Changes in expression of polyamines and ethylene biosynthesis genes in groundnut (Arachis hypogaea L.) genotypes during Sclerotium rolfsii infection

476-483Stem rot disease caused by fungal pathogen, Sclerotium rolfsii Sacc., is potential threat to groundnut production in warm and humid condition. After host-pathogen interaction, a multitude of plant resistance associated reactions are initiated. In the present investigation we studied the role of polyamines and ethylene during host-pathogen interaction in stem rot tolerant (CS319, GG17 and GG31) and susceptible (TG37A) groundnut genotypes at 24, 48 and 72 h after infection. Stem rot tolerant genotypes showed higher expression of polyamine biosynthesis genes ornithine decarboxylase (Ordec), spermine synthase (Sms) and lipoxygenase1 (LOX1) gene at 72 h after infection than that of susceptible genotype TG37A. The expression analysis of ethylene biosynthesis genes (1-aminocyclopropane-1-carboxylate oxidase: ACCO and (ACCS) showed up regulation in stem rot susceptible genotype TG37A than that of tolerant genotypes after infection at all stages (24, 48 and 72 h after infection). The expression of amine oxidase (AMO) gene was observed highest in stem rot susceptible genotype TG37A while minimum in GJG31. Expression of this gene was remarkably induced in TG37A which may leads to higher accumulation of H2O2. Higher content of a polyamine, putrescine was found in the leaves of stem rot tolerant genotypes at 48 and 72 h after infection. These results implied that tolerant genotypes induced higher polyamine biosynthesis which may involve in plant defense and impart tolerance/ resistance. While, susceptible genotype (TG37A), utilized higher flux of S-Adenosyl methionine (SAM) for ethylene biosynthesis which may leads to necrosis of plants. Thus, stem rot resistant genotypes may be developed through genetic manipulation of polyamine biosynthesis pathway

Not Available

Not AvailableVarious metabolites were analyzed in groundnut genotypes grown under varying temperature regimes (based on date of sowing). Four contrasting groundnut genotypes viz. ICGS44 (high-temperature tolerant), AK159 and GG7 (moderately-high-temperature tolerant), and DRG1 (high-temperature sensitive) were grown at three different temperature regimes i.e., low (early date of sowing), normal (normal date of sowing) and high temperature (late date of sowing) under field conditions. Untargeted metabolomic analysis of leaf tissue was performed by GC–MS, while targeted metabolite profiling was carried out by HPLC (polyamines) and UPLC-MS/MS (phenolics) at both the pegging and pod filling stages. Untargeted metabolomic profiling revealed exclusive expression/induction of beta-d-galactofuranoside, l-threonine, hexopyranose, d-glucopyranose, stearic acid, 4-ketoglucose, d-gulose, 2-o-glycerol-alpha-d-galactopyranoside and serine in ICGS44 during the pegging stage under high-temperature conditions. During the pod filling stage at higher temperature, alpha-d-galactoside, dodecanedioic acid, 1-nonadecene, 1-tetradecene and beta-d-galactofuranose were found to be higher in both ICGS44 and GG7. Moreover, almost all the metabolites detected by GC–MS were found to be higher in GG7, except beta-d-galactopyranoside, beta-d-glucopyranose, inositol and palmitic acid. Accumulation of putrescine was observed to be higher during low-temperature stress, while agmatine showed constitutive expression in all the genotypes, irrespective of temperature regime and crop growth stage. Interestingly, spermidine was observed only in the high-temperature tolerant genotype ICGS44. In our study, we found a higher accumulation of cinnamic acid, caffeic acid, salicylic acid and vanillic acid in ICGS44 compared to that of other genotypes at the pegging stage, whereas catechin and epicatechin were found during the pod filling stage in response to high-temperature stress, suggesting their probable roles in heat-stress tolerance in groundnut.Not Availabl