The role of Cleavage and Polyadenylation Specificity Factor (CPSF) gene in Brassinosteroid signal transduction in Arabidopsis thaliana

Abstract

Brassinosteroids (BRs), a class of plant steroid hormones, are ubiquitously involved in regulating normal growth processes. The hormone controls flowering, leaves shape, color, male fertility, cell elongation and vascular differentiation. Genetic assessments explored a number of genes showing their role in BRs response pathways. We have screened the activation tagged mutants that have severed growth defects and respond to a BRs biosynthetic inhibitor, brassinazole (Brz). Brassinazole is an inhibitor of active BRs that develops characteristic light grown phenotype under dark. The mutant shows taller, dark green, late flowering, short petioles, short and/or curved siliques had fewer seeds with low germination. The mutant had hard texture in maturity. Fruiting was appeared successionally in the mutant having various stages of maturity. TAIL-PCR, genotyping PCR and segregation ratio of T2 plants revealed a single T-DNA insertion at the first exon of Cleavage Polyadenylation Specific Factor (CPSF) gene in chromosome III that encodes a subunit C-terminal domain-containing protein; similar to DDB1A (UV-damaged DNA-binding protein 1A) in Arabidopsis thaliana. To see response of the gene with other BR related mutants, we crossed the mutant between det2, a BRs biosynthetic mutant, bin2 and bes1D. We also observed the sense and antisense expression effect of the gene in phenotype. Real Time RT-PCR results showed that there was no alteration in expression level of neighboring genes of the T-DNA insertion. Hypocotyls length of Brz-treated mutant seedlings under dark measured nearly two fold longer than wild type Columbia 0 revealing involvement of cpsf in BRs signal transduction. The crossing results reflected that the T-DNA insertion mutation of CPSF related to BR perception and it regulate normal growth process through involving in BRs signaling pathways in Arabidopsis. Also cpsf knockdown or overexpression creates defective siliques and might develop lethality in Arabidopsis.