ISHS Acta Horticulturae 940: XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on the Challenge for a Sustainable Production, Protection and Consumption of Mediterranean Fruits and Nuts
FUSARIUM SPP. ASSOCIATED TO CITRUS DRY ROOT ROT: AN EMERGING ISSUE FOR MEDITERRANEAN CITRICULTURE |
| Authors: | T. Yaseen, A.M. D'Onghia |
| Keywords: | citrus, dry root rot, Fusarium solani, F. oxysporum, pathogenicity |
| DOI: | 10.17660/ActaHortic.2012.940.89 |
| Abstract:
Fusarium root rot and dry rot are destructive diseases of citrus trees that gradually affect plants under biotic or abiotic stress. Many Fusarium spp. are supposed to be the casual agents of these diseases and their identification could be of an extreme difficulty. In this work, Fusarium spp. were collected from commercial citrus orchards and nurseries in Italy, Tunisia, Greece and Egypt. Three Fusarium species (F. solani, F. oxysporum and F. proliferatum) were identified according to morphological and molecular characterization, thus F. solani and F. oxysporum were the most frequent isolated species and, accordingly, were grouped upon the sequence of β-tubulin and α-Elongation Factor loci into nine clusters. Three pathogenicity characters were assessed: phytotoxicity of fungi excretions, capacity to colonize the surface of citrus host plant and ability to colonize the internal tissues. All trials were carried out on citrus, ‘Carrizo’ citrange. Symptoms of wilting were assessed over two months in phytotoxicity of culture filtrate trial. The results highlighted a significant correlation between phytotoxicity excretions and invasion ability. Nevertheless, no correlation was found between these two measures and the ability to colonize the surface of citrus seedlings. Despite the large variation existing among strains within the species, strains belonging to F. oxysporum showed a higher aggressiveness among all the characters tested, thus confirming the previous results obtained on the pathogenicity of F. oxysporum strains and F. sp. citri. Due to the fact that all the tested isolates were collected from orchards known to have dry root rot symptoms, and according to our finding regarding the higher aggressiveness of F. oxysporum isolates on citrus seedlings, a correlation might be suggested between Fusarium wilt disease affecting citrus seedlings and dry root rot disease observed on scaffold roots of trees in the orchards. | |
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