Identification and characterization of core abscisic acid (ABA) signaling components and their gene expression profile in response to abiotic stresses in Setaria viridis

Karoline Estefani Duarte,Pierre Roger René Marraccini,Hugo Bruno Correa Molinari,Bárbara Andrade Dias Brito Da Cunha,Thaís Ribeiro Santiago,Ana Paula Ribeiro,Bruno Leite Sampaio,Michelle Guitton Cotta,Adilson Kenji Kobayashi,Wagner Rodrigo De Souza

doi:10.1038/s41598-019-40623-5

Abstract

Abscisic acid (ABA) is an essential phytohormone that regulates growth, development and adaptation of plants to environmental stresses. In Arabidopsis and other higher plants, ABA signal transduction involves three core components namely PYR/PYL/RCAR ABA receptors (PYLs), type 2C protein phosphatases (PP2Cs) and class III SNF-1-related protein kinase 2 (SnRK2s). In the present study, we reported the identification and characterization of the core ABA signaling components in Setaria viridis, an emerging model plant for cereals and feedstock crops presenting C4 metabolism, leading to the identification of eight PYL (SvPYL1 to 8), twelve PP2C (SvPP2C1 to 12) and eleven SnRK2 (SvSnRK2.1 through SvSnRK2.11) genes. In order to study the expression profiles of these genes, two different S. viridis accessions (A10.1 and Ast-1) were submitted to drought, salinity and cold stresses, in addition to application of exogenous ABA. Differential gene expression profiles were observed in each treatment and plant genotype, demonstrating variations of ABA stress responses within the same species. These differential responses to stresses were also assessed by physiological measurements such as photosynthesis, stomatal conductance and transpiration rate. This study allows a detailed analysis of gene expression of the core ABA signaling components in Setaria viridis submitted to different treatments and provides suitable targets for genetic engineering of C4 plants aiming tolerance to abiotic stresses.

Highlights

Abscisic acid (ABA) is an essential phytohormone that regulates growth, development and adaptation of plants to environmental stresses
The class III SNF1-related protein kinases 2 (SnRK2s) are the most implicated in positive regulation of ABA signaling, especially because of the strong phenotype observed in the Arabidopsis triple mutant snrk2.2/2.3/2.6, which could germinate and grow on 50 μM ABA, an abnormal phenotype demonstrated by ABA-insensitive mutants[18]
It was possible to identify in SvPYL proteins a conserved motif 1 related to the well-known “GATE” and “LATCH” loop regions and motifs 2–3 involved in ABA binding (Fig. 1A)

Summary

Introduction

Abscisic acid (ABA) is an essential phytohormone that regulates growth, development and adaptation of plants to environmental stresses. In Arabidopsis and other higher plants, ABA signal transduction involves three core components namely PYR/PYL/RCAR ABA receptors (PYLs), type 2C protein phosphatases (PP2Cs) and class III SNF-1-related protein kinase 2 (SnRK2s). This study allows a detailed analysis of gene expression of the core ABA signaling components in Setaria viridis submitted to different treatments and provides suitable targets for genetic engineering of C4 plants aiming tolerance to abiotic stresses. ABA receptors were first uncovered in Arabidopsis, where three core components have been identified: the ABA receptor PYR/PYL/RCAR (PYL) protein family, the negative regulator type 2C protein phosphatase (PP2C) and the positive regulator class III SNF-1-related protein kinase 2 (SnRK2) Some of these receptors were identified in other plant species such as sorghum, maize and rubber tree[12,13,14]. This study provides suitable targets for genetic engineering of C4 plants aiming tolerance to abiotic stresses

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