THE INFLUENCE OF EXOGENOUS GIBBERELLIC ACID (GA(3)) AND 24-EPIBRASSINOLIDE (24-EpiBL) ON SEED GERMINATION AND THE EXPRESSION OF GENES INVOLVED IN GA AND BR SYNTHESIS/SIGNALLING IN PEPPER (Capsicum annuum L.)

Gibberellins (GAs) and brassinosteroids (BR) are the plant hormones involved in various physiological processes including seed germination. In this study, the effects of exogenous gibberellic acid (GA(3)) and 24-epibrassinolide (24-EpiBL) treatments on the expression of key genes involved in GA and BR synthesis/signalling during seed germination were investigated in pepper (Capsicum annuum L). The expressions of BES1 and BRI1 involved in BR synthesis/signalling pathway as well as GA3OX1 and GA20OX1 associated with gibberellic acid biosynthesis in plants were determined. Exogenous GA3 treatments increased BES1 expression and the highest increase was determined with 10(-8) M BR + 100 mu M GA(3) (P < 0.05). On the contrary, the expression of BRI1 gene was significantly decreased by 10(-8) M BR + 100 mu M GA(3) (P < 0.05). The expression of GA3OX1 gene was induced with BR and GA(3) treatments (P < 0.05). GA20OX1 gene expression was generally higher compared to the expression of GA3OX1 and significantly increased by the GA(3) treatments. Our findings are expected to bring an insight to the influence of BRs during seed germination together with the expression of associated genes.