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

作者：Pri Tal Oded; Shaar Moshe Lidor; Wiseglass Gil; Peleg Zvi; Mosquna Assaf^*

来源：Plant Journal, 2017, 92(5): 774-786.

DOI：10.1111/tpj.13714

• abscisic acid
• abscisic acid signaling
• PYR
• PYL
• RCAR
• Brachypodium distachyon
• type 2C phosphatases

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 invitro 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.
Significance Statement Genetic evidence indicates that Arabidopsis perceive the stress hormone ABA via a large redundant family of receptors. Although the genome of grass model plant Brachypodium encodes similar number of receptors, the expression of BdPYL1 is predominant and its function during plant development is non-redundant, from seed to maturation. Suggesting a different strategy to stress perception.

• 出版日期2017-12