A novel strategy to produce sweeter tomato fruits with high sugar contents by fruit-specific expression of a single bZIP transcription factor gene

G. H.M. Sagor, Thomas Berberich, Shun Tanaka, Manabu Nishiyama, Yoshinori Kanayama, Seiji Kojima, Koji Muramoto, Tomonobu Kusano

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Summary: Enhancement of sugar content and sweetness is desirable in some vegetables and in almost all fruits; however, biotechnological methods to increase sugar content are limited. Here, a completely novel methodological approach is presented that produces sweeter tomato fruits but does not have any negative effects on plant growth. Sucrose-induced repression of translation (SIRT), which is mediated by upstream open reading frames (uORFs), was initially reported in Arabidopsis AtbZIP11, a class S basic region leucine zipper (bZIP) transcription factor gene. Here, two AtbZIP11 orthologous genes, SlbZIP1 and SlbZIP2, were identified in tomato (Solanum lycopersicum). SlbZIP1 and SlbZIP2 contained four and three uORFs, respectively, in the cDNA 5'-leader regions. The second uORFs from the 5' cDNA end were conserved and involved in SIRT. Tomato plants were transformed with binary vectors in which only the main open reading frames (ORFs) of SlbZIP1 and SlbZIP2, without the SIRT-responsive uORFs, were placed under the control of the fruit-specific E8 promoter. Growth and morphology of the resulting transgenic tomato plants were comparable to those of wild-type plants. Transgenic fruits were approximately 1.5-fold higher in sugar content (sucrose/glucose/fructose) than nontransgenic tomato fruits. In addition, the levels of several amino acids, such as asparagine and glutamine, were higher in transgenic fruits than in wild-type fruits. This was expected because SlbZIP transactivates the asparagine synthase and proline dehydrogenase genes. This 'sweetening' technology is broadly applicable to other plants that utilize sucrose as a major translocation sugar. >

Original languageEnglish
Pages (from-to)1116-1126
Number of pages11
JournalPlant Biotechnology Journal
Volume14
Issue number4
DOIs
Publication statusPublished - 2016 Apr 1

Keywords

  • Basic region leucine zipper gene
  • Deregulation of translational control
  • Solanum lycopersicum
  • Sucrose
  • Sweetening technology
  • Upstream open reading frame

ASJC Scopus subject areas

  • Biotechnology
  • Agronomy and Crop Science
  • Plant Science

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