Bolivian tomatoes : genetic diversity, quality traits and value chains

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

Simple Sequence Repeat Markers Reveal Genetic Diversity and Population Structure of Bolivian Wild and Cultivated Tomatoes (Solanum lycopersicum L.)

The western part of South America is a centre of diversity for tomatoes, but genetic diversity studies are lacking for parts of that region, including Bolivia. We used 11 simple sequence repeat (SSR) markers (including seven novel markers) to evaluate genetic diversity and population structure of 28 accessions (four modern cultivars, four advanced lines, nine landraces, 11 wild populations), and to compare their genetic variation against phenotypic traits, geographical origin and altitude. In total, 33 alleles were detected across all loci, with 2-5 alleles per locus. The top three informative SSRs were SLM6-11, LE20592 and TomSatX11-1, with polymorphism information content (PIC) of 0.65, 0.55 and 0.49, respectively. The genetic diversity of Bolivian tomatoes was low, as shown by mean expected heterozygosity (He) of 0.07. Analysis of molecular variance (AMOVA) revealed that 77.3% of the total variation was due to variation between accessions. Significant genetic differentiation was found for geographical origin, cultivation status, fruit shape, fruit size and growth type, each explaining 16-23% of the total variation. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) tree and principal coordinate analysis (PCoA) scatter plot both revealed differentiation between accessions with determinate flowers and accessions with indeterminate flowers, regardless of cultivation status. The genetic profiles of the accessions suggest that the Bolivian tomato gene pool comprises both strictly self-pollinating and open-pollinating genotypes

Genotype and Maturity Stage Affect the Content and Composition of Polyamines in Tomato-Possible Relations to Plant and Human Health

Polyamines (PAs) are molecules affecting several physiological characteristics in all living organisms with cell protective effects, thereby impacting plant and human health. Here, we used HPLC-DAD-ESI-MS to evaluate the content and composition of PAs in eight tomato genotypes over their maturation period, and related the content and composition to other quality traits and possible implications for plant and human health. The tomato genotype, maturity stage and their interactions, significantly affected the content and composition of PAs. Two of the genotypes, 'Huichol' and 'Rio Grande' showed consistently lower levels of PAs than the other evaluated genotypes. The variation in content and composition of PAs among genotypes was found to vary inconsistently over the maturation period. Putrescine content in the different genotypes either did not vary significantly, increased, or showed the lowest level in the middle of the maturation period, while spermidine content decreased or did not show significant variation. The genotypes 'HT36' and 'HT25' showed high levels of PAs during red and green maturity stages, respectively, and can thereby be seen as suitable health promoting red and green candidate tomatoes. Depiction of variation of the PAs creates opportunities for breeding and production of health promoting tomato as a food or food additive

Delving into the Bioactive and Nutritional Compounds in Bolivian Accessions of Tomato (Solanum lycopersicum L.) Fruits: Relationship with Genetic, Phenotypic, and Origin Indicators

Bolivia is one of the centers of origin of tomatoes. As a result, a wide array of tomatoes exists in the country, containing a variety of bioactive compounds that are beneficial for plants and human consumption. Here, we evaluated, by the use of high performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS), 29 accessions from the Bolivian gene bank for content and effects of indicators on polyamines, carotenoids, vitamin C, and their relationships. The content of the bioactive compounds varied significantly (2-500-fold) among accessions with the exception of lutein, spermidine, and spermine. Among the indicators, specifically, the 'genotype group' and the 'locality of origin' had a relationship with the content of carotenoids and vitamin C. However, despite the large variation in bioactive compounds among the genotypes, few determinants of this phenomenon were identified in the present study. Therefore, to distinguish genotypes that produce large amounts of bioactive compounds for breeding purposes or product development, broad-based screening is necessary instead of focusing on indicators or determinants