Transcriptome Analysis of Drought-Resistant and Drought-Sensitive Sorghum (Sorghum bicolor) Genotypes in Response to PEG-Induced Drought Stress.

Salah E Abdel-Ghany,Asa Ben-Hur,Fahad Ullah,Anireddy S N Reddy

doi:10.3390/ijms21030772

Salah E Abdel-Ghany, Asa Ben-Hur + Show 2 more

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https://doi.org/10.3390/ijms21030772

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Abstract

Drought is a major limiting factor of crop yields. In response to drought, plants reprogram their gene expression, which ultimately regulates a multitude of biochemical and physiological processes. The timing of this reprogramming and the nature of the drought-regulated genes in different genotypes are thought to confer differential tolerance to drought stress. Sorghum is a highly drought-tolerant crop and has been increasingly used as a model cereal to identify genes that confer tolerance. Also, there is considerable natural variation in resistance to drought in different sorghum genotypes. Here, we evaluated drought resistance in four genotypes to polyethylene glycol (PEG)-induced drought stress at the seedling stage and performed transcriptome analysis in seedlings of sorghum genotypes that are either drought-resistant or drought-sensitive to identify drought-regulated changes in gene expression that are unique to drought-resistant genotypes of sorghum. Our analysis revealed that about 180 genes are differentially regulated in response to drought stress only in drought-resistant genotypes and most of these (over 70%) are up-regulated in response to drought. Among these, about 70 genes are novel with no known function and the remaining are transcription factors, signaling and stress-related proteins implicated in drought tolerance in other crops. This study revealed a set of drought-regulated genes, including many genes encoding uncharacterized proteins that are associated with drought tolerance at the seedling stage.

Highlights

Drought is one of the most important abiotic stresses that adversely affects plant growth and productivity
To screen for drought resistance at the seedling stage the root length of seven sorghum genotypes was evaluated in the presence and absence of 20% polyethylene glycol (PEG), which has been extensively used to induce water deficit in plants in a controlled manner [4,33,34,35]
Genotypes DS1 and DS2 showed the most reduction in root length (88% and 70%, respectively) compared to seedlings grown under control conditions (Figure 1b)

Summary

Introduction

Drought is one of the most important abiotic stresses that adversely affects plant growth and productivity (reviewed in [1]). It is the most common cause of food shortage in many countries [2] where it has caused over $29 billion in losses between 2005 and 2015 [3]. To cope with drought stress, plants reprogram a wide range of responses at the molecular, biochemical and physiological levels [5]. These changes often occur rapidly and with specificity based on the tissue type, developmental stage, and stress condition. Previous studies have shown that the expression of most studied dehydration-responsive element binding (DREB) proteins is low or very low in the absence of stress and is induced moderately under stress and in some cases such as AtDREB2A the activity is enhanced further by stress-induced post-translational activation [10,12]

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