ADP-glucose pyrophosphorylase large subunit 2 is essential for storage substance accumulation and subunit interactions in rice endosperm.
ADP-glucose pyrophosphorylase (AGPase) controls a rate-limiting step in the starch biosynthetic pathway in higher plants. Here we isolated a shrunken rice mutant w24. Map-based cloning identified OsAGPL2, a large subunit of the cytosolic AGPase in rice endosperm, as the gene responsible for the w24 mutation. In addition to severe inhibition of starch synthesis and significant accumulation of sugar, the w24 endosperm showed obvious defects in compound granule formation and storage protein synthesis. The defect in OsAGPL2 enhanced the expression levels of the AGPase family. Meanwhile, the elevated activities of starch phosphorylase 1 and sucrose synthase in the w24 endosperm might possibly partly account for the residual starch content in the mutant seeds. Moreover, the expression of OsAGPL2 and its counterpart, OsAGPS2b, was highly coordinated in rice endosperm. Yeast two-hybrid and BiFC assays verified direct interactions between OsAGPL2 and OsAGPS2b as well as OsAGPL1 and OsAGPS1, supporting the model for spatiotemporal complex formation of AGPase isoforms in rice endosperm. Besides, our data provided no evidence for the self-binding of OsAGPS2b, implying that OsAGPS2b might not interact to form higher molecular mass aggregates in the absence of OsAGPL2. Therefore, the molecular mechanism of rice AGPase assembly might differ from that of Arabidopsis.
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Xiao-Jie
XJ
Tang
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Cheng
C
Peng
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Jie
J
Zhang
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Yue
Y
Cai
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Xiao-Man
XM
You
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Fei
F
Kong
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Hai-Gang
HG
Yan
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Guo-Xiang
GX
Wang
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Liang
L
Wang
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Jie
J
Jin
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Wei-Wei
WW
Chen
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Xin-Gang
XG
Chen
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Jing
J
Ma
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Peng
P
Wang
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China.
Ling
L
Jiang
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China. Electronic address: zhangww@njau.edu.cn.
Wen-Wei
WW
Zhang
State Key Laboratory for Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing 210095, China; Institute of Crop Science, The National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 Zhongguancun South Street, Beijing 100081, China. Electronic address: wanjm@njau.edu.cn.
Jian-Min
JM
Wan
D002874:Chromosome Mapping; D003001:Cloning, Molecular; D056625:Endosperm / Q000378:metabolism; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012275:Oryza / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013213:Starch / Q000378:metabolism
D010940:Plant Proteins; D013213:Starch; D051599:Glucose-1-Phosphate Adenylyltransferase
AGPase; Interaction; OsAGPL2; Starch synthesis