The Study of Pathogenicity Difference of Pathotypes 4 and 6 A.rabiei the Fungal Cause of Ascochyta Blight on Some Native Cultivars

This study was carried out on the biochemical aspects of chickpea cultivars and the genomic behavior of A. rabiei pathotypes 4 and 6 in four parts: 1) Determining the number of resistant genes in chickpea native cultivars, 2) Comparing the variation of sodium and potassium electrolytes concentrations in noninfected and infected seedling stems of resistant and susceptible cultivars, 3) Studying the effect of potassium deficiency on five differential cultivars by Hoagland nutrient culture, and 4) Using RAPD-PCR method to detect any genomic differences between the two pathotypes used in this study. Eighteen native chickpea cultivars were chosen for this study. The result of the experiments showed that cultivar 1-60-144 possesses the highest number of resistant genes, while the others were either relatively tolerant or susceptible. The reduction of electrolytes concentration in infected cultivar ILC-1929 in comparison to resistant cultivar ILC-5928 is an indication of compatibility between the host plant and the pathogen. Increasing the level of resistance in differential cultivars and appearance of induced resistance as the result of potassium deficiency is due to the production of putrecine diamine. Eighty percent similarity of pathotypes genomic bands by using CG marker and primer 171 showed insufficient primer numbers and the necessity for using complementary methods.