Embryo rescue of inter-specific hybrid of Solanum lycopersicum × S. neorickii

Abstract

The tomato wild accession LA2325 (Solanum neorickkii) shows strong resistance to early blight (EB) caused by Alternaria solani. To study genetics of the resistance and to transfer the resistance to cultivated tomato, crosses were made between accessionLA2325 and highly susceptible genotype Hawaii 3998. The crosses yielded no viable seeds. It is well known that fertilization barriers like incompatibility and embryo abortion come in the way of development of inter-specific hybrid. This hampers introgression of resistance to cultivated tomato. In the subsequent season, pollen from LA2325was used to pollinate the susceptible cultivar and pro-embryos were collected from developing fruits 39-49 days after pollination. Rescue of immature embryos was done on Murashige and Skoog medium (MS-medium). Pro-embryos from fruits of 42 - 44 days after pollination gave good response. A total of ten plants were regenerated. Developed seedlings were hardened and shifted to green house. The hybridity of the rescued plants was confirmed by comparing the morphological characters of the interspecific hybrid and parents. Further, cleaved amplified polymorphic sequences (CAPS) marker was also used for verifying the hybridity. The embryo rescued inter-specific hybrid is being used as a resource for generating different genetic populations to study the genetics of the EB resistance and to transfer the resistance to cultivated tomato.