Study of low light stress on molecular regulation and yield performance of rice (Oryza sativa L.)
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Date
2022-11-05
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Department of Plant Physiology, OUAT, Bhubaneswar
Abstract
Light has a significant role in the growth and development of plants because of its crucial role in photosynthesis and photomorphogenesis. To respond to various environmental stimuli, plants have evolved various morpho-physiological modifications. Different light signals have a huge influence on plant growth and development. If the amount of light intensity reaching the plants is less than the optimum level, plants suffer from low light stress, and crop production suffers as a result. Rice, the most important food crop, is extremely sensitive to low light stress, and a marked yield reduction have been observed in eastern and north eastern countries. The current experiment was titled "Study of low light stress on molecular regulation and yield performance of rice (Oryza sativa L.)" based on the facts stated above. The entire experiment was carried out in the Division of Crop Physiology and Biochemistry research plot at the National Rice Research Institute in Cuttack, India. During the Kharif (wet) seasons of 2019-20 and 2020-21, the experiment was carried out in both the field and the net house. Initially, 50 long-duration rice genotypes were chosen for screening, and 11 of them were picked, along with susceptible and tolerant controls based on yield reduction, for further morphological, physiological, biochemical, and molecular studies. Three replications of selected genotypes were grown under normal light (100% light), 75% light, and 50% light treatments. Plant height, tiller number, and leaf area were measured during the vegetative stage, and stem dry weight, panicle dry weight, and plant dry weight were measured at 50% flowering, 7 days after 50% flowering, 14 days after 50% flowering, and harvest. Physiological and biochemical observations were made at the 50% flowering stage. Grain quality parameters such as head rice recovery, milling recovery, alkali spreading value, water uptake, kernel length after cooking, water uptake, and gel consistency were measured on harvested seeds with less than 14% moisture content. To better understand the mechanism of the low light stress response, RT-PCR analysis was used to examine gene expression. Among the eleven genotypes, Nalini Sali and Nasati Sali, as well as the tolerant control variety Swarnaprabha, are the least affected by low light stress. Plant morphology is more affected under 75% light and 50% light stress, and yield is drastically reduced under 50% light intensity. Physiological parameters such as photosynthetic rate, stomatal conductance, and transpiration rate were found to be directly related to rice variety yield performance under stress conditions. Starch and photosynthesis genes like GBSS-I, ADPG, SS-III, Fru-1-6-BP, Sed-1-7-BP, and RuBisCo are directly regulated by light and thus downregulated in low light conditions However, the gene CAB-2 behaves differently because it is up regulated in response to low light stress. Because the Nalini Sali and Nasati Sali varieties performed better under low light stress, they are considered tolerant. At the same time, Kolabardhan and Na Sali were considered susceptible varieties due to their poor performance.