Comprehensive analysis of physiological and metabolomic responses to drought reveals specific modulation of acquired tolerance mechanisms in rice

Abstract

Mild stresses induce "acquired tolerance traits" (ATTs) that provide tolerance when stress becomes severe. Here, we identified the genetic variability in ATTs among a panel of rice germplasm accessions and demonstrated their relevance in protecting growth and productivity under water-limited conditions. Diverse approaches, including physiological screens, association mapping and metabolomics, were adopted and revealed 43 significant marker-trait associations. Nontargeted metabolomic profiling of contrasting genotypes revealed 26 "tolerance-related-induced" primary and secondary metabolites in the tolerant genotypes (AC-39000 and AC-39020) compared to the susceptible one (BPT-5204) under water-limited condition. Metabolites that help maintain cellular functions, especially Calvin cycle processes, significantly accumulated more in tolerant genotypes, which resulted in superior photosynthetic capacity and hence water use efficiency. Upregulation of the glutathione cycle intermediates explains the ROS homeostasis among the tolerant genotypes, maintaining spikelet fertility, and grain yield under stress. Bioinformatic dissection of a major effect quantitative trait locus on chromosome 8 revealed genes controlling metabolic pathways leading to the production of osmolites and antioxidants, such as GABA and raffinose. The study also led to the identification of specific trait donor genotypes that can be effectively used in translational crop improvement activities.

Drought Stress Response in Guar (Cyamopsis tetragonoloba (L.) Taub): Physiological and Molecular Genetic Aspects

“…When drought persists for a long time, and the adaptive capacity of the "drought escape" and "drought avoidance" strategies is insufficient to maintain plant growth and productivity, drought tolerance mechanisms can be activated [47]. At this stage, a profound rearrangement of plant metabolism occurs, and mechanisms such as accumulation of osmoprotective proteins-so-called metabolic adjustment; cell wall reinforcement; ROS detoxification; and an increase in the contents of osmolytes, primary metabolites, predominantly amino acids and sugars-may be involved [36,[48][49][50]. Along with the complex regulatory mechanisms of antioxidant defense, carbohydrate and nitrogen metabolism, including the control of gene expression and the activity of key enzymes [33], significant changes in the composition of osmoprotective metabolites and proteins associated with the drought onset are crucial for plant survival [39,51].…”

Phenotyping and metabolome analysis reveal the role of AdoMetDC and Di19 genes in determining acquired tolerance to drought in rice

“…While these traits are constitutively expressed, more recent experiments point towards the inclusion of specific traits that are upregulated only when plants first experience mild levels of stress. These traits are collectively referred to as acquired tolerance traits (ATTs) and are known to provide significant levels of tolerance to severe stress (Doddaraju et al, 2023; Kadam et al, 2014; Kumar et al, 1999; Lekshmy et al, 2021; Uma et al, 1995). A comprehensive improvement in drought adaptation can be achieved only when the constitutive traits like WUE and root traits are introgressed in the background of a reasonably high propensity for acquiring tolerance at the cellular level (Lekshmy et al, 2021; Raju et al, 2014).…”

Pyramiding of transcription factor, PgHSF4, and stress-responsive genes of p68, Pg47, and PsAKR1 impart multiple abiotic stress tolerance in rice (Oryza sativa L.)

“…In the present study, three different transgenes from hardy crop species, viz, p68 from peanut and Pg47 and PgHSF4 (Heat Shock Transcription Factor 4) from Pennisetum glaucum , which are involved in maintaining RNA stability and translational processes and protein stability were co-expressed along with marker-free gene, PsAKR 1 from Pseudomonas sp reported to involve in abiotic stress tolerance. The rice genotype AC39020 was reported to have superior characteristics of water mining, water use efficiency, and water conservation in response to drought ( Vennapusa et al., 2015 ; Pushpa et al., 2023 ). The multigene-expressing rice lines were developed using the Agrobacterium -mediated in-planta transformation method, assessed the tolerance levels against multiple abiotic stresses, and characterized the physiological and molecular mechanisms responsible for tolerance and associated traits.…”