Genetic variation among isolates of Alternaria spp. from select Egyptian crops

Abstract

Nine different species of Alternaria represented by 27 isolates were collected from several Egyptian crops and analyzed by RAPD-PCR for genetic diversity using four different RAPD primers. Most isolates produced a distinct pattern of DNA fragments which was used as a measure of the degree of similarity among isolates. Genetic similarity between isolates of A. alternata species-group ranged from 14.8 to 100%, whereas the range was from 14.81 to 96.30% between the other species used in this study. The results indicated considerable genetic variability among Alternaria isolates, even within the same species-group. The phylogenetically related outgroup genus Stemphylium could not be clearly separated using RAPD banding criteria. Of the isolates studied, 62% were pathogenic on tomato fruits. There was no correlation between RAPD cluster analysis and pathogenic abilities of the isolates tested.

Keywords:

• RAPD-PCR
• phylogenetic
• pathogenicity
• tomato

Acknowledgements

The author expresses his gratitude to Professor B. M. Pryor (Department of Plant Pathology, University of Arizona, USA), Prof. Christian P. Kubicek (Institute of Chemical Engineering, Vienna University of Technology) and Dr G. L. Bateman (Rothamsted Research Station, UK) for helpful discussion and critical reading of the manuscript.