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Molecular Analyses of Colletotrichum Species from Almond and Other Fruits

First, fourth, and fifth authors: Department of Plant Pathology, ARO, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; second author: Department of Soil Sciences, ARO, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel; and third author: Department of Plant Pathology and Microbiology, The Hebrew University of Jerusalem, Faculty of Agriculture, Food and Environmental Quality Sciences, Rehovot 76100, Israel

Isolates of Colletotrichum spp. from almond, avocado, and strawberry from Israel and isolates of the pink subpopulation from almond from the United States were characterized by various molecular methods and compared with morphological identification. Taxon-specific primer analysis grouped the avocado isolates within the species C. gloeosporioides and the U.S. almond and Israeli strawberry isolates within the species C. acutatum. However, the Israeli almond isolates, previously identified morphologically as C. gloeosporioides, reacted with C. acutatum-specific primers. Arbitrarily primed polymerase chain reaction and A+T-rich DNA analyses determined that each population from almond and strawberry was distinct and clonal. Sequence analysis of the complete internal transcribed spacer (ITS) region (ITS 1--5.8S--ITS 2) revealed a similarity of between 97.03 and 98.72% among almond isolates from Israel, C. acutatum almond isolates from the United States, and C. acutatum strawberry isolates from Israel. Similarity of the above populations to that of C. gloeosporioides of avocado was between 92.42 and 92.86%. DNA sequence analysis of the entire ITS region supported the phylogeny inferred from the ITS 1 tree of 14 different Colletotrichum species. Although morphological criteria indicated that the Israeli isolates from almond are unique, this population was grouped within the C. acutatum species according to molecular analyses.

Additional keywords: Glomerella, rDNA (ITS 1 to ITS 2) sequence, species-specific primers.