Abstract
Pervasive use of chlorpyrifos (CP), an organophosphorus pesticide, has been proven to be fatal for plant growth, especially at higher concentrations. CP poisoning leads to growth inhibition, chlorosis, browning of roots and lipid and protein degradation, along with membrane dysfunction and nuclear damage. Plants form a linking bridge between the underground and above-ground communities to escape from the unfavourable conditions. Association with beneficial rhizobacteria promotes the growth and development of the plants. Plant hormones are crucial regulators of basically every aspect of plant development. The growing significance of plant hormones in mediating plant–microbe interactions in stress recovery in plants has been extensively highlighted. Hence, the goal of the current study was to investigate the effect of 24-epibrassinolide (EBL) and PGPRs (Pseudomonas aeruginosa (Ma), Burkholderia gladioli (Mb)) on growth and the antioxidative defence system of CP-stressed Brassica juncea L. seedlings. CP toxicity reduced the germination potential, hypocotyl and radicle development and vigour index, which was maximally recuperated after priming with EBL and Mb. CP-exposed seedlings showed higher levels of superoxide anion (O2−), hydrogen peroxide (H2O2), lipid peroxidation and electrolyte leakage (EL) and a lower level of nitric oxide (NO). In-vivo visualisation of CP-stressed seedlings using a light and fluorescent microscope also revealed the increase in O2−, H2O2 and lipid peroxidation, and decreased NO levels. The combination of EBL and PGPRs reduced the reactive oxygen species (ROS) and malondialdehyde (MDA) contents and improved the NO level. In CP-stressed seedlings, increased gene expression of defence enzymes such as superoxide dismutase (SOD), ascorbate peroxidase (APOX), glutathione peroxidase (GPOX), dehydroascorbate reductase (DHAR) and glutathione reductase (GPOX) was seen, with the exception of catalase (CAT) on supplementation with EBL and PGPRs. The activity of nitrate reductase (NR) was likewise shown to increase after treatment with EBL and PGPRs. The results obtained from the present study substantiate sufficient evidence regarding the positive association of EBL and PGPRs in amelioration of CP-induced oxidative stress in Brassica juncea seedlings by strengthening the antioxidative defence machinery.
Highlights
The rising demand for food for the exponentially growing population of the world, which is projected to reach the 9.8 billion mark by 2050 [1], forces the world’s agricultural systems to adapt different channels to enhance the yield [2]
Effect of EBL and PGPRs on Growth of Brassica juncea Seedlings Treated with CP
The annotations prepared on the growth profile of B. juncea to assess the effect of EBL and PGPRs under CP stress were measured in requisites of germination potential treatments
Summary
The rising demand for food for the exponentially growing population of the world, which is projected to reach the 9.8 billion mark by 2050 [1], forces the world’s agricultural systems to adapt different channels to enhance the yield [2]. Around 3.13% of the world’s total land is suitable for agriculture, and only 38.47% of that is used primarily for farming [3]. Pesticides are being used at an unprecedented rate around the world to meet the demand and to ensure the quality of vegetation. The intensive, repeated, persistent and desultory intake of diverse pesticides, on the other hand, pollutes the environment with their leftovers [4]. Pesticidal residues present in the environment eventually find a way to enter the food chain, exposing the whole ecosystem [5]
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