OsAAP6 functions as an important regulator of grain protein content and nutritional quality in rice.

Bo Peng,Liang Sun,Wen Yao,Caiguo Xu,Xingmin Lian,Qinglu Zhang,Lingqiang Wang,Lijun Luo,Yuqing He,Guanjun Gao,Gongwei Wang,Huili Kong,Yibo Li,Yong Peng,Lei Lei,Xianghua Li,Ming Zhong,Jinghua Xiao,Junxiao Chen,Weibo Xie

doi:10.1038/ncomms5847

Abstract

Grains from cereals contribute an important source of protein to human food, and grain protein content (GPC) is an important determinant of nutritional quality in cereals. Here we show that the quantitative trait locus (QTL) qPC1 in rice controls GPC by regulating the synthesis and accumulation of glutelins, prolamins, globulins, albumins and starch. qPC1 encodes a putative amino acid transporter OsAAP6, which functions as a positive regulator of GPC in rice, such that higher expression of OsAAP6 is correlated with higher GPC. OsAAP6 greatly enhances root absorption of a range of amino acids and has effects on the distribution of various amino acids. Two common variations in the potential cis-regulatory elements of the OsAAP6 5′-untranslated region seem to be associated with GPC diversity mainly in indica cultivars. Our results represent the first step toward unravelling the mechanism of regulation underlying natural variation of GPC in rice.

Highlights

Grains from cereals contribute an important source of protein to human food, and grain protein content (GPC) is an important determinant of nutritional quality in cereals
To identify the gene(s) underlying the qPC1 quantitative trait locus (QTL) for GPC, we used 190 recombinant inbred lines (RILs) derived from a cross between Zhenshan 97 (ZS97, Oryza sativa L. ssp. indica) and Nanyangzhan (NYZ, O. sativa L. ssp. japonica). qPC1 was mapped to the interval between markers RM472 and RM104 on the long arm of chromosome 1 (Fig. 1a)
Our results revealed that OsAAP6 functions as a positive regulator of GPC and greatly enhances the total amount of amino acids

Summary

Introduction

Grains from cereals contribute an important source of protein to human food, and grain protein content (GPC) is an important determinant of nutritional quality in cereals. We show that the quantitative trait locus (QTL) qPC1 in rice controls GPC by regulating the synthesis and accumulation of glutelins, prolamins, globulins, albumins and starch. Some genes regulate starch storage and have effects on protein in the endosperm, for example, transgenic RNA interference (RNAi) targeting the Opaque[7] gene causes downregulation of GPC in both maize and rice, and the FLOURY ENDOSPERM2 gene mutant results in reduced accumulation of glutelin[12,13]. We report the cloning of the major QTL qPC1 (a putative amino acid permease, OsAAP6) controlling natural variation in GPC by a map-based cloning strategy. Complementation, RNAi and transmission electron microscopy studies that OsAAP6 functions as an important regulator of GPC and nutritional quality in rice

Methods

Results

Conclusion