Genetic divergence and combining ability of mini tomato (Solanum lycopersicum var. cerasiforme) lines from different sources

ABSTRACT The objectives were to evaluate genetic divergence in 59 Solanum lycopersicum var. cerasiforme lines correlating with the country of origin, and to estimate the combining ability of 13 selected lines based on high soluble solids contents (°Brix). The DNA of the 59 lines was amplified using nine inter-simple sequence repeat (ISSR) primers. Shannon’s diversity index (I = 0.47) and Nei’s genetic diversity (h = 0.30) indicated high genetic diversity. Genetic differentiation coefficient (GST) = 0.035 suggested low genetic differentiation between populations and analysis of molecular variance (AMOVA) showed that high variability was not confined to any single country of origin. Principal coordinates analysis (PCoA) clustered the genotypes into three main groups, and a dendrogram confirmed no apparent relationship between the origin and the genetic profiles of the lines. Genetic classification of the mini tomato lines based on their country of origin is not feasible using ISSR markers. The 78 hybrids obtained from the crosses among the 13 selected lines were evaluated in a complete diallel scheme over two seasons, considering the number of bunches, number of fruits per bunch, average fruit weight, fruit length and width, peduncular scar, °Brix, productive cycle, and yield. Average fruit weight and yield were the traits that most influenced the genetic diversity of these 13 parental lines. Based on general combining ability (GCA) we identified lines with good performance for each trait, while specific combining ability (SCA) revealed crosses that exhibited outstanding performance. Promising lines and hybrids were selected for mini tomato breeding program advancement.