Biochemical factors contributing to tomato fruit sugar content: a review

Abstract

-Introduction. Consumers and processors value tomatoes with high fruit sugar content; however, most breeding and cultural practices negatively impact this trait. Wild tomato species can accumulate two-to three-fold more fruit sugar than cultivars and are proving to be valuable both as a source of high-sugar loci to broaden the genetic base of currently produced cultivars, and as research material to understand this trait. Synthesis. While cutting-edge genomic approaches have taught us much about fruit phenotypes, it is still important to assess fruit enzyme activities and metabolic fluxes in lines with contrasting fruit sugar accumulation. These metabolic functions are closest to the ripe fruit sugar trait. In this review, we focus our attention on the biochemical pathways, especially starch biosynthesis, that may influence tomato fruit sugars. We try where possible to put this information into a physiological context because together they influence yield. We compare and contrast sugar metabolism in cultivars and wild tomato species and identify factors that may influence differences in their fruit size. Conclusion. Although difficult, we show that it is possible to develop fruit with high horticultural yield and use the breeding line 'Solara' as an example. In addition, we suggest avenues of further investigation to understand the regulation and control of fruit carbohydrate content. USA / Solanum lycopersicum / fruits / sugars / carbohydrate metabolism / carbohydrate contentFacteurs biochimiques contribuant à la teneur en sucre des fruits de tomate : une revue.Résumé -Introduction. Les consommateurs et les industriels apprécient les tomates avec un fort taux en sucres, mais la plupart des pratiques culturales et d'amélioration ont un impact négatif sur ce caractère. Les espèces de tomate sauvage peuvent accumuler 2 ou 3 fois plus de sucres dans le fruit que des cultivars et elles s'avèrent précieuses à la fois comme une source de loci à haute teneur en sucres pour élargir la base génétique des cultivars actuellement produits, et comme matériel de recherche pour comprendre ce caractère. Synthèse. Alors que les approches génomiques de pointe nous ont appris beaucoup sur le phénotype des fruits, il reste important d'évaluer l'activité des enzymes de fruits et les flux métaboliques dans des lignées présentant des situations contrastées d'accumulation de sucres dans les fruits. Ces fonctions métaboliques sont les plus proches du caractère de teneur en sucres dans le fruit mûr. Dans cette synthèse, nous nous sommes focalisés sur les voies biochimiques, en particulier sur la biosynthèse de l'amidon qui peut influencer les sucres dans le fruit des tomates. Nous essayons autant que possible de mettre cette information dans un contexte physiologique car, ensemble, ils influencent le rendement. Nous comparons et mettons en contraste le métabolisme des sucres dans les cultivars et les espèces sauvages de tomate et nous identifions les facteurs qui peuvent influencer des différences de taille des fruits. Conclusio...

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“…TSS is used as a proxy for sugars in fruits, and the values are positively correlated with consumer acceptance. 39 The positive influence of rising K fertilization on TSS and TA was shown in many studies on medium-to large-sized tomatoes. 19,20,23 Also, in the present study, TSS was used as a proxy and increased in all cultivars in both years.…”

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