title: Chalk5 encodes a vacuolar H(+)-translocating pyrophosphatase influencing grain chalkiness in rice.
abstract: Grain chalkiness is a highly undesirable quality trait in the marketing and consumption of rice grain. However, the molecular basis of this trait is poorly understood. Here we show that a major quantitative trait locus (QTL), Chalk5, influences grain chalkiness, which also affects head rice yield and many other quality traits. Chalk5 encodes a vacuolar H(+)-translocating pyrophosphatase (V-PPase) with inorganic pyrophosphate (PPi) hydrolysis and H(+)-translocation activity. Elevated expression of Chalk5 increases the chalkiness of the endosperm, putatively by disturbing the pH homeostasis of the endomembrane trafficking system in developing seeds, which affects the biogenesis of protein bodies and is coupled with a great increase in small vesicle-like structures, thus forming air spaces among endosperm storage substances and resulting in chalky grain. Our results indicate that two consensus nucleotide polymorphisms in the Chalk5 promoter in rice varieties might partly account for the differences in Chalk5 mRNA levels that contribute to natural variation in grain chalkiness.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Yibo
authors.initials: Y
authors.lastname: Li
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Chuchuan
authors.initials: C
authors.lastname: Fan
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Xing
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Yun
authors.affiliation: Shanghai Agrobiological Gene Center, Shanghai, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Luo
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Bao
authors.initials: B
authors.lastname: Yan
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Peng
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Weibo
authors.initials: W
authors.lastname: Xie
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Gongwei
authors.initials: G
authors.lastname: Wang
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Xianghua
authors.initials: X
authors.lastname: Li
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Xiao
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Caiguo
authors.initials: C
authors.lastname: Xu
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: He
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D056625:Endosperm / Q000737:chemistry* / Q000235:genetics / Q000648:ultrastructure; D040461:Gene Components; D006868:Hydrolysis; D043564:Inorganic Pyrophosphatase / Q000235:genetics* / Q000378:metabolism; D008156:Luciferases; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010641:Phenotype; D040641:Quantitative Trait Loci / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000166:cytology* / Q000648:ultrastructure; D017422:Sequence Analysis, DNA
chemical_list: D008156:Luciferases; D043564:Inorganic Pyrophosphatase