Deciphering Molecular Mechanisms Involved in Salinity Tolerance in Guar (Cyamopsis tetragonoloba (L.) Taub.) Using Transcriptome Analyses.

Biswa R. Acharya,Jorge F. S. Ferreira,Christian Dueñas,Devinder Sandhu,Kulbhushan K. Grover

doi:10.3390/plants11030291

Biswa R. Acharya, Jorge F. S. Ferreira + Show 3 more

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https://doi.org/10.3390/plants11030291

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Abstract

Guar is a commercially important legume crop known for guar gum. Guar is tolerant to various abiotic stresses, but the mechanisms involved in its salinity tolerance are not well established. This study aimed to understand molecular mechanisms of salinity tolerance in guar. RNA sequencing (RNA-Seq) was employed to study the leaf and root transcriptomes of salt-tolerant (Matador) and salt-sensitive (PI 340261) guar genotypes under control and salinity. Our analyses identified a total of 296,114 unigenes assembled from 527 million clean reads. Transcriptome analysis revealed that the gene expression differences were more pronounced between salinity treatments than between genotypes. Differentially expressed genes associated with stress-signaling pathways, transporters, chromatin remodeling, microRNA biogenesis, and translational machinery play critical roles in guar salinity tolerance. Genes associated with several transporter families that were differentially expressed during salinity included ABC, MFS, GPH, and P-ATPase. Furthermore, genes encoding transcription factors/regulators belonging to several families, including SNF2, C2H2, bHLH, C3H, and MYB were differentially expressed in response to salinity. This study revealed the importance of various biological pathways during salinity stress and identified several candidate genes that may be used to develop salt-tolerant guar genotypes that might be suitable for cultivation in marginal soils with moderate to high salinity or using degraded water.

Highlights

Soil salinization is a serious global problem as saline soil severely impacts crop productivity
To understand the molecular mechanism of salinity tolerance of guar at the transcriptome level of the salt-tolerant ‘Matador’ (‘03’, hereafter) and salt-sensitive ‘PI 340261’ (‘22’, hereafter), a three-factor RNA sequencing (RNA-Seq) experiment was performed with two levels/factors to examine differential gene expression between variables: genotypes (03 and 22), tissue types, and treatment types
A total of 296,167 transcripts (≥200 bp) were identified, with transcript sizes ranging from 200 bp to 19,633 bp, of which 46% had more than 1000 bp

Summary

Introduction

Soil salinization is a serious global problem as saline soil severely impacts crop productivity. High concentrations of NaCl in the soil cause a reduction in water potential that in turn leads to reduced availability of water from the soil to the plant, which induces osmotic stress in plants [3]. Soil ions such as Na+ and Cl− enter plants through outer root cells [4]. Increasing ions inside plant cells cause an ionic imbalance that leads to immediate osmotic stress followed by ionic toxicity and the production of reactive oxygen species. To prevent the severity of salinity-induced osmotic stress, plants synthesize various compatible solutes and osmoprotectants (betaine, glycine, inositol, mannitol, trehalose, and polyamines) [2,5,6]

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