title: Isolation and characterization of a spotted leaf 32 mutant with early leaf senescence and enhanced defense response in rice.
abstract: Leaf senescence is a complex biological process and defense responses play vital role for rice development, their molecular mechanisms, however, remain elusive in rice. We herein reported a rice mutant spotted leaf 32 (spl32) derived from a rice cultivar 9311 by radiation. The spl32 plants displayed early leaf senescence, identified by disintegration of chloroplasts as cellular evidence, dramatically decreased contents of chlorophyll, up-regulation of superoxide dismutase enzyme activity and malondialdehyde, as physiological characteristic, and both up-regulation of senescence-induced STAY GREEN gene and senescence-associated transcription factors, and down-regulation of photosynthesis-associated genes, as molecular indicators. Positional cloning revealed that SPL32 encodes a ferredoxin-dependent glutamate synthase (Fd-GOGAT). Compared to wild type, enzyme activity of GOGAT was significantly decreased, and free amino acid contents, particularly for glutamate and glutamine, were altered in spl32 leaves. Moreover, the mutant was subjected to uncontrolled oxidative stress due to over-produced reactive oxygen species and damaged scavenging pathways, in accordance with decreased photorespiration rate. Besides, the mutant showed higher resistance to Xanthomonas oryzae pv. Oryzae than its wild type, coupled with up-regulation of four pathogenesis-related marker genes. Taken together, our results highlight Fd-GOGAT is associated with the regulation of leaf senescence and defense responses in rice.
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Liting
authors.initials: L
authors.lastname: Sun
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Ling-Long
authors.initials: LL
authors.lastname: Liu
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Chunming
authors.initials: C
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Gan
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Zhengyao
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Di
authors.initials: D
authors.lastname: Wang
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Mei
authors.initials: M
authors.lastname: Niu
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Wuhua
authors.initials: W
authors.lastname: Long
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Zheng
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Jiang
authors.affiliation: State Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, China.|National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Wan
mesh_terms: D000594:Amino Acid Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008315:Malondialdehyde / Q000378:metabolism; D009154:Mutation; D012275:Oryza / Q000235:genetics* / Q000254:growth & development / Q000382:microbiology; D018384:Oxidative Stress; D057865:Plant Immunity; D018515:Plant Leaves / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D014974:Xanthomonas / Q000472:pathogenicity
chemical_list: D010940:Plant Proteins; D008315:Malondialdehyde; D013482:Superoxide Dismutase; D000594:Amino Acid Oxidoreductases; C042233:glutamate synthase (ferredoxin)