Status and Prospects of Lagenaria siceraria (Bottle Gourd) Landraces in Tunisia: A Neglected and Underutilized Resource

Laboratorio de investigación LR21AGR03-Producción y Protección para una Horticultura Sostenible, financiado por el Ministerio de Enseñanza Superior e Investigación Científica de Túnez. Proyecto PID2020-116055RB-C22 I+D+I financiado por MCIN/AEI/10.13039/501100011003 y el proyecto A11-20R financiado por el Gobierno de Aragón.Publishe

Citrullus spp. Germplasm Diversity in Tunisia: An Overview

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Effect of different levels of nitrogen fertilizer on morphological and physiological parameters and nitrates accumulation of lettuce cultivars (Lactuca sativa L.)

The effect of nitrogen fertilizer level on growth and nitrate accumulation was studied in six lettuce cultivars (Lactuca sativa L.): ‘Batavia rouge’, ‘Vitalia’, ‘Great Laks’, ‘Type Beurre’, ‘Romaine’ and ‘Romaine LO3’. Three nitrogen levels: 0, 120 and 240 Kg.ha-1 was applied. During plant growth, agronomical parameters (root weight, fresh and dry matter, head diameter) and physiological parameters (nitrate concentration, chlorophyll fluorescence and sugar content) were evaluated. Results showed significant differences between cultivars and nitrogen treatment for the most agronomical and physiological parameters. The nitrogen treatment affects head weight and nitrate concentration in all cultivars; the cvs ‘Great Laks’ and ‘Type beurre’ accumulated respectively the less and high nitrate concentration. The highest nitrate concentration was recorded in external leaves whereas the lowest concentration was recorded in the central leaves for all cultivars. Furthermore, nitrate distribution and chlorophyll fluorescence on the leaves are closely related. This study revealed also correlation between root nitrate concentration, chlorophyll fluorescence and sugar content for all cultivars. This correlation depended on nitrogen fertilization level and the cultivar used

Melon Germplasm from Tunisia with Immense Breeding Value

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Caracterización de la resistencia a la raza 1.2 de Fusarium oxysporum F.SP. Melonis en melón

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Diversity and Valorization of Local Genetic Resources of Cucurbita in Tunisia

Laboratorio de investigación LR21AGR03-Producción y Protección para una Horticultura Sostenible, financiado por el Ministerio de Enseñanza Superior e Investigación Científica de Túnez. Proyecto PID2020-116055RB-C22 I+D+I financiado por MCIN/AEI/10.13039/501100011003 y el proyecto A11-20R financiado por el Gobierno de Aragón.Publishe

Assessing the Genetic Diversity and Population Structure of a Tunisian Melon (Cucumis melo L.) Collection Using Phenotypic Traits and SSR Molecular Markers

The assessment of genetic diversity and structure of a gene pool is a prerequisite for efficient organization, conservation, and utilization for crop improvement. This study evaluated the genetic diversity and population structure of 24 Tunisian melon accessions, by using 24 phenotypic traits and eight microsatellite (SSR) markers. A considerable phenotypic diversity among accessions was observed for many characters including those related to agronomical performance. All the microsatellites were polymorphic and detected 30 distinct alleles with a moderate (0.43) polymorphic information content. Shannon’s diversity index (0.82) showed a high degree of polymorphism between melon genotypes. The observed heterozygosity (0.10) was less than the expected heterozygosity (0.12), displaying a deficit in heterozygosity because of selection pressure. Molecular clustering and structure analyses based on SSRs separated melon accessions into five groups and showed an intermixed genetic structure between landraces and breeding lines belonging to the different botanical groups. Phenotypic clustering separated the accessions into two main clusters belonging to sweet and non-sweet melon; however, a more precise clustering among inodorus, cantalupensis, and reticulatus subgroups was obtained using combined phenotypic–molecular data. The discordance between phenotypic and molecular data was confirmed by a negative correlation (r = −0.16, p = 0.06) as revealed by the Mantel test. Despite these differences, both markers provided important information about the diversity of the melon germplasm, allowing the correct use of these accessions in future breeding programs. Together they provide a powerful tool for future agricultural and conservation tasks.Publishe

Biochemical Characterization of Local Onion Genotypes (Allium cepa L.) in the Arid Regions of Tunisia

Nineteen Tunisian onion genotypes were characterized based on phytochemical composition, sugar content, and antioxidant activity. The studied onions showed a great diversity on biochemical contents and composition. It seemed that there were differences between genotype categories (local landraces...Publishe

Resistance of Tunisian Melon Landraces to Podosphaera xanthii

Powdery mildew caused by Podosphaera xanthii is among the most threatening fungal diseases affecting melons on the Mediterranean coast. Although the use of genetic resistance is a highly recommended alternative to control this pathogen, many races of this fungus have been described and, therefore, resistance is usually overcome; thus, breeding for resistance to this pathogen is a challenge. Several melon genotypes carrying resistance to powdery mildew have been described but their agronomical and fruit characters are usually far away from the required melon types in many commercial markets. Taking this into consideration, looking for novel sources of resistance in Tunisian landraces is a very convenient step to obtain new resistant melon varieties/hybrids suitable for Mediterranean markets. Several Tunisian melon landraces have been tested against three common races in Mediterranean regions (Race 2, Race 3.5, and Race 5), using phenotypic approaches in two independent experiments (artificial inoculations in a growth chamber and natural conditions of infection in a greenhouse). The results of the artificial inoculations showed that all the tested landraces were susceptible to Race 3.5 and Race 5 and several landraces were resistant to Race 2. Under natural conditions of infection, Race 2 of P. xanthii was the race prevalent in the plot and the resistance of TUN-16, TUN-19, and TUN-25 was confirmed. The found resistances were race-specific and underlie a high genetic influence reflected in the high value of the estimated heritability of 0.86. These resistant landraces should be considered as a potential source of resistance in breeding programs of melons belonging to inodorus and reticulatus groups, but further research is necessary to elucidate the genetic control of the found resistances and to provide useful molecular markers linked to P. xanthii Race 2 resistance.Publishe