EFFECT OF LATE BLIGHT CAUSED BY PHYTOPHTHORA INFESTANS ON PHENOLIC CONTENTS OF POTATO ADVANCED LINES/CULTIVARS

Abstract

Phenolic compounds are present in the healthy plants at concentrations sufficient to inhibit growth and sporulation of a pathogen; as a response to infection, their concentration is markedly increased imparting resistance against the invading microorganisms and phytoalexins which are not normally found in healthy plants, are synthesized or increase in amounts after infection. We have tested and found that there was a marked increase in the total phenols in all the 50 lines/cultivars due to late blight appearance as compared to the healthy ones. Results revealed that there was overall increase in the quantity of total phenols in all tested lines after disease appearance and this increase was ranged from 28.1 to 58.6 percent over the healthy plants of the same age group. Maximum increase in phenolic content after disease appearance was 58.6 percent in potato line FD 8-1 while minimum phenol increased in 28.1 percent in line 9619. This increase was also noted in the healthy potato plants which were not infected by the disease but this increase might be due to aging factor, was quite insignificant and unnoticeable. Although the total phenolic content was slightly increased more in those plants which were not diseased than that of healthy plants which were tested at the time when disease did not appear. It is apparent from the above figures that the increase in total phenols was more pronounced in diseased plants as compared to the healthy ones.