Impact of water stress on sucrose metabolism in rice (oryza sativa L.)

Abstract

The study entitled “Impact of water stress on sucrose metabolism in rice (Oryza sativa L.)” conducted at Department of Plant Biotechnology and Department of Plant Physiology, College of Agriculture, Vellayani during 2020-21. The objective was to study the impact of water stress on sucrose metabolism by analyzing the physiological and biochemical parameters and gene expression in selective drought tolerant and susceptible rice genotypes. In this study, two rice varieties, drought tolerant variety, PTB 7 (Parambuvattan) and drought susceptible, PTB 23 (Cheriya Aryan) were grown in pot culture and after the panicle initiation stage, crops were subjected to water stress by withdrawing irrigation until the plants experienced the symptoms of stress (leaf rolling). Then the various physiological parameters were studied five days after the induction of water stress. Extraction and estimation of sucrose metabolizing enzymes such as invertase, α- and β-amylase were done five days after induction of stress spectrophotometrically. Expression levels of sucrose synthase (SuSy) and sucrose transporter gene (SUC2) were analyzed from both root and leaf seven days after induction of water stress. Under water stress, physiological parameters such as cell membrane stability index, relative water content and yield trait like number of productive tillers were significantly reduced, activity of enzymes such as invertase, α- and β-amylase were increased and gene expression level of sucrose synthase (SuSy) and sucrose transporter (SUC-2), which are associated with the sucrose metabolism were upregulated. Water stress enhanced the sucrose content and reducing sugar content in rice plant. There was significant increase in root traits in PTB 7 but they were reduced in PTB 23. Also, there was a reduction in shoot biomass than the root biomass in tolerant rice variety, which leads to an increase in root to shoot (R/S) ratio. In this study, sucrose metabolism and transport were increased in both drought tolerant and susceptible variety under water stress condition. However, PTB 7 (drought tolerant) showed an improved sucrose metabolism than PTB 23 (drought susceptible) during water stress condition.