Overexpression of ß-Ketoacyl Co-A Synthase1 Gene Improves Tolerance of Drought Susceptible Groundnut (Arachis hypogaea L.) Cultivar K-6 by Increased Leaf Epicuticular Wax Accumulation

Abstract

Drought is one of the major environmental constraints affecting the crop productivity worldwide. One of the agricultural challenges today is to develop plants with minimized water utilization and reduced water loss in adverse environmental conditions. Epicuticular waxes play a major role in minimizing water loss. Epicuticular wax covers aerial plant parts and also prevents non-stomatal water loss by forming the outermost barrier from the surfaces. Epicuticular wax content (EWC) variation was found to be affiliated with drought tolerance of groundnut cultivars. In the current study, a fatty acid elongase gene, KCS1, which catalyzes a rate limiting step in the epicuticular wax biosynthesis was isolated from drought tolerant cultivar K-9 and overexpressed in drought sensitive groundnut cultivar (K-6) under the control of CaMV35S constitutive promoter. Transgenic groundnut plants overexpressing AhKCS1 exhibited normal growth and displaying greenish dark shiny appearance. Environmental scanning electron microscopy (ESEM) revealed the excess of epicuticular wax crystal depositions on the transgenic plant leaves compared to non-transgenic wild type plants. The findings were further supported by gas chromotography–mass spectroscopic analysis (GC-MS) that revealed enhanced levels of fatty acids, secondary alcohols, primary alcohols, aldehydes, alkanes, and ketones in transgenics compared to wild types. The AhKCS1 overexpressing transgenic groundnut plants exhibited increase in the cuticular wax content, reduction of water loss, lower membrane damage, decreased MDA content, and high proline content compared to that of non-transgenic groundnut plants. Our findings suggest that the AhKCS1 gene plays a major role in combating drought stress by preventing non-stomatal water loss in drought sensitive groundnut cultivar (K-6).

Transcriptional analyses of maize leaves in response to high‐density planting

“…The de novo synthesis of cuticular wax is initiated from C16 or C18 FAs by various enzymes and transporters, including fatty acyl‐CoA reductase, β‐ketoacyl‐CoA synthase (KCS), and acyl carrier protein (Lewandowska et al., 2020). Consistent with previous studies showing stress‐induced overexpression of KCS1 and ACP4 genes (Lokesh et al., 2019; Wang et al., 2016), two KCS1 genes ( GRMZM2G104626 and GRMZM2G149636 ) were significantly upregulated in the lower leaves under HDP, indicating a functional role in the stress responses. Additionally, two ACP4 genes were differentially expressed in the lower leaves in response to HDP.…”

Genome-Wide Identification and Expression Profiling of KCS Gene Family in Passion Fruit (Passiflora edulis) Under Fusarium kyushuense and Drought Stress Conditions

“…In addition, the KCS family members have been functionally characterized in Arabidopsis ( Lee et al, 2009 ; Kim et al, 2013 ; Hegebarth et al, 2017 ), C. sinensis ( Yang H. et al, 2021 ; Wang et al, 2022 ), O . sativa ( Wang X. et al, 2017 ), H. annuus ( González-Mellado et al, 2019 ), S. tuberosum ( Serra et al, 2009 ), M. domestica ( Lian et al, 2021 ), V. vinifera ( Yang Z. et al, 2020 ), and A. hypogaea ( Lokesh et al, 2019 ). However, information about the KCS gene family in passion fruit was unknown and the availability of the passion fruit genome ( Ma et al, 2021 ) made it possible to study on genomic levels.…”

“… Yang Z. et al (2020) reported that ectopic overexpression of grape ( Vitis vinifera ) VvKCS in Arabidopsis enhanced the tolerance to salt stress at germination and seedling stages. Overexpression of AhKCS 1 in groundnut ( Arachis hypogaea ) ( Lokesh et al, 2019 ) increased the cuticular waxes and reduced membrane damage under drought stress conditions. Overexpression of BnKCS 1-1/ BnKCS 1-2 in rapeseed ( Brassica napus ) exhibited increased wax concentration and tolerance to drought under drought conditions ( Wang Y. et al, 2020 ).…”

Ectopic Expression of CsKCS6 From Navel Orange Promotes the Production of Very-Long-Chain Fatty Acids (VLCFAs) and Increases the Abiotic Stress Tolerance of Arabidopsis thaliana

“…Recently, several KCS family genes from different plant species were reported to play an important role in regulating cuticle permeability and plant tolerance to abiotic stress. For example, overexpression of AhKCS1 from a drought tolerant groundnut reduced the cuticle permeability and enhanced the drought tolerance in a susceptible genotype by increasing cuticular wax load in leaves ( Lokesh et al, 2019 ). Overexpression of BnKCS1-1 and BnKCS1-2 in Brassica napus also increased drought tolerance in transgenic plants by promoting cuticular wax production ( Wang et al, 2020 ).…”