Pre-Breeding Genetic Diversity Assessment of Tomato (Solanum lycopersicum L.) Cultivars Based on Molecular, Morphological and Physicochemical Parameters

Abstract

Appropriate knowledge of the parental cultivars is a pre-requisite for a successful breeding program. This study characterized fruit yield, quality attributes, and molecular variations of ten tomato cultivars during three consecutive generations under greenhouse conditions. Peto 86, Castle Rock, and Red Star cultivars showed the highest fruit yield (kg/plant), total phenolic compounds (TPC), and sap acidity. Principal component analysis categorized the evaluated fruit yield into three groups based on their quality attributes. A robust positive correlation appeared among traits inside each group. A positive correlation was likewise noticed between the first and the second groups. However, a negative correlation was detected between the first, the second and the third group. Molecular profiling, using seven inter-simple sequence repeat (ISSR) primers, produced 60 loci, including 49 polymorphic loci. The molecular analysis also pinpointed the highest genetic similarity (0.92) between P73 and Moneymaker, while the lowest genetic similarity (0.46) was observed between Castle Rock and Moneymaker. The cultivars P73 and Moneymaker showed the lowest genetic distance (2.24), while the highest genetic distance (5.92) was observed between Super Marmand and Peto86, on the one hand, and between Castle Rock and Moneymaker, on the other hand. The chemical analysis of fruit sap indicated the highest levels of TPC, total flavonoids, anthocyanin, ascorbic acid and total soluble solids in Peto 86 and Castle Rock cultivars. Phylogeny analysis of tomato cultivars based on morphological and molecular attributes indicated four distinct clades. Peto 86, Castle Rock, and Red star cultivars can be recommended for the tomato hybridization breeding programs in the future, with other tomato cultivars as potentially high-yielding parents.