Nitrate content in roots of pepper seedlings exposed to Phytophthora capsici

Abstract

Phytophthora capsici causes root rot, a deadly plant disease. Resistance to diseases is produced by the activation of many defense substances, so knowledge of this natural defense mechanism allows the development of new strategies for disease control. In this study, the response of nitrate (NO3-), which is effective in plant growth and development, in different pepper genotypes exposed to pathogen infection was investigated. For this, resistant and sensitive pepper genotypes were exposed to 102, 103, and 104 zoospore/mL of P. capsici-22 strain and changes in NO3- content were determined from root samples taken on the 2nd, 4th and 6th days after infection. All zoospore concentrations resulted in an overall increase in NO3- content in roots of CM-334 on all days. In KM-181 and SD-8 genotypes, the highest NO3- content was determined on the 6th day of 103 zoospore/mL application. In SD-8 and KM-181 genotypes, a significant decrease in the amount of NO3- was determined on the 4th and 6th days of treatment of 104 zoospore/mL. In these genotypes, a decrease in the amount of NO3- was found with the increase in infection time at high zoospore concentration. When the three pepper genotypes were compared, the highest NO3- content was determined in the resistant CM-334 genotype, which was exposed to 104 zoospore/mL on the 6th day following the infection. In this study, changes in the amount of NO3- in resistant and susceptible pepper genotypes indicated that NO3- may be effective in plant defense against P. capsici-22.