BIC1 And BIC2 Are Involved In The Regulation Of ABA Response In Arabidopsis

Absciatic acid(ABA)is one of the five classical plant hormones,regulates many aspects of plant growth and development,such as plant embryogenesis,seed germination and dormancy,vegetative growth and fruit maturation.Moreover,it plays a critical regulatory role in the regulationof plant response to biological and abiotic stresses.It has been reported that BIC1 and BIC2 are involved in the photoactivation and deactivation of cryptochrome CRY1 and CRY2 in Arabidopsis.However,from a transcriptome analysis,we found that the expressions of BIC1 and BIC2 were regulated by ABA.This study reports the roles of BIC1 and BIC2 in regulating ABA response in Arabidopsis.The expression of BIC1 and BIC2 in response to ABA was detected by RT-PCR,and results confirmed that BIC1 and BIC2 are ABA responsive genes.In addition,RT-PCR was also used to detect the expression patterns of BIC1 and BIC2.We found that BIC1 had relatively high expression levels in stem,flower and silique ereas.BIC2 had relatively high expression in root,stem,rosette,stem,flower and silique.Constructs expressing fusion proteins of GFP-BIC1 and GFP-BIC2 were used to examine subcelural localization of BIC1 and BIC2,and we found they are nucler proteins.Transient transfection of GD-BIC1 and GD-BIC2 in protoplast showed both BIC1 and BIC2 are transcriptional active,but BIC2 showed a higher transcriptional activity.In order to explore the roles of BIC1 and BIC2 in the regulation of plant response to ABA,we isolated a T-DNA insertation mutant for each of the two genes,namely bic1-1 and bic2-1.Meanwhile,we generated another mutant for each gene,i.e.,bic1-2 and bic2-2 by using CRISPR/Cas9 genome editing technique.We also generated double mutants bic1bic2-1 and bic1bic2-2 by using CRISPR/Cas9.By generating overexpression vectors for BIC1 and BIC2 and used for plant transformation,we also generated overexpression plants for these genes.The results showed that BIC1 and BIC2 overexpressing transgenic plants were more sensitive to ABA,indicating that BIC1 and BIC2 positively regulate the response of plant ABA.