Arabidopsis SKP1-like protein 13 (ASK13) positively regulates seed germination and seedling growth under abiotic stresses

Abstract

SKP1 (S-Phase Kinase Associated Protein1) proteins are key members of the SCF (SKP-Cullin-F-box protein) E3 ligase complexes that ubiquitinate the target proteins and play diverse roles in plant biology. However, as compared to other members of the SCF complex, study of SKP1-like proteins is very limited in plants. In the present work, we report that Arabidopsis SKP1-like protein13 (ASK13) is differentially regulated in different organs, during seed development and germination, and is upregulated in response to abiotic stresses. Y2H library screening and subsequent in vivo interaction through BiFC analysis revealed that ASK13 not only interacts with F-box proteins but also with other proteins which are not components of SCF complexes. Biochemical analysis revealed that ASK13 not only exists as a monomer but also as a homo-oligomer or heteromer with other ASK proteins. Functional analysis using ASK13 overexpression and knockdown lines revealed that ASK13 positively influences seed germination and seedling growth particularly under abiotic stresses. Taken together, our data strongly suggests that apart from participation to form SCF complexes, ASK13 interacts with several other proteins and is implicated in different cellular processes distinct from protein degradation. Overall, ASK13 positively regulates seed germination and seedling growth particularly under abiotic stress conditions.