Response of the heme oxygenase of soybean nodules to drought stress

BARCIA, ROBERTO; SANTA-CRUZ, DIEGO M.; BALESTRASSE, KARINA B.; TOMARO, MARÍA L.

Miami Beach, Florida, USA

Congreso; Heme Oxygenases in Biology and Medicine, 6th International Congress on Heme Oxygenases; 2009

Drought stress is among the most serious challenges to crop production worldwide. Upon exposure of plants to drought conditions, many stress-related genes are induced and their products are thought to function as cellular protectors of stress-induced damage. The aim of this study was to evaluate whether there is a link between drought stress and soybean plants nodules heme oxygenase (HO-1) behavior. To this purpose, soybean plants were inoculated with Bradyrhizobium japonicum. After 30 days growth, they were subjected to drought for 5 days. Under this condition no difference was found in TBARS content respect to controls. Nevertheless, an increase of catalase (CAT) activity (60%) was observed. No induction of HO-1 gene expression was detected, as demonstrated by RT-PCR analysis. To further investigate the effect of drought, experiments were performed with plants exposed to this stress for 10 days. Under this condition, there is an augmentation in TBARS levels (45%) and CAT activity (20%) respect to controls. Besides, HO-1 gene expression was enhanced by 40%. Plants were then recovered for 6 days employing Hoagland solution. Results obtained showed that no production of TBARS occurred, whereas an increase in CAT activity (30%) and HO-1 gene expression (35%) were evidenced. These results let us assume that HO-1 gene expression response to 10 days drought treatment in an attempt to cope with oxidative stress generation, but this purpose only was obtained when plants were subjected to stress recovered. In this situation, the increase in HO-1 gene expression together with CAT activity enhanced was responsible of the alleviation of drought-induced oxidative stress.