Non‐redundant functions of the dimeric ABA receptor BdPYL1 in the grass Brachypodium

Abstract

Abiotic stresses have severe detrimental effects on agricultural productivity worldwide. Abscisic acid (ABA) levels rise in response to abiotic stresses, and play a role in coordinating physiological responses. ABA elicits its effects by binding a family of soluble receptors, increasing affinity of the receptors to type 2C phosphatases (PP2Cs) leading to phosphatase inhibition. In the current study, we conducted a comprehensive analysis of the ABA signaling pathway in the cereal model grass Brachypodium distachyon. The Brachypodium genome encodes a family of 10 functionally conserved ABA receptors. The 10th in the series, BdPYL10, encodes a defective receptor and is likely a pseudogene. Combinatorial protein interaction assay further validated computational analysis, which grouped Brachypodium ABA receptors into three subfamilies, similarly to Arabidopsis classification. Brachypodium subfamily III receptors inhibited PP2C activity in vitro and complemented Arabidopsis quadruple (pyr1/pyl1/pyl2/pyl4) mutant. BdPYL1 T-DNA mutant exhibited clear ABA hyposensitivity phenotypes during seedling establishment and in mature plants. Single receptor predominance is in agreement with high transcriptional abundance of only a small Brachypodium ABA receptors subset, harboring the higher marginal significance of BdPYL1. Our findings suggest that unlike the highly redundant ABA core signaling components of Arabidopsis, Brachypodium encompasses a more compact and specialized ABA receptor apparatus. This organization may contribute to plant adaptations to ecological niches. These results lay the groundwork for targeting the prominent ABA receptors for stress perception in grasses, and reveal functional differences and commonalities between monocots and eudicots.

Optimized small‐molecule pull‐downs define MLBP1 as an acyl‐lipid‐binding protein

“…auxotrophic mutants in a given metabolic pathway may narrow down the range of possible molecule ligands). To test the protein–ligand co‐purification protocol in A. thaliana , we generated transgenic plants stably expressing PYL5 and two transgenic controls expressing PYL5 K87A, a mutant in one of the key ABA‐binding residues (Melcher et al ., ), or GFP (Pri‐Tal et al ., ). Expression of the proteins was driven by 35S and tagged by HPB .…”

“…The restriction sites generated to clone each START domain‐encoding gene are referred to in the primer name (Table S3). Coding sequences were then inserted into the pHeGHPB (Pri‐Tal et al ., ) linearized expression vector in either Age I and Eco RI, Xma I or Xma I and Xho I restriction sites. ΔN HAB1 was cloned into the pEGAD (Cutler et al ., ) binary vector using the Eco RI and Xho I restriction enzymes harboring a GFP translational fusion.…”

“…All START domain-encoding genes were cloned in a translational fusion to a biotinylation tag sequence and expressed under the 35S constitutive promoter (Pri-Tal et al, 2017). An RNA mixture from A. thaliana Col-0 seedlings, seeds, flowers and fruits was isolated using the Concert TM Plant RNA Reagent.…”

Effects of Exogenous Abscisic Acid (ABA) on Carotenoids and Petal Color in Osmanthus fragrans ‘Yanhonggui’

“…It has been proven that pale flowers have fewer carotenoids than more deeply colored flowers [7]. Furthermore, the ABA-signaling pathway is a complicated network, which includes ABA receptors (ABARs) [46], type 2C phosphatases (PP2Cs) [47], ABRE-binding factors (ABFs) [48], and other proteins. Further investigation would be the measurement of ABA and the contribution of endogenous and absorbed exogenous ABA on the carotenoids metabolic pathway, and the mechanism of the ABA-signaling pathway on carotenoid metabolism to elucidate the mechanism of petal color change in O. fragrans treated with ABA.…”

The fungal sesquiterpenoid pyrenophoric acid B uses the plant ABA biosynthetic pathway to inhibit seed germination

“…Finally, 118 abscisic aldehyde is used as substrate by the aldehyde oxidase AAO3, in a reaction that 119 depends on the activity of the molybdenum cofactor sulfurase ABA3, to produce ABA ( 120 Schwartz et al, 1997;Seo et al, 2000;González-Guzmán et al, 2004). ABA is 121 perceived by the PYR/PYL/RCAR family of ABA receptors, comprised of 14 members 122 in the eudicot plants Arabidopsis and tomato and 12 and 9 members in the monocot 123 species rice and Brachypodium distachyon, respectively (Ma et al, 2009;Park et al, 124 2009;He et al, 2014;Pri-Tal et al, 2017). ABA-bound PYR/PYL/RCAR proteins 125 interact with Protein Phosphatases type 2C (PP2C) and inhibit their activity allowing the 126 downstream phosphorylation cascades to activate the ABA response, including inhibition 127 of seed germination and stomatal closure, among others.…”