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, ۹۳ 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 ۳۹ SSR primers. Thirty-five polymorphic SSR loci generated a total of ۱۱۸ alleles in the studied germplasm. Number of alleles per locus and effective number of alleles averaged ۳.۳۷ and ۲.۴۷, respectively. Expected heterozygosity of SSRs varied from ۰.۲۲۷ (TMS۲۴) to ۰.۷۷۳ (LEta۰۱۶), averaged ۰.۵۵۸. The mean number of alleles per genomic-SSRs (۳.۶۱) was more than that of EST-SSRs (۲.۶۶). Cluster analysis using Neighbour Joining (NJ) method placed ۹۶ 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 ۲۱ morphological characters, significant (P≤ ۰.۰۵) marker-trait associations were found for ۱۸ characters. Each of SSR loci TC۱۱, TC۹۴۸, and Tom۲۳۶-۲۳۷ 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.

Keywords:

Association mapping , Bayesian clustering , Solanum lycopersicum , SSR.