Single nucleotide polymorphisms in HSP17.8 and their association with agronomic traits in barley.

Yanshi Xia,Zhengxiang Ning,Ronghua Li,Rajeev K Varshney,Peiguo Guo,Guijun Yan,Guihua Bai,Michael Baum,Kadambot H M Siddique

doi:10.1371/journal.pone.0056816

Abstract

Small heat shock protein 17.8 (HSP17.8) is produced abundantly in plant cells under heat and other stress conditions and may play an important role in plant tolerance to stress environments. However, HSP17.8 may be differentially expressed in different accessions of a crop species exposed to identical stress conditions. The ability of different genotypes to adapt to various stress conditions resides in their genetic diversity. Allelic variations are the most common forms of genetic variation in natural populations. In this study, single nucleotide polymorphisms (SNPs) of the HSP17.8 gene were investigated across 210 barley accessions collected from 30 countries using EcoTILLING technology. Eleven SNPs including 10 from the coding region of HSP17.8 were detected, which form nine distinguishable haplotypes in the barley collection. Among the 10 SNPs in the coding region, six are missense mutations and four are synonymous nucleotide changes. Five of the six missense changes are predicted to be deleterious to HSP17.8 function. The accessions from Middle East Asia showed the higher nucleotide diversity of HSP17.8 than those from other regions and wild barley (H. spontaneum) accessions exhibited greater diversity than the cultivated barley (H. vulgare) accessions. Four SNPs in HSP17.8 were found associated with at least one of the agronomic traits evaluated except for spike length, namely number of grains per spike, thousand kernel weight, plant height, flag leaf area and leaf color. The association between SNP and these agronomic traits may provide new insight for study of the gene's potential contribution to drought tolerance of barley.

Highlights

Small heat shock proteins with a molecular weight of 15 to 42 kDa are produced ubiquitously in prokaryotic and eukaryotic cells under heat and other stress conditions at various growth stages [1,2,3,4,5]
Large phenotypic variation was observed for all traits, and significant correlations between the various phenotypic traits were found among the barley accessions (Table 2)
Nucleotide polymorphisms By using EcoTILLING, 13 polymorphic sites were detected in the targeted region of HSP17.8 across the 210 accessions (Table 3, Fig. 1)

Summary

Introduction

Small heat shock proteins (sHSPs) with a molecular weight of 15 to 42 kDa are produced ubiquitously in prokaryotic and eukaryotic cells under heat and other stress conditions at various growth stages [1,2,3,4,5]. Most sHSPs have strong cytoprotective effects by keeping functional conformations of proteins or refolding denatured proteins, relieving protein from aggregation and removing harmful polypeptides under stress conditions [6]. These sHSPs are classified into several subgroups based on DNA sequence similarity, immunological cross-reactivity and intracellular localization [7]. Several studies have postulated that HSP17.8 plays a role in tolerance to heat [8], freezing [9,10] and drought [11,12]. In the case of barley, HSP17.8 showed expression exclusively in drought-tolerant barley genotypes e.g. Martin and Hordeum spontaneum 41-1, and not in drought-sensitive genotype e.g. Moroc, under drought stress [12]

Methods

Results

Discussion

Conclusion