واکاوی نشانگرهای ژنومی مرتبط با مقاومت به Alternaria alternata در گوجه فرنگی، (Solanum lycopersicum L.)

Alternaria alternata, is the dominant species of the causal pathogen of early blight (EB) disease in the Iran, is one of the most important disease, causing significant losses and reducing both the food quantity and quality, thus deteriorates the nutritive values of tomato and other Solanaceae family. Plants infected with early blight develop small black or brown spots, usually about 0.25 to 0.5 inch (6–12 mm) in diameter, on leaves, stems, and fruit. Leaf spots are leathery and often have a concentric ring pattern. They usually appear on older leaves first. In the present study, 35 tomato genotypes for quantitative/qualitative traits including phenotypic (leaf blade width, stem thickness, foliage density, and plant size and correlations with EB resistance) and biomass growth parameters, as well as the extent and structure of genetic variation via Inter Simple Sequence Repeat (ISSR) associated with EB resistance were analyzed. phenotypic comparisons displayed significant differences in leaf blade width (24.95%), stem thickness (30.28%), foliage density (18.88%), and plant size (18.89%), with significant positive correlations with EB resistance (0.18-0.75). Correlation analysis showed that mature fruit size, thickness of fruit pericarp, and leaf type were significantly and negatively correlated with EB resistance (up to -0.41). The susceptible tomato seedlings represented significant reductions in biomass parameters. According to ISSR analysis, the highest resolving power (≥ 0.79) and heterozygosity (≥ 0.24) values revealed the presence of high genetic variability among the tomato genotypes. Bayesian model-based STRUCTURE analysis assembled the genotypes into 4 (ΔK = 4) genetic groups. Combined phenotypic and molecular markers proved to be significantly useful for genetic diversity assessment associated with EB disease resistance.