Biochemical Evaluation of Resistance Responses of Potato to Different Isolates of Alternaria solani

Abstract

The resistance phenotypes of nine potato cultivars to five isolates of Alternaria solani, causal agent of early blight, were studied after inoculation and growth under greenhouse conditions. We identified potato cultivars with both susceptible and resistant phenotypes as well as A. solani isolates with varying degrees of aggressiveness. Two potato cultivars and two pathogen isolates were selected for biochemical analysis of phenol production and peroxidase activity after inoculation. Phenol compounds were evaluated 2, 4, 6, and 8 days after inoculation, while peroxidase activities were monitored daily for 10 days. Native polyacrylamide electrophoresis was used to identify one protein with peroxidase activity in extracts taken 6 days after inoculation. Significantly higher peroxidase activity as well as total phenol content in potato was correlated with resistance in the Iranian potato cultivar Diamond. Variability of responses within the same cultivar to different isolates of A. solani suggests genotypic diversity between isolates that results in phenotypic diversity for pathogen aggressiveness.

Activity of ß-1,3-glucanase and ß-1,4-glucanase in two potato cultivars following challenge by the fungal pathogen Alternaria solani

“…1 ß-1,3- when compared to the susceptible cv. Granula (Shahbazi et al 2010). Although quantification of symptoms was not calculated, the whole plant inoculations done in these experiments confirmed these results, since cv.…”

“…Diamond was correlated with an increase in the amount of total phenols and peroxidase activity (Shahbazi et al 2010). In the present study we have shown that resistance in cv.…”

“…Two isolates of A. solani were recovered from sections of potato leaves with EB lesions. One isolate, named "A", had been characterized previously as being highly aggressive on potato and a second isolate, named "N", was less aggressive (Shahbazi et al 2010). The isolates were maintained on PDA at 20°C for 7 days.…”

Aggressiveness and Fumonisins Production of Fusarium Subglutinans and Fusarium Temperatum on Korean Maize Cultivars

“…An increase in peroxidase due to pathogen challenge has been previously reported [52][53][54]. Interestingly, an increase in peroxidase activity has been associated with an enhanced defense response [55][56][57]. POD is one of the vital antioxidant enzymes involved in the production of reactive oxygen species, which directly kills pathogens via its toxic effect and inhibits pathogen spread through lignin production [58,59].…”

Zebra chip-diseased potato tubers are characterized by increased levels of host phenolics, amino acids, and defense-related proteins

“…chitinases and b-1,3-glucanases) and those that create/maintain environments unsuitable for pathogens (i.e. peroxidases and polyphenol oxidases) [16,18]. Increases in polyphenol oxidase levels would result in increased browning in freshly cut potatoes as the enzyme oxidizes phenolic compounds into brown-colored products.…”