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Open Access Highly Accessed Research article

Grain protein content variation and its association analysis in barley

Shengguan Cai1, Gang Yu2, Xianhong Chen1, Yechang Huang1, Xiaogang Jiang3, Guoping Zhang1 and Xiaoli Jin1*

Author Affiliations

1 Agronomy Department, Key Laboratory of Crop Germplasm Resource of Zhejiang Province, Zhejiang University, Hangzhou 310058, China

2 Department of Nuclear Medicine, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou 310009, China

3 Department of Life Science, Wenzhou Medical College, Wenzhou 325025, China

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BMC Plant Biology 2013, 13:35  doi:10.1186/1471-2229-13-35

Published: 3 March 2013



Grain protein content (GPC) is an important quality determinant for barley used as malt, feed as well as food. It is controlled by a complex genetic system. GPC differs greatly among barley genotypes and is also variable across different environments. It is imperative to understand the genetic control of barley GPC and identify the genotypes with less variation under the different environments.


In this study, 59 cultivated and 99 Tibetan wild barley genotypes were used for a genome-wide association study (GWAS) and a multi-platform candidate gene-based association analysis, in order to identify the molecular markers associated with GPC. Tibetan wild barley had higher GPC than cultivated barley. The significant correlation between GPC and diastatic power (DP), and malt extract confirmed the importance of GPC in determining malt quality. Diversity arrays technology (DArT) markers associated with barley GPC were detected by GWAS. In addition, GWAS revealed two HvNAM genes as the candidate genes controlling GPC. No association was detected between HvNAM1 polymorphism and GPC, while a single nucleotide polymorphism (SNP) (798, Pā€‰<ā€‰0.01), located within the second intron of HvNAM2, was associated with GPC. There was a significant correlation between haplotypes of HvNAM1, HvNAM2 and GPC in barley.


The GWAS and candidate gene based-association study may be effectively used to determine the genetic variation of GPC in barley. The DArT markers and the polymorphism of HvNAM genes identified in this study are useful in developing high quality barley cultivars in the future. HvNAM genes could play a role in controlling barley GPC.

Grain protein content; Malt quality; Molecular polymorphism; Tibetan wild barley (Hordeum spontaneum L.); Association mapping