Trigonella foenum-graecum (fenugreek) differentially regulates antioxidant potential, photosynthetic, and metabolic activities under arsenic stress.

Arsenic (As) contamination is continuously increasing in the groundwaters and soils around the world causing toxicity in the plants with a detrimental effect on physiology, growth, and yield. In a hydroponic system, thirty-day-old plants of Trigonella foenum-graecum were subjected to 0, 50, or 100 µM NaHAsO40.7 H2O for 10 days. The magnitude of oxidative stress increased, whereas growth indices and photosynthetic parameters decreased in a dose-dependent manner. The efficiency of photosystem II in terms of Hill reaction activity (HRA) or chlorophyll-a was adversely affected by As stress. The antioxidant potential of plants regarding ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays was enhanced, indicating the augmented resistance mechanism in plants to counter As stress. The metabolite analysis of leaf extracts revealed many As responsive metabolites including amino acids, organic acids, sugars/polyols, and others. Phenylalanine and citrulline were highly accumulated at 50 or 100 µM As, salicylic acid accumulated more at 50 µM of As while ascorbic acid notably increased at 100 µM of As. At 50 or 100 µM As, the glucose and fructose contents increased while the sucrose content decreased. At both As doses, tagatose and glucitol contents were 13 times higher than controls. Varied accumulation of metabolites could be associated with the different As doses that represent the range of tolerance in T. foenum-graecum towards As toxicity. Pathway analysis of metabolites revealed that amino acid and carbohydrate metabolism and the citrate cycle play important roles under As stress. This study helps in a better metabolomic understanding of the dose-dependent toxicity and response of As in T. foenum-graecum.

Triacontanol attenuates drought-induced oxidative stress in Brassica juncea L. by regulating lignification genes, calcium metabolism and the antioxidant system.

Effect of triacontanol on drought-induced stress was studied in Brassica juncea L. Foliage of sixteen-days-old plants was sprayed with concentrations (0, 10, 20 and 30 µM) of triacontanol (TRIA) for 7 days. Subsequently, plants were subjected to drought stress (10% polyethylene glycol, PEG6000) for 7 days. Drought stress increased oxidative stress (TBARS, O2●- and H2O2), however, their contents were reduced by TRIA. Total soluble sugars, reduced glutathione, and proline content in stressed plants were increased by TRIA. Activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT), and phenylalanine ammonia-lyase (PAL) activity were significantly increased in a dose-dependent manner with TRIA. Potassium (K+) level declined, while magnesium (Mg2+) and calcium (Ca2+) contents increased. The elevated level of lignin under drought with TRIA was significantly associated with MYB46 and PAL gene expression patterns. Altogether, our results suggest that foliar spray of 20 µM TRIA was more operative in reducing the negative impact of drought stress in B. juncea by regulating the antioxidant system, calcium, and lignification.

Comparative assessment of four RNA extraction methods and modification to obtain high-quality RNA from Parthenium hysterophorus leaf.

Isolation of high-quality RNA from weed plants such as Parthenium hysterophorus is a difficult task due to the hindrance caused by numerous secondary metabolites. Such metabolites not only affect the quality and yield of RNA, but also limit the quality of downstream applications. Therefore, the present study was undertaken to design a protocol for yielding RNA with better quality and quantity from P. hysterophorus leaf which could be suitable for functional genomics. To achieve the objective, four different important RNA extraction protocols, viz. acid guanidinium thiocyanate-phenol-chloroform, phenol-LiCl precipitation, TRIzol®, and PVP-ethanol were tested. The PVP-ethanol method proved to be best among the tested protocols. This method was further modified for obtaining improved quality and yield of RNA. The modified method successfully enhanced the yield of RNA from 280 to 334 µg g-1 fresh weight. The absorbance ratio (A260/A280) was in the purity range of 1.9 that indicated the good quality of RNA. To prove the feasibility of the extracted RNA in PCR-based cDNA synthesis, actin transcripts were targeted and successfully amplified using suitable primers. The improved protocol thus not only improved the yield and quality of RNA, but also gave better results in reverse transcriptase PCR.