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<p style="text-align: justify;"><strong>Aim</strong>: To characterize autochthonous grapevine cultivars from a national germplasm collection, to estimate the phenotypic diversity among and within the cultivars, and to identify the traits that contributed to cultivar heterogeneity.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Seventy major ampelographic descriptors comprising shoot, leaf and fruit traits were investigated to determine the overall degree of polymorphism among 61 autochthonous Tunisian grapevine genotypes. Based on the correlation values obtained between the characters, all descriptors must be considered for the characterization/clustering of the grapes, of which 12 descriptors were identified as the most important. Based on principal component analysis (PCA) and hierarchical cluster analysis (HCA), all cultivars were discriminated and high morphological variation was observed among the accessions. ANOVA demonstrated that most of the morphological variation was found within (89.31 %) rather than between the groups (10.69 %). The Khalt Bouchemma Gabès, Blanc 3 and Blanc 2 genotypes were identified as the barycentres of the groups, representing all the morphological variation observed within autochthonous grapes in Tunisia. These genotypes exhibited all the required characteristics to be introduced into the market and commercialized as table grapes and stand out as the most promising for commercial cultivation.</p><p style="text-align: justify;"><strong>Conclusion</strong>: The detailed ampelographic description presented herein highlighted clear morphological differentiation between Tunisian autochthonous grapevines, investigated for the first time using 70 OIV descriptors, and allowed us for the first time to easily split the Tunisian autochthonous grapevine accessions into wine and table grapes. Numerical analyses showed that the number of morphological traits that are effectively contributing to the characterization of the cultivars could be reduced to 12.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: In this investigation, we highlight the importance of importance of breeding programs, commercialization and evaluation of economically valuable characteristics of the highly diverse autochthonous grapevine cultivars from Tunisia.</p>

This work aimed to find out patterns of virulence\ud variability of a Phoma tracheiphila population of\ud 51 isolates, to determine geographic distribution of Mal\ud Secco disease in citrus orchards of six Mediterranean\ud countries and also to establish correlation between geographic\ud distribution and pathotypic distance of P. tr\ud population structure over our sampling spatial scale.\ud Based on unweighted pair-group method with arithmetic\ud averaging clustering and mean disease rating scores,\ud three distinct virulence groups were identified. The 51\ud isolates were classified into 20 pathotypes. Extensive\ud virulence variability was detected in 51 isolates of P. tr\ud causing MSD of citrus in the Mediterranean basin.\ud Regression plot between pairwise virulence and geographical\ud distance showed that virulence is independent\ud of the geographical origin and that isolates collected\ud from the same country have different degrees of virulence.\ud The lack of significant correlation between virulence\ud and geographic structure confirmed the absence of\ud isolation-by-distance pattern, suggesting non-regular and non-gradual dispersal of the pathogen over this\ud spatial scale

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Studying behaviors of four Italian lemon rootstocks towards Mal Secco leaf infection with the fungus Phoma tracheiphila, isolated in Tunisia in controlled environment, is the aim of this research work. It involves prospection of infected lemons fields in Tunisia, isolation and morphological identification of the fungus, preparation of inoculum and infection of leaves of four rootstocks. Following the artificial inoculation in three assessments after 10, 20 and 30 days post inoculation (dpi) by observing the appearance of disease symptoms, counting the percentage of positive inoculation and determining the average disease intensity according to the leaf empirical scale. All these parameters indicated about the behaviour of the rootstock towards disease in addition to allowing the classification of the four lemon rootstocks according to susceptibility to Mal Secco. Therefore Volkameriana which showed great sensitive behavior was considered as susceptible rootstock. However, Sour Orange showed an intermediate susceptibility to Mal Secco infection and was classified as tolerant rootstock. Nevertheless Flying Dragon and Citrange Troyer were considered as resistant rootstocks after showing a great resistance to the leaf infection by Phoma tracheiphila.