The SCL30a SR protein regulates ABA‐dependent seed traits and germination under stress

• Published in: Plant, cell and environment Vol. 46; no. 7; pp. 2112 - 2127
• Main Authors: Laloum, Tom, Carvalho, Sofia D., Martín, Guiomar, Richardson, Dale N., Cruz, Tiago M. D., Carvalho, Raquel F., Stecca, Kevin L., Kinney, Anthony J., Zeidler, Mathias, Barbosa, Inês C. R., Duque, Paula
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01-07-2023
• Subjects: Abscisic acid; abscisic acid (ABA); Abscisic Acid - metabolism; Abscisic Acid - pharmacology; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biosynthesis; Epistasis; Gene expression; Gene Expression Regulation, Plant; Germination; Germination - physiology; Hypersensitivity; Hypersensitivity (delayed); Mutants; Proteins; RNA-binding protein; Seed germination; Seeds; Sensitivity analysis; Serine-Arginine Splicing Factors - genetics; Serine-Arginine Splicing Factors - metabolism; SR proteins; stress response; Transcriptomes; Transgenic plants; Arabidopsis thaliana; SR proteins; abscisic acid (ABA); stress response; seed germination
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.14593

SR proteins are conserved RNA‐binding proteins best known as splicing regulators that have also been implicated in other steps of gene expression. Despite mounting evidence for a role in plant development and stress responses, the molecular pathways underlying SR protein regulation of these processes remain poorly understood. Here we show that the plant‐specific SCL30a SR protein negatively regulates ABA signaling to control seed traits and stress responses during germination in Arabidopsis. Transcriptome‐wide analyses revealed that loss of SCL30a function barely affects splicing, but largely induces ABA‐responsive gene expression and genes repressed during germination. Accordingly, scl30a mutant seeds display delayed germination and hypersensitivity to ABA and high salinity, while transgenic plants overexpressing SCL30a exhibit reduced ABA and salt stress sensitivity. An ABA biosynthesis inhibitor rescues the enhanced mutant seed stress sensitivity, and epistatic analyses confirm that this hypersensitivity requires a functional ABA pathway. Finally, seed ABA levels are unchanged by altered SCL30a expression, indicating that the gene promotes seed germination under stress by reducing sensitivity to the phytohormone. Our results reveal a new player in ABA‐mediated control of early development and stress response.
Summary statement
We found that an Arabidopsis SR protein represses ABA‐induced gene expression to modulate seed traits and germination. Our results uncover a new player in ABA‐mediated control of early plant development and stress responses.