Phenotyping of a diverse tomato collection for postharvest shelf-life.

In all fruit and vegetable crops, reduction in quality during postharvest storage leads to substantial losses of primary production with enormous economic consequences. Also in tomato, fruit shelf-life is an important quality trait. In this study a collection of tomato accessions, consisting of 92 S. lycopersicum landraces and old cultivars and several S. pimpinellifolium accessions, was phenotyped for several shelf-life parameters and biochemical characterization was performed during the postharvest shelf-life of fruit from selected accessions. This collection was selected based on available genotypic data and represents the genetic diversity present in the EU–SOL tomato core collection (Roohanitaziani, 2020). The core collection was grown in a greenhouse, and fruit were harvested at the breaker-turning stage and stored in a controlled climate chamber for 42 d at 18 ⁰C. The shelf-life attributes firmness loss, weight loss, as well as color pigments, were measured once a week and evaluated over time. All three shelf-life-related parameters varied markedly among accessions, resulting in fruit with different shelf-life. The most promising accessions of the first screen were re-grown and analyzed to validate the initial results and six accessions with contrasting shelf-life were selected for metabolite analysis. Fruit were harvested at the breaker stage and stored for 35 d at 18 ⁰C. Samples were taken at weekly intervals and analyzed for volatile compounds, primary metabolites and cell wall polysaccharide monomers. During storage long and short shelf-life accessions showed considerable differences in their content of sugars, such as galactose and polyamines, such as putrescine in their pericarp. The content of three cell wall sugars, galactose, arabinose and galacturonic acid, underwent considerable changes during postharvest storage. The short shelf-life accessions contained a higher amount of arabinose and galactose in their cell wall than other accessions which is indicative of highly branched pectin. This knowledge provides a better understanding of the difference in pectin structure between short and long shelf-life fruit during the ripening process.