ALLEVIATION OF COPPER STRESS WITH HOMOBRASSINOSTEROID IN GERMINATING SUNFLOWER ROOTS

Abstract

We investigated potential alleviation effects of homobrassinosteroid (HBR) hormone on sunflower (Helianthus annuus L. cv. TR003) grown under copper (Cu) stress conditions. Seeds were grown under Cu (30 mu M and 40 mu M) and also HBR (2 mu M) treatments to analyse primary root lengths, protein contents, antioxidant system enzymes' activities (superoxide dismutase-SOD and catalase-CAT) and expressions of these enzymes at 48 h and 72 h. When compared to control, Cu applications decreased primary root lengths. On the other hand, HBR application increased primary root lengths of Cu-stressed samples at 48 h and 72 h. Depending on concentration and timing, protein contents and enzyme activities showed varying results in Cu-treated and Cu+HBR-applied samples. In addition to enzyme activities, SOD and CAT expression profiles were also investigated by RT-PCR. Expected band sizes for SOD (309 bp) and CAT (248 bp) were observed in all samples. These results indicate a positive role of HBR on Cu-stressed sunflower for agricultural applications.