Analysis of variation in Alternaria alternata by pathogenicity and RAPD study.

Alternaria alternata were isolated and identified from root, foliage and soil of both wheat and rice crops and their aggressiveness was studied using aggressiveness analysis. Isolates of Alternaria alternata were genetically characterized using RAPD's. The investigations were based on surveys of wheat and rice crops in the rice-wheat cropping areas of Pakistan. The study showed that Alternaria alternata is root rot causing fungi and during root rot aggressiveness analysis the isolates showed higher aggressiveness on rice varieties than on wheat but in foliar aggressiveness the overall number of aggressive isolates was higher on wheat varieties than on rice. In genetic characterization Random Amplified Polymorphism DNA (RAPD) was used to study the polymorphism and genetic variation within the population of Alternaria alternata that established correlation between aggressiveness and genetical characters of fungi. Alternaria alternata tree is constructed based on the pattern of bands. This study highlighted the correlation between morphological, aggressiveness and genetic variations of Alternaria alternata.