Morphological Analysis, Protein Profiling and Expression Analysis of Auxin Homeostasis Genes of Roots of Two Contrasting Cultivars of Rice Provide Inputs on Mechanisms Involved in Rice Adaptation towards Salinity Stress

Shivani Saini,Navdeep Kaur,Varinder Singh,Pascal Gantet,Baldev Singh,Pratap Kumar Pati,Deeksha Marothia

doi:10.3390/plants10081544

Abstract

Plants remodel their root architecture in response to a salinity stress stimulus. This process is regulated by an array of factors including phytohormones, particularly auxin. In the present study, in order to better understand the mechanisms involved in salinity stress adaptation in rice, we compared two contrasting rice cultivars—Luna Suvarna, a salt tolerant, and IR64, a salt sensitive cultivar. Phenotypic investigations suggested that Luna Suvarna in comparison with IR64 presented stress adaptive root traits which correlated with a higher accumulation of auxin in its roots. The expression level investigation of auxin signaling pathway genes revealed an increase in several auxin homeostasis genes transcript levels in Luna Suvarna compared with IR64 under salinity stress. Furthermore, protein profiling showed 18 proteins that were differentially regulated between the roots of two cultivars, and some of them were salinity stress responsive proteins found exclusively in the proteome of Luna Suvarna roots, revealing the critical role of these proteins in imparting salinity stress tolerance. This included proteins related to the salt overly sensitive pathway, root growth, the reactive oxygen species scavenging system, and abscisic acid activation. Taken together, our results highlight that Luna Suvarna involves a combination of morphological and molecular traits of the root system that could prime the plant to better tolerate salinity stress.

Highlights

The plant root is the vital organ that serves a wide range of functions and regulates crop productivity
Our results showed that salt tolerant rice cultivar Luna Suvarna (LS) has better stress adaptive root traits, elevated expression of auxin homeostasis genes and more endogenous indole-3-acetic acid (IAA) content than IR64 cultivar, which could be linked to the acquisition of natural salinity stress tolerance in LS
The present study shows that salt tolerant rice cultivars present salinity stress adaptive root traits, likely due to an elevated endogenous auxin content and augmented levels of key salinity stress providing proteins in its roots

Summary

Introduction

The plant root is the vital organ that serves a wide range of functions and regulates crop productivity. As roots are in direct interface with the soil, they act as the primary site for perceiving environmental stress-related signals for plants [1,2]. Salinity has emerged as one of the most serious threats limiting global crop production and yield [3]. High soil salinity induces undesirable changes at phenotypic, biochemical, physiological, cellular, genetic and molecular levels, which are detrimental to plant growth and survival [8]. The root system responds to abiotic stresses by triggering stress adaptive mechanisms, which are supposed to be regulated by a number of factors [2,9,10]

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Results

Discussion

Conclusion