Modulations in primary and secondary metabolic pathways and adjustment in physiological behaviour of Withania somnifera under drought stress. (July 2018)

• Record Type: Journal Article
• Authors: Singh, Ruchi; Gupta, Pankhuri; Khan, Furqan; Singh, Susheel Kumar; Sanchita, ; Mishra, Tripti; Kumar, Anil; Dhawan, Sunita Singh; Shirke, Pramod Arvind
• Is Part Of: Plant science. Volume 272(2018)
• Page Start: 42
• Page End: 54
• Publication Date: 2018-07
• Subjects: A net photosynthesis rate -- DW dry weight -- E transpiration rate -- FW fresh weight -- gs stomatal conductance -- GSH reduced glutathione -- GST glutathione-S-transferase -- H2O2 hydrogen peroxide MDA malondialdehyde -- PPFD photosynthetic photon flux density -- ROS reactive oxygen species -- RWC relative water content -- TW turgid weight -- WUE water use efficiency -- OP osmotic potential; Withanolide biosynthesis -- Carbon metabolism -- Drought -- Photosynthesis -- Calvin cycle -- Lnc and miRNAs; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2018.03.029
• Languages: English
• ISSNs: 0168-9452

Abstract

Graphical abstract: Highlights: Downregulation of C2 H2 gene responsible for delayed senescence under drought. Upregulation of SQS shows carbon flux diversion towards phystosterol biosynthesis. Carbon assimilation reduced due to down regulation of calvin cycle gene in drought. SaI, NInv, FBPA and FBPase shows hexokinase mediated sugar signalling in drought. Abstract: In general medicinal plants grown under water limiting conditions show much higher concentrations of secondary metabolites in comparison to control plants. In the present study, Withania somnifera plants were subjected to water stress and data related to drought tolerance phenomenon was collected and a putative mechanistic concept considering growth responses, physiological behaviour, and metabolite content and gene expression aspects is presented. Drought induced metabolic and physiological responses as well as drastic decrease in CO2 uptake due to stomatal limitations. As a result, the consumption of reduction equivalents (NADPH 2+ ) for CO2 assimilation via the calvin cycle declines significantly resulting in the generation of a large oxidative stress and an oversupply of antioxidant enzymes. Drought also results in the shifting of metabolic processes towards biosynthetic activities that consume reduction equivalents. Thus, biosynthesis of reduced compounds (isoprenoids, phenols and alkaloids) is enhanced. The dynamics of various metabolites have been discussed in the light of gene expression analysis of control and drought treated leaves. Gene encoding enzymes of pathways leading to glucose, fructose and fructan production, conversion of triose phosphates to hexoses and hexose phosphorylation were up-regulated in the drought stressed leaves. The down-regulated Calvin cycle genes were co-ordinately regulated with the down-regulation of chloroplast triosephosphate/phosphate translocator, cytoplasmic fructose-1, 6-bisphosphate aldolase and fructose bisphosphatase. Expression of gene encoding Squalene Synthase (SQS) was highly upregulated under drought stress which is responsible for the diversion of carbon flux towards withanolides biosynthesis from isoprenoid pathway.