Sucrose uptake, invertase localization and gene expression in developing fruit of Lycopersicon esculentum and the sucrose-accumulating Lycopersicon hirsutum

Dafna Miron, Marina Petreikov, Nir Carmi, Shmuel Shen, Ilan Levin, David Granot, Eliezer Zamski, Arthur A. Schaffer*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

32 Scopus citations

Abstract

By using immunolocalization and differential extraction methods we show that only apoplastic invertase, but not vacuolar invertase, was present in the mature, sucrose-accumulating L. hirsutum pericarp. In contrast, in the hexose-accumulating L. esculentum fruit, both the apoplastic and vacuolar invertase activities and protein content increase in the mature fruit. Quantitative expression studies of the soluble invertase gene (TIV1) and the apoplastic invertase genes (LINs) showed that only TIV1 gene expression could account for the species and developmental differences of both soluble and insoluble enzyme activity of the pericarp. The expression of the LIN genes encoding for apoplastic tomato invertases was unrelated to the differences in bound enzyme activity and could not account for the rise in bound invertase activity in the mature L. esculentum fruit. Evidence is presented that the bound invertase activity of tomato fruit is also the TIV1 gene product. The presence of apoplastic invertase in the mature sucrose-accumulating L. hirsutum fruit suggests a hydrolysis-resynthesis mechanism of sucrose uptake. In order to test this hypothesis, we studied short- and long-term uptakes of asymmetrically labelled 3H-fructosyl-sucrose accompanied by compartmental analysis of the sugars in attached whole fruits of L. hirsutum and L. esculentum. The results indicate that hydrolysis-resynthesis is slow in the sucrose-accumulating fruit but is not an integral part of an uptake and compartmentation mechanism.

Original languageEnglish
Pages (from-to)35-47
Number of pages13
JournalPhysiologia Plantarum
Volume115
Issue number1
DOIs
StatePublished - 2002

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