Elicitor-Induced Biochemical and Molecular Manifestations to Improve Drought Tolerance in Rice (Oryza sativa L.) through Seed-Priming.

Mahesh K Samota,Aruna Tyagi,Monika Awana,Archana Singh,Om P Yadav,Suresh Kumar,S V Amitha Mithra,Minnu Sasi

doi:10.3389/fpls.2017.00934

Abstract

Rice (Oryza sativa L.) is one of the major grain cereals of the Indian subcontinent which face water-deficit stress for their cultivation. Seed-priming has been reported to be a useful approach to complement stress responses in plants. In the present study, seed-priming with hormonal or chemical elicitor [viz. methyl jasmonate (MJ), salicylic acid (SA), paclobutrazol (PB)] showed significant increase in total phenolic content, antioxidant activity and expression of Rice Drought-responsive (RD1 and RD2) genes (of AP2/ERF family) in contrasting rice genotypes (Nagina-22, drought-tolerant and Pusa Sugandh-5, drought-sensitive) under drought stress. However, decrease in lipid peroxidation and protein oxidation was observed not only under the stress but also under control condition in the plants raised from primed seeds. Expression analyses of RD1 and RD2 genes showed upregulated expression in the plants raised from primed seeds under drought stress. Moreover, the RD2 gene and the drought-sensitive genotype showed better response than that of the RD1 gene and the drought-tolerant genotype in combating the effects of drought stress. Among the elicitors, MJ was found to be the most effective for seed-priming, followed by PB and SA. Growth and development of the plants raised from primed seeds were found to be better under control and drought stress conditions compared to that of the plants raised from unprimed seeds under the stress. The present study suggests that seed-priming could be one of the useful approaches to be explored toward the development of simple, cost-effective and farmer-friendly technology to enhance rice yield in rainfed areas.

Highlights

Rice (Oryza sativa L.) a drought-sensitive crop exhibits impeded growth and development when exposed to water-deficit stress at critical growth stages feeds more than three billion people and provides 50–80% of the daily calories intake (Khush, 2005)
Physiological health of the plants raised from unprimed seeds of drought-tolerant (N-22) and drought-sensitive (PS-5) genotypes under control as well as drought stress condition was found to be poorer compared to that of the plants raised from the seeds primed with any of the elicitor (Figure 1)
Our findings confirmed that Relative water content (RWC), Total phenolics content (TPC), LP, protein oxidation (PO) and AO activity are important biochemical markers of drought stress tolerance in plants

Summary

Introduction

Rice (Oryza sativa L.) a drought-sensitive crop exhibits impeded growth and development when exposed to water-deficit stress at critical growth stages feeds more than three billion people and provides 50–80% of the daily calories intake (Khush, 2005). Seed-priming affects biochemical and physiological processes (synthesis of nucleic acids and proteins, DNA repair, antioxidant activity and energy metabolism) leading to higher stress tolerance ability in the seedlings (Varierf et al, 2010; Hasanuzzaman and Fujita, 2011; Hussain et al, 2016b). Seedpriming has been demonstrated to enhance abiotic stresses tolerance, including drought, salinity, chilling and heavy metals, in different plant species (Ashraf and Rauf, 2001; Farooq et al, 2008; Bayat and Sepehri, 2012; Khan et al, 2012; Hussain et al, 2016a). The biochemical, physiological and molecular basis of seed-priming to mitigate abiotic stresses in plants is becoming clear day-byday

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