Antioxidant enzyme activities in Allium species and their cultivars under water stress

We compared the enzymatic antioxidative defence mechanisms of some regional subspecies of Allium (A. cepa L., A. ascalonicum auct. hort., A. sativum L.) cultivated mainly in the western regions of Romania, and two modern Hungarian climate resistant F, hybrids. The variability in the activities of antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione reductase (GR) and glutathione S-transferase (GST) and their changes under soil moisture stress were investigated. I-week-long water stress revealed that among three Allium species, relative water content decreased only in A. ascalonicum leaves (up to 16%). Unlike root enzymes, the activities of the shoot enzymes, especially POD, GR and GST showed a stronger correlation with the water content of the leaves after one week of water withdrawal; regression coefficients (R-2) were 0.359, 0.518 and 0.279, respectively. The ancient populations with elevated (or highly inducible) antioxidant enzyme activities may be interesting for further research and for breeding of new Allium varieties.