Drought-Tolerance Gene Identification Using Genome Comparison and Co-Expression Network Analysis of Chromosome Substitution Lines in Rice.

Chutarat Punchkhon,Lukáš Spíchal,Supachitra Chadchawan,Teerapong Buaboocha,Theerayut Toojinda,Jonaliza L. Siangliw,Kitiporn Plaimas,Luca Comai,Nuria De Diego

doi:10.3390/genes11101197

Abstract

Drought stress limits plant growth and productivity. It triggers many responses by inducing changes in plant morphology and physiology. KDML105 rice is a key rice variety in Thailand and is normally grown in the northeastern part of the country. The chromosome segment substitution lines (CSSLs) were developed by transferring putative drought tolerance loci (QTLs) on chromosome 1, 3, 4, 8, or 9 into the KDML105 rice genome. CSSL104 is a drought-tolerant line with higher net photosynthesis and leaf water potential than KDML105 rice. The analysis of CSSL104 gene regulation identified the loci associated with these traits via gene co-expression network analysis. Most of the predicted genes are involved in the photosynthesis process. These genes are also conserved in Arabidopsis thaliana. Seven genes encoding chloroplast proteins were selected for further analysis through characterization of Arabidopsis tagged mutants. The response of these mutants to drought stress was analyzed daily for seven days after treatment by scoring green tissue areas via the PlantScreen™ XYZ system. Mutation of these genes affected green areas of the plant and stability index under drought stress, suggesting their involvement in drought tolerance.

Highlights

Rice (Oryza sativa L.) is one of the important cereal crops of the world [1]
Selected chromosome segment substitution lines (CSSLs), namely CSSL97, CSSL104, CSSL106, and CSSL107, were evaluated for drought tolerance by growing the seedlings in soil with 100% or 50% field capacity
The highest leaf-death score was detected in CSSL106, while CSSL97 had the lowest photosystem II (PSII) efficiency under drought stress

Summary

Introduction

In Thailand, rice is the major agricultural export, especially Khao Dawk Mali 105 (KDML105) rice. KDML105 rice is normally grown in the northeast of Thailand, based on rain with limited irrigation [3]. It is always affected by drought stress, leading to the reduction in growth and yield. Drought stress affects plant morphology, physiology, and molecular mechanisms. Cell turgor pressure is decreased due to low water potential in cells. This causes a decrease in the relative water content, leaf water potential, stomatal conductance, and transpiration rate [4]

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Results

Discussion

Conclusion