Abstract
Abscisic acid (ABA) is a key component of the signaling system that integrates plant adaptive responses to abiotic stress. Overexpression of Arabidopsis molybdenum cofactor sulfurase gene (LOS5) in maize markedly enhanced the expression of ZmAO and aldehyde oxidase (AO) activity, leading to ABA accumulation and increased drought tolerance. Transgenic maize (Zea mays L.) exhibited the expected reductions in stomatal aperture, which led to decreased water loss and maintenance of higher relative water content (RWC) and leaf water potential. Also, transgenic maize subjected to drought treatment exhibited lower leaf wilting, electrolyte leakage, malondialdehyde (MDA) and H2O2 content, and higher activities of antioxidative enzymes and proline content compared to wild-type (WT) maize. Moreover, overexpression of LOS5 enhanced the expression of stress-regulated genes such as Rad 17, NCED1, CAT1, and ZmP5CS1 under drought stress conditions, and increased root system development and biomass yield after re-watering. The increased drought tolerance in transgenic plants was associated with ABA accumulation via activated AO and expression of stress-related gene via ABA induction, which sequentially induced a set of favorable stress-related physiological and biochemical responses.
Highlights
Drought stress is one major environmental stress that adversely affects crop growth and productivity worldwide
The goal of the current study was to evaluate the effect of overexpression of Arabidopsis LOS5 in maize subjected to drought stress
We evaluated whether overexpression of LOS5, which increased drought tolerance in maize, lead to phenotypic changes in the expression patterns of stress-responsive genes in transgenic maize
Summary
Drought stress is one major environmental stress that adversely affects crop growth and productivity worldwide. ABA is a key component of the signaling system that integrates the adaptive response of plants to abiotic stress including drought and salinity. It is involved in plant responses to regulation of growth and development, including shoot and root growth, and leaf transpiration [1]. ABA accumulation in plant cells occurs quickly as plants respond to drought stress, which promotes expression of ABA-inducible genes [4] and stomatal closure to reduce transpirational water loss [5]. Putative high ABA content induced stomatal closure, which is important for plant tolerance of water stress [6]. An important strategy for plant drought tolerance is regulation of stomatal movement by ABA actions
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