Diversity among Modern Tomato Genotypes at Different Levels in Fresh-Market Breeding

Cultivated tomato has been in existence for about 400 years and breeding activities have been conducted for only eight decades. However, more than 10,000 tomato cultivars have already been developed. Ninety-one tomato genotypes were characterized for twenty-one morphological traits using developmental, vegetative, and fruit traits. Correlation, principal component, and cluster analysis between the traits were carried out. Higher correlations between fruit traits including fruit shape, fruit size, and fruit types were observed. These correlations indicate that specific fruit types require specific traits like branched inflorescence and a greater number of fruits per inflorescence are beneficial only for smaller fruit sizes like cherry and grape tomatoes. Contrastingly, traits like determinate growth habit and fruit maturity are preferred in all fruit types of tomato for better cultivation practices and longer production duration and hence showed lower correlations. Principal component analysis clustered tomato genotypes into three main clusters with multiple subgroups. Similar tomato genotypes were placed into one or more clusters confirming the results from correlation analysis. Involvement of private breeding programs in cultivar development has increased the competition on introgression of novel and desired traits across new cultivars. Understanding the diversity present in modern cultivars and potential traits identification in related wild species can enhance tomato diversity and improve quality and production.