Co-expression of stress-responsive regulatory genes, MuNAC4, MuWRKY3 and MuMYB96 associated with resistant-traits improves drought adaptation in transgenic groundnut (Arachis hypogaea l.) plants

Abstract

Groundnut, cultivated under rain-fed conditions is prone to yield losses due to intermittent drought stress. Drought tolerance is a complex phenomenon and multiple gene expression required to maintain the cellular tolerance. Transcription factors (TFs) regulate many functional genes involved in tolerance mechanisms. In this study, three stress-responsive regulatory TFs cloned from horse gram, (Macrotyloma uniflorum (Lam) Verdc.), MuMYB96, involved in cuticular wax biosynthesis; MuWRKY3, associated with anti-oxidant defense mechanism and MuNAC4, tangled with lateral root development were simultaneously expressed to enhance drought stress resistance in groundnut (Arachis hypogaea L.). The multigene transgenic groundnut lines showed reduced ROS production, membrane damage, and increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) enzyme activity, evidencing improved antioxidative defense mechanisms under drought stress. Multigene transgenic plants showed lower proline content, increased soluble sugars, epicuticular wax content and higher relative water content suggesting higher maintenance of tissue water status compared to wildype and mock plants. The scanning electron microscopy (SEM) analysis showed a substantial increase in deposition of cuticular waxes and variation in stomatal number in multigene transgenic lines compared to wild type and mock plants. The multigene transgenic plants showed increased growth of lateral roots, chlorophyll content, and stay-green nature in drought stress compared to wild type and mock plants. Expression analysis of transgenes, MuMYB96, MuWRKY3, and MuNAC4 and their downstream target genes, KCS6, KCR1, APX3, CSD1, LBD16 and DBP using qRT-PCR showed a two- to four-fold increase in transcript levels in multigene transgenic groundnut plants over wild type and mock plants under drought stress. Our study demonstrate that introducing multiple genes with simultaneous expression of genes is a viable option to improve stress tolerance and productivity under drought stress.

Transcriptome profiling, physiological, and biochemical analyses provide new insights towards drought stress response in sugar maple (Acer saccharum Marshall) saplings

“…One-way ANOVA was used to estimate the significant differences between drought stress treatments on various physiological and biochemical traits and gene expression studies (Pandian et al, 2020). The R package ggplot2 was used to generate bar graphs (Wickham and Wickham, 2007;Vennapusa et al, 2022). Fisher's LSD test was used to separate the mean of significant treatments at P ≤ 0.05 by using the R package agricolae (de Mendiburu, 2020; Pandian et al, 2021).…”

“…At cellular and molecular levels, a significant effect of drought stress is seen on turgor pressure maintenance, membrane stability, sugar metabolism, respiration, interruption of metabolic and biochemical pathways, protein degradation, enzyme dysfunctions, induction of stress signaling, and sensitive genes ( Farooq et al., 2009 ; McDowell, 2011 ). Plants cope with drought stress through various mechanisms, such as morphological by water mining with profound root systems, conservation by waxes, reduced leaf size, stay green nature, growth and development, and physiological mechanisms by maintaining the photosynthetic machinery, assimilate partitioning, stomatal regulation, turgor maintenance ( Anjum et al., 2011 ; Sajeevan et al., 2017 ; Seleiman et al., 2021 ; Venkatesh et al., 2022 ). Biochemical mechanisms involved osmolyte and secondary metabolite production, enzymatic functions, maintenance of metabolic, protein, and lipid biosynthetic pathways, and molecular mechanisms involved in the maintenance of RNA and DNA synthesis and stress signaling, cascade, and regulatory genes expression, especially the stress-induced transcription factors, and stress-responsive downstream genes ( Mickelbart et al., 2015 ; Kiranmai et al., 2018 ; Lokesh et al., 2019 ; Zhang et al., 2022 ).…”

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

“…Co-expression of abiotic stress-responsive transcription Factors such as AtDREB2A, AtHB7 , and AtABF3 delivered improved salinity and drought tolerance in peanuts ( Pruthvi et al., 2014 ). Venkatesh et al., 2022 reported the pyramiding of multiple genes belonging to three different transcription factor families, MuMYB96 , MuWRKY3 , and MuNAC4 , from a hardy crop horse gram ( Macrotyloma uniflorum ) showed improved drought stress tolerance by acquiring the water conservation, water mining, and cellular level tolerance traits in groundnut, and maintained sustained yield and physiological functions. Co-expression of eIF4A1 with NHX1 (Na +/H + antiporter), enhances tolerance to drought in sweet potato by improving ROS scavenging activity and by maintaining membrane integrity ( Zhang et al., 2019 ).…”

Sustaining yield and nutritional quality of peanuts in harsh environments: Physiological and molecular basis of drought and heat stress tolerance

“…Induce lateral root growth Drought Pandurangaiah et al (2014), Venkatesh et al (2022) Frontiers in Genetics frontiersin.org edited plant offspring, they are assigned a non-regulated status (Ahmad et al, 2021), such as the common button mushroom modified by the CRISPR system obtained a non-regulated status in 2016 (Waltz, 2016). 'Sanatech Seed' has launched the world's first genome-edited high-GABA tomato with enhanced nutritional benefits for consumption in Japan.…”