Variation among the genotypes of tomato for crossability to its wild relatives

Abstract

A inter-specific crossing programme was carried out employing 3 variety/ breeding lines of tomato (Berika, BCT-115 dg and Alisa Craig) which were crossed with its 4 wild relatives (Solanum lycopersicum var. cerasiformae, Solanum pimpinellifolium, Solanum chilense and Solanum peruvianum) in both ways following conventional hybridization method. The number of fruits set and developed up to maturity, which contained viable seeds, determined crossability. In most of the cases, incompatible crosses resulted drop of the flowers, which were cross-pollinated. Solanum lycopersicum x Solanum chilense and Solanum lycopersicum × Solanum peruvianum crosses were not successful. In few crosses of Solanum lycopersicum x Solanum chilense and Solanum lycopersicum × Solanum peruvianum, some under-sized fruits containing no seed developed up to the maturity, which might have happened due to stimulative parthenocarpy. The F1 seeds of the inter-specific hybrids of Solanum lycopersicum × Solanum lycopersicum var. cerasiformae and Solanum pimpinellifolium showed complete viability. However, few seeds in some fruits resulted from the Solanum lycopersicum var. cerasiformae × Solanum lycopersicum and Solanum pimpinellifolium × Solanum lycopersicum crosses did not germinate which amply demonstrated the manifestation of unilateral incongruity. Production of viable hybrids between Solanum lycopersicum × Solanum lycopersicum var. cerasiformae re-established the presumption that part of the Solanum lycopersicum var. cerasiformae was genetically close to the cultivated tomato and Solanum pimpinellifolium belongs to Lycopersicon esculentum complex and close relative of cultivated tomato.