title: Phytochromes regulate SA and JA signaling pathways in rice and are required for developmentally controlled resistance to Magnaporthe grisea.
abstract: Old leaves of wild-type rice plants (Oryza sativa L. cv. Nipponbare) are more resistant to blast fungus (Magnaporthe grisea) than new leaves. In contrast, both old and new leaves of the rice phytochrome triple mutant (phyAphyBphyC) are susceptible to blast fungus. We demonstrate that pathogenesis-related class 1 (PR1) proteins are rapidly and strongly induced during M. grisea infection and following exogenous jasmonate (JA) or salicylic acid (SA) exposure in the old leaves, but not in the new leaves of the wild-type. In contrast, the accumulation of PR1 proteins was significantly attenuated in old and new leaves of the phyAphyBphyC mutant. These results suggest that phytochromes are required for the induction of PR1 proteins in rice. Basal transcription levels of PR1a and PR1b were substantially higher in the wild-type as compared to the phyAphyBphyC mutant, suggesting that phytochromes also are required for basal expression of PR1 genes. Moreover, the transcript levels of genes known to function in SA- or JA-dependent defense pathways were regulated by leaf age and functional phytochromes. Taken together, our findings demonstrate that phytochromes are required in rice for age-related resistance to M. grisea and may indirectly increase PR1 gene expression by regulating SA- and JA-dependent defense pathways.
authors.affiliation: High-Tech Research Center, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China. xzhxie2010@163.com
authors.forename: Xian-Zhi
authors.initials: XZ
authors.lastname: Xie
authors.forename: Yan-Jiu
authors.initials: YJ
authors.lastname: Xue
authors.forename: Jin-Jun
authors.initials: JJ
authors.lastname: Zhou
authors.forename: Bin
authors.initials: B
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Chang
authors.forename: Makoto
authors.initials: M
authors.lastname: Takano
mesh_terms: D003517:Cyclopentanes / Q000276:immunology*; D018506:Gene Expression Regulation, Plant; D020082:Magnaporthe / Q000502:physiology*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics / Q000254:growth & development* / Q000276:immunology* / Q000382:microbiology; D054883:Oxylipins / Q000276:immunology*; D010935:Plant Diseases / Q000276:immunology / Q000382:microbiology*; D010937:Plant Growth Regulators / Q000276:immunology*; D010940:Plant Proteins / Q000235:genetics / Q000276:immunology; D020156:Salicylic Acid / Q000276:immunology*; D015398:Signal Transduction
chemical_list: D003517:Cyclopentanes; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; C011006:jasmonic acid; D020156:Salicylic Acid