Characterization of the first tuber mustard calmodulin-like gene, BjAAR1, and its functions in responses to abiotic stress and abscisic acid in Arabidopsis

Abstract

The first tuber mustard calmodulin-like (CML) gene BjAAR1 (Brassica juncea var. tumida Tsen et Lee Abiotic stress and Abscisic acid (ABA) Responsive gene 1) was cloned and characterized. The protein encoded by BjAAR1 contains four predicted Ca2+ binding sites (EF-hand motif) and its recombinant protein can bind Ca2+ in vitro. qRT-PCR showed that the expression level of BjAAR1 was rather high in non-swollen stem of tuber mustard and largely reduced in swollen stem. Expression of BjAAR1 enhanced ABA- and stress-induced gene expression in Arabidopsis (Arabidopsis thaliana). Transgenic plants also exhibited hypersensitivity to NaCl, mannitol, and ABA during the seed germination and post-germination stages. ABA biosynthesis inhibitor, norflurazon (NF), rescued hypersensitivity phenotype of transgenic plants to NaCl and mannitol, indicating that BjAAR1 functions in multiple abiotic stresses response through ABA-dependent process.