Morphological Characterization and Screening of Solanum Habrochaites Accessions for Late Blight ( Phytophthora Infestans ) Disease Resistance

Late blight ( Phytophthora infestans ), characterized by small water-soaked areas that rapidly enlarge to form purple-brown, oily appearing blotches, is the most destructive fungal disease that continues to stymie worldwide tomato production. Severe outbreaks have been recorded in tomato-growing areas throughout the world in recent years, and the vast majority of commercial tomato cultivars are extremely vulnerable to the late blight infection. The aim of this study was to screen the wild tomato Solanum habrochaites accessions LA1223, LA1353, LA1718, LA1777, LA2156, LA2167, and LA2556 under natural disease pressure conditions to find a possible source of resistance to late blight and also characterized these accessions for various morphological characters. Three S. habrochaites accessions (LA1777, LA2167, and LA2556) were resistant and superior to the susceptible check. With a PDI of 22.29, LA 1777 was shown to have the highest resistance, and as such, it may be used as a donor for late blight resistant tomato pre-breeding programmes in the near future. The success of high crossability (percentage) of some hybrid combinations using LA1777 as a male parent, such as LA3846 × LA1777 (77.77), LA2377 × LA1777 (62.50), and LA3317 × LA1777 (60.00), is encouraging for the development of pre-breeding genetic stocks as well as for the discovery of novel alleles in wild tomato populations. The morphological characterization of seven wild tomato accessions mainly confirms the guidelines of the International Plant Genetic Resources Institute. These accessions and their interspecific crosses showed wide variability in phenotypic and reproductive characters for plant height, flower color, exserted stigma, leaf margin, flowering time, fruit set, and other economic traits that will facilitate breeders in the development of superior tomato cultivars and F 1 hybrids resistant to biotic stresses, as well as differentiate these S. habrochaites accessions for their potential use in genetic enhancement of cultivated tomatoes.