Tissue Metabolic Responses to Salt Stress in Wild and Cultivated Barley

Dezhi Wu,Lingzhen Ye,Mingxian Chen,Guoping Zhang,Shengguan Cai,Haitao Zhang,Feibo Wu,Fei Dai,Zhonghua Chen,Mingliang Xu

doi:10.1371/journal.pone.0055431

Abstract

A thorough understanding of the mechanisms underlying barley salt tolerance and exploitation of elite genetic resource are essential for utilizing wild barley germplasm in developing barley varieties with salt tolerance. In order to reveal the physiological and molecular difference in salt tolerance between Tibetan wild barley (Hordeum spontaneum) and cultivated barley (Hordeum vulgare), profiles of 82 key metabolites were studies in wild and cultivated barley in response to salinity. According to shoot dry biomass under salt stress, XZ16 is a fast growing and salt tolerant wild barley. The results of metabolite profiling analysis suggested osmotic adjustment was a basic mechanism, and polyols played important roles in developing salt tolerance only in roots, and high level of sugars and energy in roots and active photosynthesis in leaves were important for barley to develop salt tolerance. The metabolites involved in tolerance enhancement differed between roots and shoots, and also between genotypes. Tibetan wild barley, XZ16 had higher chlorophyll content and higher contents of compatible solutes than CM72, while the cultivated barley, CM72 probably enhanced its salt tolerance mainly through increasing glycolysis and energy consumption, when the plants were exposed to high salinity. The current research extends our understanding of the mechanisms involved in barley salt tolerance and provides possible utilization of Tibetan wild barley in developing barley cultivars with salt tolerance.

Highlights

Nearly 20% of arable land and 50% of irrigated land in the world are salt-affected, which causes a great threat to agricultural production [1,2]
Exposed to moderate salinity for 35 days, CM72 and XZ16 did not show significant difference in shoot dry weight (SDW) compared to their controls, while Gairdner and XZ169 deceased by 19.4% and 24.1% in SDW, respectively (Fig. 1B)
The current results showed that CM72 and XZ16 were more salt-tolerant than Gairdner and XZ169

Summary

Introduction

Nearly 20% of arable land and 50% of irrigated land in the world are salt-affected, which causes a great threat to agricultural production [1,2]. The progress in developing salt-tolerant crops is significantly hampered by the physiological and genetic complexity of this trait. Barley (Hordeum vulgare L.) is a most salt tolerant crop in the grass family [3], and is widely used in physiological and genetic studies of salt tolerance. Wild barley has adapted to a broad range of environments and formed rich genetic diversities for salt tolerance [4]. Tibetan wild barley (Hordeum Spontaneum L.), considered as one of the ancestors of cultivated barley [5,6], is characterized by wide variation of abiotic tolerance, and some accessions with high tolerance to drought [7], aluminum toxicity [8] and salinity [9] have been identified. We assessed the salt tolerance of around 200 accessions of Tibetan wild barley and identified some elite salt-tolerant accessions (e.g. XZ16 and XZ26) [9,10]

Objectives

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Results

Conclusion