Effects of Colletotrichum capsici infection on the growth and antioxidative response on defense mechanisms of Capsicum annuum

Abstract

Aims: Capsicum annuum (pepper) is one of the most important crops in the world. It contains an impressive list of phytonutrients that were found to have disease-preventing and health-promoting properties. Today, they are grown widely in many parts of the world as an important commercial crop. However, fungal infection is the main problem that leads to the common pepper disruptive disease, known as the Anthracnose, which lowers the yields of this plant. Therefore, this study was conducted to determine the growth, enzymatic antioxidant specific activities of catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (g-POD) as well as non-enzymatic antioxidants including ascorbic acid, α-tocopherol and carotenoids content in C. annuum as a response to the fungal infections by Colletotrichum capsici. Methodology and results:The assays were conducted at 0, 1, 2, 3, 4 and 5 weeks of fungal treatment periods. The results showed that plant growth (plant height, leaves number, length and width, chlorophyll content) was significantly lower in treated plants compared to controls. The CAT specific activity increased drastically at the early stages of the experiment and decreased thereafter. In contrast, the APX and g-POD specific activity were initially lower, but increased significantly at the later stages of the experiment. For the non-enzymatic antioxidants, the amount of ascorbic acid, αtocopherol and carotenoids content were significantly higher at the first week of treatment and slowly reduced afterwards. Conclusion, significance and impact of study:This study shows that fungal infection inhibited the growth of pepper plants and the enzymatic and non-enzymatic antioxidants worked in concert to fight against the stress caused by the fungal infection, with their different specific roles in removing and reducing the reactive oxygen species in stress condition.