Chemical manipulation of plant water use

Abstract

Agricultural productivity is dictated by water availability and consequently drought is the major source of crop losses worldwide. The phytohormone abscisic acid (ABA) is elevated in response to water deficit and modulates drought tolerance by reducing water consumption and inducing other drought-protective responses. The recent identification of ABA receptors, elucidation of their structures and understanding of the core ABA signaling network has created new opportunities for agrochemical development. An unusually large gene family encodes ABA receptors and, until recently, it was unclear if selective or pan-agonists would be necessary for modulating water use. The recent identification of the selective agonist quinabactin has resolved this issue and defined Pyrabactin Resistance 1 (PYR1) and its close relatives as key targets for water use control. This review provides an overview of the structure and function of ABA receptors, progress in the development of synthetic agonists, and the use of orthogonal receptors to enable agrochemical control in transgenic plants.

Recent Advances in Plant Chemical Biology of Jasmonates

“…However, there are few successful examples of 'biased' plant hormone receptor agonists. Cutler's group successfully developed the ABA receptor agonists [39] pyrabactin [40,41], quinabactin [42], cyanabactin [43], and opabactin [44], which were identified by random screening of a large-scale chemical library, and exhibited remarkable selectivity among 15 ABA receptor subtypes. The same method also resulted in the identification of SPL7, a femtomolar agonist selective for a strigolactone receptor ShHTL7 involved in the seed germination of parasitic plant Striga hermonthica [45].…”

The role of water in plant–microbe interactions

“…Drought treatment or Pst DC3000 infection are both known to increase the accumulation of ABA in plants (reviewed in Ton et al, 2009;Helander et al, 2016). ABA promotes stomatal closure, which prevents bacteria from entering through stomata (Eisenach and de Angeli, 2017;Inoue and Kinoshita, 2017;Vialet-Chabrand et al, 2017).…”

“…Among these bacteria, Bacillus licheniformis Rt4M10 and Pseudomonas fluorescens Rt6M10 can produce several plant hormones, including ABA, indole-3acetic acid (IAA) and gibberellin (Salomon et al, 2014). ABA induces stomatal closure to reduce water consumption in plants and improve their drought tolerance (reviewed in Helander et al, 2016). Inoculation with the two ABA-producing bacterial strains significantly increases the ABA level in the inoculated plants (Salomon et al, 2014), protecting the plants from drought stress.…”

Over‐accumulation of abscisic acid in transgenic tomato plants increases the risk of hydraulic failure

“…The use of chemical ABA receptor agonists to activate ABA receptors and to increase ABA signalling has agronomic promise (Helander, Vaidya, & Cutler, 2016), and transgenic approaches to increase ABA biosynthesis and signalling have been successful in enhancing WUE. Overexpression of the rate-limiting enzyme in ABA biosynthesis, 9-cis-epoxycarotenoid dioxygenase (NCED), led to increased ABA accumulation (Thompson et al, 2000), lower stomatal conductance, and up to 79% higher gravimetric transpiration efficiency (another term for WUE) with only small effects on photosynthetic carbon assimilation or growth (Thompson, Andrews, et al, 2007).…”