Wei Zhou, Xin Wang, Dan Zhou, Yidan Ouyang, Jialing Yao

Summary

Increasing grain yield and improving grain quality are two important goals for rice breeding. A better understanding of the factors that contribute to the overall grain quantity and nutritional quality of rice will lay the foundation for developing new breeding strategies. RAG2 is a member of 14-to-16-kDa α-amylase/trypsin inhibitors in rice, which belong to the albumin of seed storage proteins. We found that RAG2 was specifically expressed in ripening seed and its transcription peak was between 14 and 21 days after flowering. Grain size and 1000-grain weight were obviously increased in RAG2-overexpressed lines compared with wild type, and grain size was reduced in RAG2-suppressed lines. In addition, the major storage substances of the seeds differed significantly in RAG2-overexpressed and RAG2-suppressed lines compared to wild type. The protein content and amount of total lipids were increased and decreased, respectively, in the seeds of RAG2-overexpressed and RAG2-suppressed lines. Overexpression of RAG2 significantly increased grain size and improved grain quality and yield simultaneously. These results imply that RAG2 might play an important role in regulating grain weight and seed quality of rice. The functional characterization of rice RAG2 facilitates a further understanding of the mechanisms involved in grain size and seed quality and may be helpful in improving grain yield and quantity in cereal crops.

See: http://onlinelibrary.wiley.com/doi/10.1111/pbi.12654/full

PLANT BIOTECHNOLOGY JOURNAL, 22 November 2016, DOI: 10.1111/pbi.12654

Figure 1: Structural and sequence analysis of RAG2. (a) A schematic representation of the exon and intron organization of RAG2. RAG2 consists of one exon (black box) with an 82-bp 5′UTR (grey box) and a 200-bp 3′UTR (grey box). Two ATGCAAAA (triangle, −1028 bp, −252 bp) and one CTTTAGTCTT (pentagon, −21 bp) cis-element in RAG2 promoter region. (b) Protein sequence alignment of RAG2 with RAG1, LOC_Os07g11510, LOC_Os07g11410, LOC_Os07g11330 and Bradi1g54000. Residues marked with asterisks and dots are highly conserved and semiconserved, respectively. A dash ‘–’ denotes a gap in the alignment.