern (PAMP) triggered immunity (PTI) in rice was compromised in Xa21 plants silenced for XIK1. Conclusion: Our study reveals that the LRR-RLK gene XIK1 is Xoo-responsive and positively regulates Xa21-mediated disease resistance. © 2014, Hu et al.; licensee Springer. Source

Wang J.,Sichuan Agricultural University | Wu G.,Sichuan Agricultural University | Peng C.,Sichuan Agricultural University | Zhou X.,Sichuan Agricultural University | And 14 more authors.
Plant Molecular Biology Reporter

Receptor-like cytoplasmic kinases (RLCKs) belong to a large subgroup of kinases that play pivotal roles in plant development and in protecting plants from various stresses. Here, we report the isolation and characterization of rice OsRLCK102, from the OsRLCK VII subgroup. Silencing of OsRLCK102 compromised receptor kinase XA21-mediated resistance to Xanthomonas oryzae pv. oryzae (Xoo) but did not affect plant basal resistance to Xoo or Magnaporthe oryzae (M. oryzae). Plants with silenced OsRLCK102 exhibit architecture alterations, including reduced plant height, enlarged angle of the lamina joint, decreased rates of seed setting and enhanced sensitivity to hormone brassinolide (BR). Collectively, our study reveals that OsRLCK102 positively regulates XA21-mediated immunity and negatively regulates rice development through BR signaling in rice. © 2015 Springer Science+Business Media New York Source

Wang J.,Sichuan Agricultural University | Ye B.,Sichuan Agricultural University | Yin J.,Sichuan Agricultural University | Yuan C.,Sichuan Agricultural University | And 12 more authors.
Plant Physiology and Biochemistry

Plants that spontaneously produce lesion mimics or spots, without any signs of obvious adversity, such as pesticide and mechanical damage, or pathogen infection, are so-called lesion mimic mutants (lmms). In rice, many lmms exhibit enhanced resistance to pathogens, which provides a unique opportunity to uncover the molecular mechanism underlying lmms. We isolated a rice light-dependent leaf lesion mimic mutant 1 (llm1). Lesion spots appeared in the leaves of the llm1 mutant at the tillering stage. Furthermore, the mutant llm1 had similar agronomic traits to wild type rice. Trypan blue and diamiobenzidine staining analyses revealed that the lesion spot formation on the llm1 mutant was due to programmed cell death and reactive oxygen species. The chloroplasts were severely damaged in the llm1 mutant, suggesting that chloroplast damage was associated with the formation of lesion spots in llm1. More importantly, llm1 exhibited enhanced resistance to bacterial blight pathogens within increased expression of pathogenesis related genes (PRs). Using a map-based cloning approach, we delimited the LLM1 locus to a 121-kb interval between two simple sequence repeat markers, RM17470 and RM17473, on chromosome 4. We sequenced the candidate genes on the interval and found that a base mutation had substituted adenine phosphate for thymine in the last exon of LOC_Os04g52130, which led to an amino acid change (Asp388 to Val) in the llm1 mutant. Our investigation showed that the putative coproporphyrinogen III oxidase (CPOX) encoded by LOC_Os04g52130 was produced by LLM1 and that amino acid Asp388 was essential for CPOX function. Our study provides the basis for further investigations into the mechanism underlying lesion mimic initiation associated with LLM1. © 2015 Elsevier Masson SAS. Source

Li W.,Sichuan Agricultural University | Liu Y.,Sichuan Agricultural University | Wang J.,Sichuan Agricultural University | He M.,Sichuan Agricultural University | And 15 more authors.
Molecular Plant Pathology

Rice blast caused by the fungal pathogen Magnaporthe oryzae is one of the most destructive diseases worldwide. Although the rice-M.oryzae interaction has been studied extensively, the early molecular events that occur in rice before full maturation of the appressorium during M.oryzae invasion are unknown. Here, we report a comparative transcriptomics analysis of the durably resistant rice variety Digu and the susceptible rice variety Lijiangxintuanheigu (LTH) in response to infection by M.oryzae (5, 10 and 20h post-inoculation, prior to full development of the appressorium). We found that the transcriptional responses differed significantly between these two rice varieties. Gene ontology and pathway analyses revealed that many biological processes, including extracellular recognition and biosynthesis of antioxidants, terpenes and hormones, were specifically activated in Digu shortly after infection. Forty-eight genes encoding receptor kinases (RKs) were significantly differentially regulated by M.oryzae infection in Digu. One of these genes, LOC_Os08g10300, encoding a leucine-rich repeat RK from the LRR VIII-2 subfamily, conferred enhanced resistance to M.oryzae when overexpressed in rice. Our study reveals that a multitude of molecular events occur in the durably resistant rice Digu before the full maturation of the appressorium after M.oryzae infection and that membrane-associated RKs play important roles in the early response. © 2016 BSPP and John Wiley & Sons Ltd. Source

Zhu X.,Sichuan Agricultural University | Zhu X.,Collaborative Innovation Center for Hybrid Rice in Yangtze River Basin at Sichuan | Liang S.,Sichuan Agricultural University | Liang S.,Collaborative Innovation Center for Hybrid Rice in Yangtze River Basin at Sichuan | And 22 more authors.

DnaJ proteins belong to chaperones of Hsp40 family that ubiquitously participate in various cellular processes. Previous studies have shown chloroplast-targeted DnaJs are involved in the development of chloroplast in some plant species. However, little is known about the function of DnaJs in rice, one of the main staple crops. In this study, we characterized a type I DnaJ protein OsDjA7/8. We found that the gene OsDjA7/8 was expressed in all collected tissues, with a priority in the vigorous growth leaf. Subcellular localization revealed that the protein OsDjA7/8 was mainly distributed in chloroplast. Reduced expression of OsDjA7/8 in rice led to albino lethal at the seedling stage. Transmission electron microscopy observation showed that the chloroplast structures were abnormally developed in the plants silenced for OsDjA7/8. In addition, the transcriptional expression of the genes tightly associated with the development of chloroplast was deeply reduced in the plants silenced for OsDjA7/8. Collectively, our study reveals that OsDjA7/8 encodes a chloroplast-localized protein and is essential for chloroplast development and differentiation in rice. © 2015 Elsevier B.V. Source

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