Bolivian tomatoes : genetic diversity, quality traits and value chains

Abstract

Bolivia is considered one of the centres of origin and distribution of tomatoes, and wild relatives harbouring potential genetic diversity and quality traits are preserved in germplasm collections. Tomato is the most commonly grown vegetable world-wide, but in Bolivia, tomatoes are lowyielding and have short shelf-life. This thesis studied genetic diversity of 20 accessions and eight cultivars using 11 simple sequence repeat markers, quality traits and bioactive compounds in fruits of 29 accessions and eight cultivars using HPLC techniques. Fruit quality along the tomato value chain (TVC) was assessed in case studies in four provinces. Genetic diversity was found to be low and party influenced by plant growth type, geographical origin, fruit shape and size, and stage of maturity. A UPGMA tree distributed the 28 accessions into six groups, with separation between indeterminate and determinate plant growth type. Quality traits and polyamines (putrescine, spermidine, spermine) concentrations showed inconsistent variations between six maturity stages studied. At maturity, only two the 29 Bolivian accessions showed significant differences in polyamines concentrations. However, the accessions differed significantly in carotenoids and vitamin C content, but no interaction between polyamines and carotenoids concentrations was observed. Five critical factors within the Bolivian TVC were identified as affecting tomato quality: i) landscape and land access; ii) cultural practices; iii) harvesting process; iv) packing process; and v) transportation system. The new information on Bolivian genetic resources, bioactive compounds and desirable traits presented in this thesis can be used by breeders to develop new cultivars. In a broader perspective, the thesis identified constraints and actors involved in tomato quality determination in a developing country.