Biotic elicitor induced biochemical and molecular manifestations of drought tolerance in contrasting rice (Oryza sativa L.) genotypes

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Date
2016
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DIVISION OF BIOCHEMISTRY ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
Drought is one of the major problems of crop production in most of the countries, particularly in rice growing areas.Rice (Oryza sativa L.), is one of the major food grain cereal crops of the Indian and the world subcontinent. It belongs to the family Graminae (Poaceae) and is a model system for cereal biology because of its smaller genome size of 430 Mb,mthat spans across 12 chromosomes. It is a drought susceptible crop exhibiting deleterious effects when exposed to water stress at critical growth stages. Seed priming/treatment is one of the useful approaches to manipulate stress induced biochemical and molecular responses. Seed priming with biotic elicitors such as methyl jasmonate (MJ) salicylic acid (SA) and paclobutrazol (PBZ) showed variation in relative water content (RWC) total phenolic content (TPC), lipid peroxidation (LP), total antioxidant activity (AO), protein oxidation and expressions of genes (RD1: EF-362638 andRD2: KC-988330) from AP2/ERF transcription family in shoot region of the contrasting rice genotypes viz Nagina-22 ( N22,droughttolerant) and Pusa Sugandh-5 (PS-5,drought-susceptible). A progressive increase in TPC and AO activities, while decrease in LP, PO and RWC was observed in the primed genotypes under drought stress. MJ priming was found to increase TPC levels by 45% and 15% in the tolerant and susceptible genotypes,respectively. About 58% and 27% reduction was observed in the LP level of tolerant variety primed with MJ and PBZ respectively, while increase of 35% in AO activity was found in case of PBZ. PO levels were found to be decreased by 51% and 73% in MJ and PBZ primed drought treated plants of tolerant genotype, while 20% and 46% reduction was observed in the susceptible genotype, respectively. Both RD1 and RD2genes were found to be up-regulated under drought stress condition and RD2 gene expression washigher than the RD1 gene in all the cases. MJ treatment induced 2.9 fold and 1.8 fold up-regulation of RD1 gene in drought stressed N-22 and PS-5 genotypes, respectively. Its expression was 2.2 fold increased in PS-5 with insignificant variation in the N-22 genotype when primed with SA. RD2 gene expression was found 1.6 fold and 3.5 fold up-regulated in the tolerant and susceptible genotypes,respectively. Its expression was 5.5 fold increased in susceptible genotype with insignificant variation in the tolerant genotype with respect to SA priming. PBZ was found to induce upregulation of RD1 gene by 2.4 fold in the tolerant genotype with insignificant variationin the susceptible one. Its expression was found 1.4fold and 5 fold upregulated in the tolerant and susceptible genotypes respectively. Among the biotic elicitors,MJ was found to be the most effective priming reagent, followed by PBZ and SA to mitigate drought stress induced biochemical and molecular responses. Present findings could be explored further to mitigate drought stress in order to improve rice yield in dry land areas.
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t-9401
Keywords
Biotic elicitor induced biochemical and molecular manifestations , drought tolerance in contrasting rice (Oryza sativa L.) genotypes
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