Comparative Transcriptome Analysis of Two Aegilops tauschii with Contrasting Drought Tolerance by RNA-Seq.

Xinpeng Zhao,Dale Zhang,Jiahui Li,Yumeng Zhu,Suoping Li,Shenglong Bai,Xue Han,Yuan Fang,Lechen Li

doi:10.3390/ijms21103595

Abstract

As the diploid progenitor of common wheat, Aegilops tauschii is considered to be a valuable resistance source to various biotic and abiotic stresses. However, little has been reported concerning the molecular mechanism of drought tolerance in Ae. tauschii. In this work, the drought tolerance of 155 Ae. tauschii accessions was firstly screened on the basis of their coleoptile lengths under simulated drought stress. Subsequently, two accessions (XJ002 and XJ098) with contrasting coleoptile lengths were selected and intensively analyzed on rate of water loss (RWL) as well as physiological characters, confirming the difference in drought tolerance at the seedling stage. Further, RNA-seq was utilized for global transcriptome profiling of the two accessions seedling leaves under drought stress conditions. A total of 6969 differentially expressed genes (DEGs) associated with drought tolerance were identified, and their functional annotations demonstrated that the stress response was mediated by pathways involving alpha-linolenic acid metabolism, starch and sucrose metabolism, peroxisome, mitogen-activated protein kinase (MAPK) signaling, carbon fixation in photosynthetic organisms, and glycerophospholipid metabolism. In addition, DEGs with obvious differences between the two accessions were intensively analyzed, indicating that the expression level of DEGs was basically in alignment with the physiological changes of Ae. tauschii under drought stress. The results not only shed fundamental light on the regulatory process of drought tolerance in Ae. tauschii, but also provide a new gene resource for improving the drought tolerance of common wheat.

Highlights

Common wheat, owing to its high yield, nutritional and processing qualities, has been one of the most widely cultivated crops worldwide, and accounts for approximately 20% of consumed calories by humans [1]
Besides differentially expressed genes (DEGs) with remarkably higher number than that reported by Mansouri under salt stresses, more specific functional annotations of DEGs participating in the response to drought stress were established in this work, including phytohormone metabolism and signaling, transcriptional regulation and lipid signaling, owing to the very recently established whole genome fine mapping of Ae. tauschii [22,23]
The results indicate that the signal transduction pathway of Abscisic acid (ABA) might not be a major factor in causing the difference in drought tolerance between XJ002 and XJ098

Summary

Introduction

Common wheat, owing to its high yield, nutritional and processing qualities, has been one of the most widely cultivated crops worldwide, and accounts for approximately 20% of consumed calories by humans [1]. Drought is one of the most prevalent abiotic stresses around the world, and causes a serious decrease in crop production and quality [4]. In this regard, the development of a wheat variety with drought tolerance is an effective approach to improving and maintaining productivity of wheat. The development of a wheat variety with drought tolerance is an effective approach to improving and maintaining productivity of wheat Limited by their narrow genetic background, it has become increasingly difficult to obtain a fine wheat variety with drought tolerance and high yield by way of hybridization among varieties. A greater tolerance to drought has been found in their wild relatives compared with domesticated descendants, which provides new genes and alleles to improve the drought tolerance and enrich the genetic background of common wheat [5]

Methods

Findings

Discussion

Conclusion