Global analysis of gene expression profiles in physic nut (Jatropha curcas L.) seedlings exposed to salt stress.

Lin Zhang,Huawu Jiang,Meiru Li,Yaping Chen,Pingzhi Wu,Chao Zhang,Guojiang Wu,Els J M Van Damme

doi:10.1371/journal.pone.0097878

Abstract

BackgroundSalt stress interferes with plant growth and production. Plants have evolved a series of molecular and morphological adaptations to cope with this abiotic stress, and overexpression of salt response genes reportedly enhances the productivity of various crops. However, little is known about the salt responsive genes in the energy plant physic nut (Jatropha curcas L.). Thus, excavate salt responsive genes in this plant are informative in uncovering the molecular mechanisms for the salt response in physic nut.Methodology/Principal FindingsWe applied next-generation Illumina sequencing technology to analyze global gene expression profiles of physic nut plants (roots and leaves) 2 hours, 2 days and 7 days after the onset of salt stress. A total of 1,504 and 1,115 genes were significantly up and down-regulated in roots and leaves, respectively, under salt stress condition. Gene ontology (GO) analysis of physiological process revealed that, in the physic nut, many “biological processes” were affected by salt stress, particular those categories belong to “metabolic process”, such as “primary metabolism process”, “cellular metabolism process” and “macromolecule metabolism process”. The gene expression profiles indicated that the associated genes were responsible for ABA and ethylene signaling, osmotic regulation, the reactive oxygen species scavenging system and the cell structure in physic nut.Conclusions/SignificanceThe major regulated genes detected in this transcriptomic data were related to trehalose synthesis and cell wall structure modification in roots, while related to raffinose synthesis and reactive oxygen scavenger in leaves. The current study shows a comprehensive gene expression profile of physic nut under salt stress. The differential expression genes detected in this study allows the underling the salt responsive mechanism in physic nut with the aim of improving its salt resistance in the future.

Highlights

Salinity is a major abiotic stress which seriously affects plant growth and crop productivity
The current paper provides an overview of the transcriptome of physic nut plants exposed to salt stress, and this would be useful for understanding the molecular mechanisms underlying salt response in plants
Using next-generation sequencing-based digital gene expression tag profiling, we examined genome-wide changes in the transcriptomes of physic nut seedlings at 2 h, 2 d and 7 d. 17649 and 15964 protein-encoding genes with clean tags transcripts were detected in roots and leaves, respectively

Summary

Introduction

Salinity is a major abiotic stress which seriously affects plant growth and crop productivity. Plant responses to salinity are associated with osmotic regulation mechanisms [3]. There are several signal transduction pathways linked to high salinity, both ABA-dependent and ABA-independent. In the ABA-independent pathways, DREB2s (dehydration response element-binding protein 2), NAC (NAM, ATAF1/2, CUC2) and HD-ZIP (homeodomain leucine zipper protein) are important transcription factors associated with responses to dehydration and high salinity [5]. TFs NAC2 and ERF4 (ethyleneresponsive transcription factor 4) affect root structure and regulate other physiological pathways in Arabidopsis [6,7]. Plants have evolved a series of molecular and morphological adaptations to cope with this abiotic stress, and overexpression of salt response genes reportedly enhances the productivity of various crops. Excavate salt responsive genes in this plant are informative in uncovering the molecular mechanisms for the salt response in physic nut

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Results

Conclusion