ABSTRACT
Supplemental (s)-UV-B radiation has adverse effects on the majority of plants. The present study was conducted to evaluate the effects of exogenous application of the growth hormone indole acetic acid (IAA) on various morphological, physiological and biochemical characteristics of Withania somnifera, an indigenous medicinal plant, subjected to s-UV-B. The s-UV-B-treated plants received ambient + 3.6 kJm-2 ·day-1 biologically effective UV-B, and IAA was applied at two doses (200 and 400 ppm) to s-UV-B-exposed plants. The plant was forced to compromise its growth, development and photosynthetic patterns to survive under s-UV-B by increasing concentrations of secondary metabolites and antioxidants (thiol, proline, ascorbic acid, α-tocopherol, ascorbate peroxidase, catalase, glutathione reductase, peroxidase, polyphenol oxidase, superoxide dismutase) to counteract oxidative stress. Increases in secondary metabolites were evidenced as increased activity of phenylpropanoid pathway enzymes: phenylalanine ammonia lyase, cinnamyl alcohol dehydrogenase, 4-coumarate CoA ligase, chalcone isomerase and dihydroflavonol reductase. Application of different IAA doses reversed the detrimental effects of s-UV-B on W. somnifera by improving growth and photosynthesis and reducing concentrations of secondary metabolites and non-enzymatic antioxidants. Antioxidant enzymes, however, had a synergistic effect on s-UV-B treatment and IAA application. The effects of s-UV-B on W. somnifera are ameliorated to varying degrees upon exogenous IAA application, and synergistic enhancement of antioxidant enzymes under s-UV-B+IAA treatment might be responsible for the partial recuperation of growth and plant protein content, as a UV-B-exposed plant is forced to allocate most of its photosynthate towards production of enzymes related to antioxidant defence.
Subject(s)
Indoleacetic Acids/pharmacology , Plant Growth Regulators/pharmacology , Withania/drug effects , Dose-Response Relationship, Radiation , Oxidative Stress/drug effects , Oxidative Stress/radiation effects , Photosynthesis/drug effects , Photosynthesis/radiation effects , Plants, Medicinal/drug effects , Plants, Medicinal/radiation effects , Ultraviolet Rays , Withania/metabolism , Withania/radiation effectsABSTRACT
The chemically as well as hot water treated agrowaste sugarcane bagasse was subjected to degradation by Pleurotus citrinopileatus. The fungus degraded lignin, cellulose, hemicellulose, and carbon content of both chemically as well as hot water treated waste and produced in turn the edible and nutritious fruiting body. Biodegradation of the waste in terms of loss of lignin, cellulose and hemicellulose showed positive correlation with cellulases, xylanase, laccase and polyphenol oxidase (PPO) activity of the fungus. During mycelial growth of the fungus, lignin degradation was faster and during fructification, lignin degradation was slower than cellulose and hemicellulose. The carbon content of the sugarcane bagasse decreased while, nitrogen content increased during degradation of the waste. Hot water treated substrate supported better production of enzymatic activity and degraded more efficiently than chemically sterilized substrate. The total yield and biological efficiency of the mushroom was maximum on the hot water treated substrates. Degradation of the hot water treated sugarcane bagasse was better and faster than chemically treated substrates.
