Modification of Carbohydrate Content in Developing Tomato Fruit

Schaffer, Arthur A.; Petreikov, Marina; Miron, Daphne; Fogelman, Miriam; Spiegelman, Moshe; Bnei-Moshe, Zecharia; Shen, Shmuel; Granot, David; Hadas, Rivka; Dai, Nir; Bar, Maya; Friedman, Michael; Pilowsky, M.; Gilboa, N.; Chen, Leah

doi:10.21273/hortsci.32.3.551e

Cited by 10 publications

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“…Starch accumulation may be enhanced by an increase of the main enzyme activity [ADP glucose pyrophosphorylase (ADPGppase)] or of the level of synthesis of the substrate (glucose 6P) ( Robinson et al , 1988 ; Nguyen-Quoc and Foyer, 2001 ); it is also triggered by the amount of sucrose unloaded in the fruit ( D'Aoust et al , 1999 ; N'Tchobo et al , 1999 ), which is higher in cherry tomatoes than in large-fruited cultivars ( Islam and Khan, 2001 ). The presence of the apoplastic cell wall invertase gene lin5 ( Fridman and Zamir, 2003 ; Fridman et al , 2004 ) and of a hexose transporter ( Causse et al , 2004 ), together with the absence of a gene regulating the ADPGppase on chromosome 9 ( Schaffer et al , 2000 ), supports the hypothesis that high starch accumulation in L9 was stimulated by the higher sucrose unloading, and hexose transport within the cells (Ruan et al ., 1995, 1997; Ho, 1996 ; Schaffer et al , 1999 ), as observed in an other study ( Li et al , 2002 ). However, the fact that high starch, but not high soluble contents, were recovered in Lx suggested the involvement of several levels of regulation.…”

Section: Discussionsupporting

confidence: 81%

Identification of growth processes involved in QTLs for tomato fruit size and composition

Bertin

Causse

Brunel

et al. 2008

Journal of Experimental Botany

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Many quantitative trait loci (QTLs) for quality traits have been located on the tomato genetic map, but introgression of favourable wild alleles into large fruited species is hampered by co-localizations of QTLs with antagonist effects. The aim of this study was to assess the growth processes controlled by the main QTLs for fruit size and composition. Four nearly isogenic lines (NILs) derived from an intraspecific cross between a tasty cherry tomato (Cervil) and a normal-tasting large fruit tomato (Levovil) were studied. The lines carried one (L2, L4, and L9) or five (Lx) introgressions from Cervil on chromosomes 1, 2, 4, and 9. QTLs for fruit size could be mainly associated with cell division processes in L2 and L9, whereas cell expansion was rather homogeneous among the genotypes, except Cervil for which the low expansion rate was attributed to low cell plasticity. The link between endoreduplication and fruit size remained unclear, as cell or fruit sizes were positively correlated with the cell DNA content, but not with the endoreduplication factor. QTLs for fruit composition reflected differences in water accumulation rather than in sugar accumulation, except in L9 for which the up-regulation of sucrose unloading and hexose transport and/or starch synthesis was suggested. This may explain the increased amount of carbon allocated to cell structures in L9, which could be related to a QTL for fruit texture. In Lx, these effects were attenuated, except on fruit size and cell division. Finally, the region on top of chromosome 9 may control size and composition attributes in tomato, by a combination of QTL effects on cell division, cell wall synthesis, and carbon import and metabolism.

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Section: Discussionsupporting

confidence: 81%

Identification of growth processes involved in QTLs for tomato fruit size and composition

Bertin

Causse

Brunel

et al. 2008

Journal of Experimental Botany

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“…Schaffer et al . (1999) and Suzuki et al . (2001) considered that PGI was unlikely to be responsible for the regulation of fructose levels in these two species.…”

Section: Discussionmentioning

confidence: 96%

Application of a SUGAR model to analyse sugar accumulation in peach cultivars that differ in glucose–fructose ratio

Quilot²,

Génard³

et al. 2011

J. Agric. Sci.

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A SUGAR model, which was established to predict the partitioning of carbon into sucrose, glucose, fructose and sorbitol in fruit mesocarp of peach cultivars (Prunus persica (L.) Batch) with normal glucose: fructose ratio (G:F) of 0·8-1·5, was evaluated and extended for peach cultivars with a high G:F ratio of 1·5-7·8. The extended model (SUGARb) is more generic and assumes a high G:F ratio to be due to preferential transformation of sorbitol into glucose, preferential utilization of fructose or preferential conversion of fructose into glucose. The simulated seasonal variations in sugars via the SUGARb-model-matched experimental data for three normal and three high G:F cultivars well, and accurately exhibited G:F ratio characteristics. The relative rates of sucrose transformation into glucose and fructose differed according to cultivar but not according to G:F status. Compared with hexosephosphate interconversion, a lower production rate of fructose than glucose from sorbitol, and/or a higher utilization rate of fructose than that of glucose might be preferential alternatives for forming high G:F ratios in the high G:F cultivars studied in the present study, which is discussed in the light of recent results on enzyme activities.

