Transcriptional profiling of high pigment-2dg tomato mutant links early fruit plastid biogenesis with its overproduction of phytonutrients

Igor Kolotilin, Hinanit Koltai, Yaakov Tadmor, Carmiya Bar-Or, Moshe Reuveni, Ayala Meir, Sahadia Nahon, Haviva Shlomo, Lea Chen, Ilan Levin

Research output: Contribution to journalArticlepeer-review


Phenotypes of the tomato (Solanum lycopersicum) high pigment-2dg (hp-2dg) and hp-2j mutants are caused by lesions in the gene encoding DEETIOLATED1, a negative regulator of light signaling. Homozygous hp-2dg and hp-2j plants display a plethora of distinctive developmental and metabolic phenotypes in comparison to their normal isogenic counterparts. These mutants are, however, best known for the increased levels of carotenoids, primarily lycopene, and other plastid-accumulating functional metabolites. In this study we analyzed the transcriptional alterations in mature-green, breaker, and early red fruits of hp-2dg/hp-2 dg plants in relation to their normal counterparts using microarray technology. Results show that a large portion of the genes that are affected by hp-2dg mutation display a tendency for up- rather than down-regulation. Ontology assignment of these differentially regulated transcripts revealed a consistent up-regulation of transcripts related to chloroplast biogenesis and photosynthesis in hp-2dg mutants throughout fruit ripening. A tendency of up-regulation was also observed in structural genes involved in phytonutrient biosynthesis. However, this up-regulation was not as consistent, positioning plastid biogenesis as an important determinant of phytonutrient overproduction in hp-2dg and possibly other hp mutant fruits. Microscopic observations revealed a highly significant increase in chloroplast size and number in pericarp cells of mature-green hp-2dg/hp-2dg and hp-2j/hp-2 j fruits in comparison to their normal counterparts. This increase could be observed from early stages of fruit development. Therefore, the molecular trigger that drives phytonutrient overproduction in hp-2dg and hp-2j mutant fruits should be initially traced at these early stages.

Original languageEnglish
Pages (from-to)389-401
Number of pages13
JournalPlant Physiology
Issue number2
StatePublished - Oct 2007
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science


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