ABSTRACT
Soil acidity causes proton (H+) rhizotoxicity, inhibits plant growth and development, and is a major yield-limiting factor for wheat production worldwide. Therefore, we investigated the physiological and biochemical responses of wheat (Triticum aestivum L.) to acidity stress in vitro. Five popular wheat cultivars developed by Bangladesh Agricultural Research Institute (BARI), namely, BARI Gom-21, BARI Gom-24, BARI Gom-25, BARI Gom-26, and BARI Gom-30, were studied in growing media under four different pH levels (3.5, 4.5, 5.5, and 6.5). We evaluated the cultivars based on their relative water content, proline (Pro) content, growth, biomass accumulation, oxidative damage, membrane stability, and mineral composition, as well as the performance of the antioxidant defense and glyoxalase systems. Although decrements of pH significantly reduced the tested morphophysiological and biochemical attributes in all the cultivars, there was high variability among the cultivars in response to the varying pH of the growing media. Acidity stress reduced growth, biomass, water content, and chlorophyll content in all the cultivars. However, BARI Gom-26 showed the least damage, with the lowest H2O2 generation, lipid peroxidation (MDA), and greater membrane stability, which indicate better tolerance against oxidative damage. In addition, the antioxidant defense components, ascorbate (AsA) and glutathione (GSH), and their redox balance were higher in this cultivar. Maximum H2O2 scavenging due to upregulation of the antioxidant enzymes [AsA peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), GSH reductase (GR), GSH peroxidase (GPX), and GSH-S-transferase (GST)] was observed in BARI Gom-26, which also illustrated significant enhancement of methylglyoxal (MG) detoxification by upregulating glyoxalase I (Gly I) and glyoxalase II (Gly II). This study also showed that balanced essential nutrient content as well as lower toxic micronutrient content was found in BARI Gom-26. Therefore, considering the physiological and biochemical attributes and growth, we conclude that BARI Gom-26 can withstand acidity stress during the early seedling stage, by regulating the coordinated action of the antioxidant defense and glyoxalase systems as well as maintaining nutrient balance.
ABSTRACT
The present study was designed to investigate the duration-dependent changes in the biochemical attributes of sesame in response to waterlogging stress. Sesame plants (Sesamum indicum L. cv. BARI Til-4) were subjected to waterlogging for 2, 4, 6, and 8 days during the vegetative stage and data were measured following waterlogging treatment. The present study proves that waterlogging causes severe damage to different attributes of the sesame plant. The plants showed an increasing trend in lipid peroxidation as well as hydrogen peroxide (H2O2) and methylglyoxal contents that corresponded to increased stress duration. A prolonged period of waterlogging decreased leaf relative water content and proline content. Photosynthetic pigments, like chlorophyll (chl) a, b, and chl (a+b) and carotenoid contents, also decreased over time in stressed plants. Glutathione (GSH) and oxidized glutathione (GSSG) contents increased under waterlogging, while the GSH/GSSG ratio and ascorbate content decreased, indicating the disruption of redox balance in the cell. Ascorbate peroxidase, monodehydroascorbate reductase, and glutathione peroxidase activity increased under waterlogging, while dehydroascorbate reductase, glutathione reductase, and catalase activity mostly decreased. Waterlogging modulated the glyoxalase system mostly by enhancing glyoxalase II activity, with a slight increase in glyoxalase I activity. The present study also demonstrates the induction of oxidative stress via waterlogging in sesame plants and that stress levels increase with increased waterlogging duration.
