Morphological and Molecular Characterization of Alternaria sect. Ulocladioides/Ulocladium Isolated from Citrus Fruits in Upper Egypt

Abstract

Citrus is the most important crop in Upper Egypt. 150 infected samples were collected from citrus samples (Navel orange, Tangerine and Lemon) in Upper Egypt, 50 samples from each fruit. Twenty-two isolates representing three species of Alternaria belong to A. sect. Ulocladioides and A. sect. Ulocladium were isolated on dichloran chloramphenicol- peptone agar (DCPA) medium at 27°C. Tangerine samples were more contaminated with Alternaria followed by Navel orange and no Alternaria species appeared from Lemon samples. Based on the Alt a1 the phylogenetic analysis identified the isolates as Alternaria atra, Alternaria botrytis and Alternaria oudemansii. The pathogenicity of the isolates was tested by inoculation of healthy navel orange, the resulted data showed that all tested isolates were pathogenic to healthy navel orange with different degrees ranged from 31.5±1 - 20±1 mm and A. oudemansii had a low virulent effect. The mycotoxins ability of tested isolates indicated that about 83% of the isolates were TeA toxin producers with amount ranged from 1.54 - 18.47 ug/ml.