Genetic Structure and Mixed Linear Model-Based Association Analysis for Morphological Traits in a Collection of Tomato Landraces from Iran and Turkey

To extend the genetic base of Iranian tomato germplasm, 93 landraces were collected from the northwest of Iran and East Anatolian of Turkey, along with three commercial cultivars, and their genetic structure were studied using 39 SSR primers. Thirty-five polymorphic SSR loci generated a total of 118 alleles in the studied germplasm. Number of alleles per locus and effective number of alleles averaged 3.37 and 2.47, respectively. Expected heterozygosity of SSRs varied from 0.227 (TMS24) to 0.773 (LEta016), averaged 0.558. The mean number of alleles per genomic-SSRs (3.61) was more than that of EST-SSRs (2.66). Cluster analysis using Neighbour Joining (NJ) method placed 96 tomato genotypes in eight groups. Little congruence was found between NJ dendrogram and geographical distances. Genetic structure analysis of the germplasm using Bayesian method revealed two sub-populations and separated cherry tomatoes from the other landraces and commercial cultivars. Out of the 21 morphological characters, significant (P≤ 0.05) marker-trait associations were found for 18 characters. Each of SSR loci TC11, TC948, and Tom236-237 was associated with three characters. The genetic variability, structure, and markers associated with the studied traits in the current study can be used for planning tomato breeding programs and future studies.