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“…Solanum habrochaites fruit primarily accumulates the disaccharide sucrose, with relatively low levels of hexose (Miron and Schaffer, 1991); however, results from over 50 years ago indicated that its low hexose content is also characterized by an unusually high ratio of fructose to glucose (Davies, 1966). The trait of high fructose to glucose is independently inherited from that of sucrose accumulation (Stommell and Haynes, 1993;Schaffer et al, 1998), and hexose-accumulating tomatoes with an increased ratio of fructose to glucose can be developed (Schaffer et al, 1998). The trait was found to be determined by a major gene, which we termed Fgr (fructose to glucose ratio), and breeding lines of tomato harboring the S. habrochaites Fgr allele (Fgr H ) had a significantly increased level of fructose, accompanied by a decrease in the level of glucose (Levin et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

“…Surprisingly, the inedible, wild species of tomato have served as a source of genetic variability for improving fruit sugar levels and taste in cultivated tomatoes. For example, the trait of sucrose accumulation, determined by the TIV gene, has been introgressed from Solanum chmiliewskii (Chetelat et al, 1995) and S. habrochaites (Hadas et al, 1995;Schaffer et al, 1998), leading to sucrose-accumulating tomatoes. Genetic traits of increased total hexose levels were introduced from Solanum pennellii (LIN5; Fridman et al, 2000) and S. habrochaites (AGPL1; Petreikov et al, 2006Petreikov et al, , 2009).…”

Section: Introductionmentioning

confidence: 99%

Natural genetic variation for expression of a SWEET transporter among wild species of Solanum lycopersicum (tomato) determines the hexose composition of ripening tomato fruit

et al. 2018

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The sugar content of Solanum lycopersicum (tomato) fruit is a primary determinant of taste and quality. Cultivated tomato fruit are characterized by near-equimolar levels of the hexoses glucose and fructose, derived from the hydrolysis of translocated sucrose. As fructose is perceived as approximately twice as sweet as glucose, increasing its concentration at the expense of glucose can improve tomato fruit taste. Introgressions of the Fgr allele from the wild species Solanum habrochaites (LA1777) into cultivated tomato increased the fructose-to-glucose ratio of the ripe fruit by reducing glucose levels and concomitantly increasing fructose levels. In order to identify the function of the Fgr gene, we combined a fine-mapping strategy with RNAseq differential expression analysis of near-isogenic tomato lines. The results indicated that a SWEET protein was strongly upregulated in the lines with a high fructose-to-glucose ratio. Overexpressing the SWEET protein in transgenic tomato plants dramatically reduced the glucose levels and increased the fructose : glucose ratio in the developing fruit, thereby proving the function of the protein. The SWEET protein was localized to the plasma membrane and expression of the SlFgr gene in a yeast line lacking native hexose transporters complemented growth with glucose, but not with fructose. These results indicate that the SlFgr gene encodes a plasma membrane-localized glucose efflux transporter of the SWEET family, the overexpression of which reduces glucose levels and may allow for increased fructose levels. This article identifies the function of the tomato Fgr gene as a SWEET transporter, the upregulation of which leads to a modified sugar accumulation pattern in the fleshy fruit. The results point to the potential of the inedible wild species to improve fruit sugar accumulation via sugar transport mechanisms.

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Modification of Carbohydrate Content in Developing Tomato Fruit

Cited by 10 publications

References 0 publications

Identification of growth processes involved in QTLs for tomato fruit size and composition

Identification of growth processes involved in QTLs for tomato fruit size and composition

Application of a SUGAR model to analyse sugar accumulation in peach cultivars that differ in glucose–fructose ratio

Natural genetic variation for expression of a SWEET transporter among wild species of Solanum lycopersicum (tomato) determines the hexose composition of ripening tomato fruit

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