Sulfate availability affects ABA levels and germination response to ABA and salt stress in Arabidopsis thaliana

Abstract

SUMMARYSulfur-containing compounds play a critical role in the response of plants to abiotic stress factors including drought. The phytohormone abscisic acid (ABA) is the key regulator of responses to drought and high-salt stress. However, our knowledge about interaction of S-metabolism and ABA biosynthesis is scarce. Here we report that sulfate supply affects synthesis and steady-state levels of ABA in Arabidopsis wild-type seedlings. By using different mutants of the sulfate uptake and reduction pathway, we confirmed the impact of sulfate supply on steady-state ABA content in Arabidopsis and demonstrated that this impact was due to cysteine availability. Loss of the chloroplast sulfate transporter3;1 function (sultr3;1) resulted in significantly decreased aldehyde oxidase (AO) activity and ABA levels in seedlings and seeds. These mutant phenotypes could be reverted by exogenous application of cysteine or ectopic expression of SULTR3;1. In addition the sultr3;1 mutant showed a decrease of xanthine dehydrogenase activity, but not of nitrate reductase, strongly indicating that in seedlings cysteine availability limits activity of the molybdenum co-factor sulfurase, ABA3, which requires cysteine as the S-donor for sulfuration. Transcription of ABA3 and NCED3, encoding another key enzyme of the ABA biosynthesis pathway, was regulated by S-supply in wild-type seedlings. In contrast, ABA up-regulated the transcript level of SULTR3;1 and other S-metabolism-related genes. Our results provide evidence for a significant co-regulation of S-metabolism and ABA biosynthesis that operates to ensure sufficient cysteine for AO maturation and highlights the importance of sulfur for stress tolerance of plants.

Identification of Putative Transmembrane Proteins Involved in Salinity Tolerance in Chenopodium quinoa by Integrating Physiological Data, RNAseq, and SNP Analyses

“…Expression of these quinoa genes is upregulated specifically in either shoot ( AUR62011984 and AUR62021522 ) or root ( AUR62016440 ) tissues. Sulfate is an important component of plant abiotic stress tolerance and may help mediate salt stress tolerance via abscisic acid regulation of leaf stomatal conductance (Ernst et al, 2010) or by promoting synthesis of glutathione, which plays a role in cellular redox balance (Cao et al, 2014). Upregulation of sulfate transporters in the root may lead to increased sulfate uptake while increased expression in the shoot may result in increased transport of sulfate to specific aerial tissues.…”

LSU network hubs integrate abiotic and biotic stress responses via interaction with the superoxide dismutase FSD2

“…It is possible that, similarly to ethylene, LSUs function upstream of ABA. This appears unlikely given that S limitation negatively impacts ethylene biosynthesis due to reduced methionine availability (Bürstenbinder et al , 2007) and also leads to drastically reduced ABA levels (Cao et al , 2014). We therefore hypothesize that LSU proteins may participate in an alternative mechanism to trigger stomatal closure in some stress conditions.…”

Drought stress in maize causes differential acclimation responses of glutathione and sulfur metabolism in leaves and roots

“…The enhanced sulfide levels will activate endogenous in vivo SERAT activity without affecting extractable SERAT amount due to formation of the cysteine synthase complex [44, 59]. Besides the beneficial impact of enhanced cysteine concentration in drought-stressed roots for ABA production [4], methionine synthesis, translation and consequently growth (reviewed in [15, 60]), roots were able to ameliorate their glutathione redox state by increasing total glutathione [61]. Significant transcriptional induction of the GSH1 gene in roots likely contributed to the increase of glutathione in roots.…”

“…Abscisic acid (ABA) plays a key role in root-to-shoot signaling and in the partial or complete stomatal closure to reduce transpiration [3]. Recently, sulfate has been shown to promote ABA synthesis [4] and was found to be transported earlier than ABA from the root to the shoot upon drought stress [5]. In addition to stomata closure, drought-induced ABA triggers many physiological responses like glycinebetaine production and root growth of maize plants [6].…”