Abstract
The present study was pertaining to study the mechanism and signaling of BRs under high temperature stress in Brassica juncea L. plants. Results advised that high temperature stress reduced the shoot length, root length, fresh weight of the plants but 28-homobrassinosteroids (28-homoBL) treatment reduced the toxic effect of high temperature stress by improving the same of B. juncea L. plants. To ascertain these free radical scavenging enzymes (superoxide dismutase (SOD), Catalase (CAT), Peroxidase (POD), Ascorbate peroxidase (APOX), Polyphenol oxidase (PPO) and Indole acetic acid oxidase (IAAO) and lipid oxidation (MDA) were assayed along with photosynthetic pigments, total carbohydrates, reducing sugars and non-reducing sugars. All studied scavenging enzymes activities were ameliorated by the homoBL treatments. The pigments decreased under temperature stress were also protected by homoBL treatments. Proteins profiling by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDSPAGE) were also studied to know the behavior of proteins under temperature stress as well as with the treatment of homoBL. Protein bands disappeared in temperature stress while in the presence of homoBL treatment existing proteins displayed more accumulation leading to the appearance of new bands. Native-PAGE of SOD, CAT and POD suggested the presence of in isoenzymic forms in cells. Application of different concentration of homoBL increased intensities of these isoenzymes under temperature and normal condition as compared to control untreated seedlings. The gene expression of SOD and CAT also suggested that synthesis these enzymes were decreased under high temperature stress but ameliorated with the treatment of homoBL. Present study demonstrated that 28-homoBL have stress-ameliorative properties in B. juncea seedlings exposed to high temperature stress by improving seedling growth and enhancing protein content as well as activities of SOD, CAT, APOX, PPO and IAA Oxidase. Further, it was suggested by decreasing the MDA content after the treatments of 28-homoBL. This study demonstrate the culmination of BR’s as an anti-stressor for protection of plant exposed to high temperature stress but extensive studies are still needed to know the various aspects related to stress and role of brassinosteroids in regulating them at molecular and signaling level.
Highlights
It is predicted that increases in “greenhouse gases” concentration will result in the rise in mean temperatures of about 2°C by the middle of the century
High temperatures (“31°C) after anthesis can decrease the rate of grain-filling, whilst high temperatures imposed before anthesis can decrease yield of crop plants
High temperature stress leads to over production of reactive oxygen species (ROS) in plants which are highly reactive and can cause damage to proteins, lipids, carbohydrates, RNA and DNA results in death of cell [1]
Summary
It is predicted that increases in “greenhouse gases” concentration will result in the rise in mean temperatures of about 2°C by the middle of the century. Plants have evolved mechanisms on morphological, physiological and molecular level to survive with modulated environmental conditions [2]. Use of phytohormones is one of the simpler approaches to make crops resistible to negative environmental conditions and perform well by acclimatizing at morphological, physiological, biochemical and molecular level. BRs are very peculiar in regulating the activities of antioxidant defense system at biochemical and regulate the compatible solutes under stress condition in plants. Studies related to the role of brassinosteroids in controlling the metabolic activities of antioxidant defense system enzymes at biochemical and molecular level are available, a comprehensive study is required to gain a deeper insight of the above mechanism. Present study was pertaining to study the mechanism and signaling of BRs under high temperature stress in B. juncea plants. J Plant Biochem Physiol 2: 127. doi:10.4172/2329-9029.1000127
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