Sugar Metabolism and Fruit Development in the Tomato

Abstract

Sugars are strongly related to fruit yield and quality, playing a critical role in fruit set, growth, ripening, and composition. The tomato (Solanum lycopersicum) is not only an important horticultural crop, but also a useful experimental model plant that can be used to further our understanding of fruit physiology. Therefore, in this review, we consider sugar metabolism and fruit development in the tomato. We begin by discussing how the sugar content of tomato fruit has been successfully increased in a tomato introgression line containing a chromosome segment from a wild relative, and how this has furthered our understanding of the mechanism controlling sugar content. We then outline current knowledge around how sugar sensing and signaling, proton pumps, and auxin affect sugar accumulation and fruit set. The prevention of fruit abscission by auxin, which is transported by PIN auxin efflux carriers and vacuolar proton phyrophosphatase (V-PPase), may retain sucrose transport to the fruit to inhibit programed cell death (PCD) and ensure successful fruit set. There is believed to be a trade-off between fruit sugar content and yield. However, fruit size and yield do not appear to decrease in the tomato introgression line IL8-3 and sucrose-induced repression of translation (SIRT)-engineered tomatoes, which contain higher fruit sugar contents. Future research needs to investigate the factors involved in sugar sensing and signaling, in addition to the sugar metabolic enzymes that have previously been studied for horticultural applications.

NTRC Plays a Crucial Role in Starch Metabolism, Redox Balance, and Tomato Fruit Growth

“…Based on the work in Arabidopsis plants, NTRC has been found to play a major role in detoxification of hydrogen peroxide by providing reductants to 2-Cys Prxs, with NTRC deficiency leading to a strong decrease in the 2-Cys Prxs reduction state in photosynthesizing leaves (Pérez-Ruiz et al, 2006, 2017. Compared to this, our results show that NTRC downregulation leads to a relatively minor decrease in 2-Cys Prxs reduction in developing and ripe tomato fruits (Supplemental Fig.…”

“…2-Cys Prxs are well-known targets of NTRC in Arabidopsis leaves, where they are involved in hydrogen peroxide removal during photosynthesis (Cejudo et al, 2012). Activation of 2-Cys Prxs involves reduction of an intermolecular disulfide bond linking the two subunits of the homodimer (Pérez-Ruiz et al, 2006, 2017. To investigate the role of NTRC in reduction of 2-Cys Prxs in tomato fruits, we assayed the monomer-to-dimer ratio of 2-Cys Prxs in tomato fruit tissues of NTRC-RNAi lines compared to the wild type using nonreducing SDS gels.…”

“…Tomato (Solanum lycopersicum) is an important horticultural crop and major component of the human diet, serving as the primary model system to study fruit physiology and development (Kanayama, 2017). Throughout the fruit developing process, a myriad of changes in color, firmness, taste, and flavor occur that are associated with developmentally regulated metabolic shifts (e.g.…”

“…changes in the levels of carbohydrates, acids, and volatile compounds; . Notably, the abundance of carbohydrates is a key determinant for fruit yield and quality (Kanayama, 2017). During development, immature tomato fruits act as strong sink tissues, into which massive amounts of carbon are imported as Suc from leaf tissues (Osorio and Fernie, 2014).…”

Detection of the tomato allergen Sola l 1 and evaluation of its reactivity after heat and papain treatment

“…Since Japanese individuals consume large amounts of tomatoes, about 9 kg/year (Takada, 2012), the Japanese authorities have established tomatoes as important vegetables for dietary habit (Kanayama, 2017).…”