Isolation and characterization of gene encoding G protein α subunit protein responsive to plant hormones and abiotic stresses in Brassica napus

G protein plays an important role in signal pathways and involved in various signal transduction systems in plant. A full-length cDNA encoding a putative G protein alpha subunit (G alpha), designated as BnGA1, was isolated from Brassica napus. The expression of BnGA1 in different B. napus tissues and developmental stags was analyzed using real-time PCR. The results showed that BnGA1 expressed was high in root, cotyledon and shoot apex. Stage expression pattern analysis revealed that BnGA1 expressed strongly at the 7th day, the bolting stage and fruiting stage. In addition, the expression of BnGA1 was analyzed under different concentrations of four plant hormones. The expression of BnGA1 was significantly induced by the high concentrations of abscisic acid (ABA) and brassinosteroid (BR). The expression of BnGA1 was also induced by low gibberellins acid 3 (GA(3)) concentrations and higher GA(3) concentrations inhibit the expression of BnGA1. However, the expression of BnGA1 did not significantly regulated by exogenous indole-3-acetic acid (IAA). Moreover, the expression of BnGA1 under different abiotic stresses was analyzed at different time points. The BnGA1 was up-regulated in salt and drought stress and down-regulated in heat and cold stress. These expression results suggested that BnGA1 play an important role in plant hormones signal pathways and BnGA1 may be involved in plant defense system against environmental stresses in B. napus.