A barley mutant, 194, was observed to exhibit leaf spot phenotype during the whole growing period. In the current research, the phenotype and antioxidant competence were studied in lesion mimic mutant 194. The plant height was slightly higher in mutant 194. In addition, the leaf spot per plant in mutant 194 was significantly higher than that in wild-type (WT). Antioxidant competence, as indicated by ROS accumulation, antioxidant enzymes activity, and the expression of antioxidant enzyme-encoding genes were also detected in mutant 194. Compared to the WT, mutant 194 displayed relatively higher accumulation of ROS and accompanied by lower activity of some antioxidant enzymes, and the down-regulation of antioxidant enzyme-encoding genes further demonstrated the deterioration of antioxidant competence in mutant 194. The results suggested that the lower antioxidant competence of mutant 194 could accumulate excessive ROS. The excessive ROS could induce PCD and has the potential in the disease resistant in mutant 194.
