Pathogenic and mating type characterization of an uncommon wilt disease of citrus in Tunisia

Résumé

Wilt disease on citrus trees in Tunisia have increased in significance in the northern and center of the country. Trunks and secondary branches of wilted trees were collected and used to isolate the main pathogen and assess pathogenicity on sour orange rootstock. In addition, Mating type (MAT) specific primers were used to assess the mating type of Fusarium oxysporum Schlecht isolates. The distribution of MAT idiomorph may suggest that MAT1-1 is a predominant mating type in the F. oxysporum population. Wilt disease symptoms, recorded at the end of the pathogenicity tests, were associated with reduced plant growth and vigour, with shorter and thinner shoots, and limited number of roots. Principal component analysis (PCA) based on host specificity of isolates (sweet orange and tangerine), geographical origin (CapBon area and Kairouan) and severity index of the isolates showed three groups related to the specific host and origin. The present study has proved essential information on occurrence of mating types of F. oxysporum isolated from citrus.