Functional inactivation of UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1) induces early leaf senescence and defence responses in rice.
Plant leaf senescence and defence responses are important biological processes, but the molecular mechanisms involved are not well understood. This study identified a new rice mutant, spotted leaf 29 (spl29). The SPL29 gene was identified by map-based cloning, and SPL29 was confirmed as UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1) by enzymatic analysis. The mutant spl29 lacks UAP activity. The biological phenotypes for which UAP is responsible have not previously been reported in plants. The spl29 mutant displayed early leaf senescence, confirmed by chlorophyll loss and photosystem II decline as physiological indicators, chloroplast degradation as a cellular characteristic, and both upregulation of senescence transcription factors and senescence-associated genes, and downregulation of photosynthesis-related genes, as molecular evidence. Defence responses were induced in the spl29 mutant, shown by enhanced resistance to bacterial blight inoculation and upregulation of defence response genes. Reactive oxygen species, including O2 (-) and H2O2, accumulated in spl29 plants; there was also increased malondialdehyde content. Enhanced superoxide dismutase activity combined with normal catalase activity in spl29 could be responsible for H2O2 accumulation. The plant hormones jasmonic acid and abscisic acid also accumulated in spl29 plants. ROS and plant hormones probably play important roles in early leaf senescence and defence responses in the spl29 mutant. Based on these findings, it is suggested that UAP1 is involved in regulating leaf senescence and defence responses in rice.
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Zhaohai
Z
Wang
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Ya
Y
Wang
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Xiao
X
Hong
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Daoheng
D
Hu
Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
Caixiang
C
Liu
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Jing
J
Yang
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Yang
Y
Li
Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Hubei, 430072, China.
Yunqing
Y
Huang
Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Hubei, 430072, China.
Yuqi
Y
Feng
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Hanyu
H
Gong
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Yang
Y
Li
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China.
Gen
G
Fang
Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Centre for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China State Key Laboratory of Genetic Engineering, Metabolomics Laboratory, School of Life Sciences, Fudan University, Shanghai 200433, China.
Huiru
H
Tang
State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Hubei 430072, China lysh2001@whu.edu.cn.
Yangsheng
Y
Li
D009154:Mutation; D009713:Nucleotidyltransferases / Q000235:genetics* / Q000378:metabolism; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D010802:Phylogeny; D057865:Plant Immunity; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism
D010940:Plant Proteins; D009713:Nucleotidyltransferases; C023226:UDPacetylglucosamine pyrophosphorylase
Defence responses; SPL29; UDP-N-acetylglucosamine pyrophosphorylase 1 (UAP1).; leaf senescence; reactive oxygen species (ROS); rice (Oryza sativa)