Functional defect at the rice choline monooxygenase locus from an unusual post-transcriptional processing is associated with the sequence elements of short-direct repeats.
Glycine betaine (GB), a quaternary ammonium solute, plays a crucial role in developing osmotic tolerance. Rice contains a choline monooxygenase (CMO) and two betaine aldehyde dehydrogenase homologues that are required for GB synthesis, but usually no GB is accumulated in rice (Oryza sativa). To elucidate the molecular processes that underlie the GB deficiency in rice, an experiment involving rice and spinach (Spinacia oleracea) was conducted to analyze the products transcribed from CMO genes. Reverse transcription-polymerase chain reaction (RT-PCR) was used to obtain CMO transcripts and a sequencing approach was employed to analyze the structural composition of various CMO transcripts. The results showed that most rice CMO transcripts were processed incorrectly, retaining introns or deleted of coding sequences; the unusual deletion events occurred at sequence elements of the short-direct repeats. In conclusion, the production of incorrect CMO transcripts results in a deficiency of the full-length CMO protein and probably reduces GB accumulation considerably in rice plants. Sequence comparison results also implied that the unusual deletion-site selection might be mediated by the short-direct repeats in response to stress conditions.
Luo
Di
D
Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, Sichuan University, Chengdu 610064, China.
Niu
Xiangli
X
Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, Sichuan University, Chengdu 610064, China.
Wang
Yuguo
Y
Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Fudan University, Shanghai 200433, China.
Zheng
Wenjing
W
Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, Sichuan University, Chengdu 610064, China.
Chang
Lijuan
L
Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, Sichuan University, Chengdu 610064, China.
Wang
Qilin
Q
Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, Sichuan University, Chengdu 610064, China.
Wei
Xin
X
Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, Sichuan University, Chengdu 610064, China.
Yu
Guirong
G
Institute of Biotechnology, Sichuan Academy of Agricultural Sciences, Chengdu 610066, China.
Lu
Bao-Rong
BR
Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, Fudan University, Shanghai 200433, China.
Liu
Yongsheng
Y
Ministry of Education Key Laboratory for Bio-resource and Eco-environment, College of Life Science, Sichuan University, Chengdu 610064, China.|State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610064, China.
D000595:Amino Acid Sequence; D001483:Base Sequence; D001622:Betaine / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics*; D017353:Gene Deletion; D018506:Gene Expression Regulation, Plant; D007438:Introns; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D010105:Oxygenases / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D018724:Spinacia oleracea
D018744:DNA, Plant; D001622:Betaine; C105448:choline monooxygenase; D010105:Oxygenases