RESUMEN
The phytohormones, jasmonates (JAs), mediate many plant developmental processes and their responses to important environmental stresses, such as herbivore attack. Bioactive JAs are perceived by CORONATINE INSENSITIVE (COI)-receptors, and associated JAZ proteins, to activate downstream responses. To date, the JA receptors of the important monocot crop plant, rice, remain to be explored. Here, we studied all three rice COI proteins, OsCOI1a, OsCOI1b, and OsCOI2, by ligand binding, genome editing, and phenotyping and examining some of the responsible mechanisms for the different responses. OsCOI2 binds to most individual OsJAZs in the presence of endogenous JA ligands, as OsCOI1a /1b do, albeit with greater partner selectivity. Single mutants of each OsCOI and OsCOI1a/1b double mutants were constructed by CRIPSR-Cas9-based genome editing and used to phenotype developmental and defense responses. OsCOI1b is involved in root growth and grain-size control and plays overlapping roles with OsCOI1a in spikelet development, while OsCOI2 regulates leaf senescence, male sterility, root growth, and grain size. All OsCOIs mediated resistance to the devastating rice pest, the brown planthopper. However, the defense sectors regulated by OsCOI1a/1b and OsCOI2 clearly differed. Our results revealed that all three OsCOIs are functional JA receptors that play diverse roles in regulating downstream JA responses.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Oryza , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Oryza/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Plantas/metabolismo , Ciclopentanos/metabolismo , Oxilipinas/metabolismo , Regulación de la Expresión Génica de las PlantasRESUMEN
KEY MESSAGE: Jasmonate-induced accumulation of anti-herbivore compounds mediates rice resistance to the leaf folder Cnaphalocrocis medinalis. The rice leaf folder (LF), Cnaphalocrocis medinalis, is one of the most destructive insect pests in the paddy field. LF larvae induces leaf folding and scrapes the upper epidermis and mesophyll tissues reducing photosynthesis and yield in rice. Identifying plant defense pathways and genes involved in LF resistance is essential to understand better this plant-insect interaction and develop new control strategies for this pest. Jasmonate (JA) signaling controls a plethora of plant defenses against herbivores. Using RNA-seq time series analysis, we characterized changes in the transcriptome of wild-type (WT) leaves in response to LF damage and measured the dynamics of accumulation of JA phytohormone pools in time-course experiments. Genes related to JA signaling and responses, known to mediate resistance responses to herbivores, were induced by LF and were accompanied by an increment in the levels of JA pools in damaged leaves. The accumulation of defense compounds such as phenolamides and trypsin proteinase inhibitor (TPI) also increased after LF infestation in WT but not in JA mutant plants impaired in JA biosynthesis (aoc-2) and signaling (myc2-5). Consistent with all these responses, we found that LF larvae performed better in the JA mutant backgrounds than in the WT plants. Our results show that JA signaling regulates LF-induced accumulation of TPI and phenolamides and that these compounds are likely an essential part of the defense arsenal of rice plants against this insect pest.