Morphological and Molecular Marker Based Screening of Tomato Genotypes (Solanum Lycopersicum L.) for Ty-2 Gene

Abstract

Tomato (Solanum lycopersicum L.) is a widely cultivated solanaceous vegetable crop worldwide due to its economic value. However, its growth is significantly impacted by the tomato leaf curl virus disease (ToLCV/TYLCV), which is caused by begomoviruses and transmitted by the whitefly (Bemisia tabaci). To address this issue, a study was conducted to identify tomato genotypes with favourable horticultural traits and strong, long-lasting resistance against ToLCV/TYLCV. Twenty- five diverse tomato genotypes, each carrying different variations of the Ty-2 gene, were carefully evaluated through both phenotypic and genotypic screening methods. The aim was to identify genotypes that not only exhibit desirable horticultural characteristics but also possess robust resistance against the ToLCV/TYLCV disease and morphological and molecular marker-based diversity were done. Morphological data pertaining to different horticultural traits and disease symptoms, including the percentage of disease incidence (PDI) and disease severity caused by ToLCV, were documented during the mature stage of tomato plants in a field setting. Simultaneously, the validation of the Ty-2 gene was performed in a molecular laboratory. This process involved verifying the presence and functionality of the Ty-2 gene in the selected tomato genotypes, ensuring its role in conferring resistance against ToLCV. In both seasons, there was sufficient variation for all of the features. Among all characters all had high phenotypic and genotypic coefficients of variation, heritability and genetic advance as percent mean. Therefore, it was concluded that direct selection would be the best method for developing these characteristics. The number of fruits per plant and average fruit weight may be used as the best selection indicators due to their great direct contribution and high correlation with yield/plant. The highest inter cluster distance was recorded between Cluster I and Cluster II and Cluster II and Cluster IV (5.789) revealing that the genotypes included in this cluster are very diverse and were due to both natural and artificial selection forces among the genotypes. The genotypes Arka Rakshak F1, Arka Samrat F1, VRT 70, VRT 52 and VRT 24-1 were found superior for yield and yield contributing attributes for the both rabi season. Among the 25 genotypes 11 genotype, namely VRT 67, VRT 52, VRT 66, Arka Rakshak, VRT 16, VRT 78, VRT 58, Arka Samrat, VRT 17, Punjab Ratta, VRT 62, showed resistant for Ty-2gene, while 3 genotypes, namely, VRT 27, Pant T-3, Punjab Gaurav showed susceptibility for Ty-2gene