Tissue specific localization of pectin-Ca²⁺ cross-linkages and pectin methyl-esterification during fruit ripening in tomato (Solanum lycopersicum)

PLoS One. 2013 Nov 13;8(11):e78949. doi: 10.1371/journal.pone.0078949. eCollection 2013.

Abstract

Fruit ripening is one of the developmental processes accompanying seed development. The tomato is a well-known model for studying fruit ripening and development, and the disassembly of primary cell walls and the middle lamella, such as through pectin de-methylesterified by pectin methylesterase (PE) and depolymerization by polygalacturonase (PG), is generally accepted to be one of the major changes that occur during ripening. Although many reports of the changes in pectin during tomato fruit ripening are focused on the relation to softening of the pericarp or the Blossom-end rot by calcium (Ca²⁺) deficiency disorder, the changes in pectin structure and localization in each tissues during tomato fruit ripening is not well known. In this study, to elucidate the tissue-specific role of pectin during fruit development and ripening, we examined gene expression, the enzymatic activities involved in pectin synthesis and depolymerisation in fruit using biochemical and immunohistochemical analyses, and uronic acids and calcium (Ca)-bound pectin were determined by secondary ion-microprobe mass spectrometry. These results show that changes in pectin properties during fruit development and ripening have tissue-specific patterns. In particular, differential control of pectin methyl-esterification occurs in each tissue. Variations in the cell walls of the pericarp are quite different from that of locular tissues. The Ca-binding pectin and hairy pectin in skin cell layers are important for intercellular and tissue-tissue adhesion. Maintenance of the globular form and softening of tomato fruit may be regulated by the arrangement of pectin structures in each tissue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / metabolism*
  • Carboxylic Ester Hydrolases / genetics
  • Carboxylic Ester Hydrolases / metabolism
  • Cell Wall / metabolism
  • Esterification
  • Fruit / cytology
  • Fruit / growth & development*
  • Fruit / metabolism
  • Gene Expression
  • Organ Specificity
  • Pectins / metabolism*
  • Plant Epidermis / cytology
  • Plant Epidermis / metabolism
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Polygalacturonase / genetics
  • Polygalacturonase / metabolism
  • Solanum lycopersicum / cytology
  • Solanum lycopersicum / growth & development*
  • Solanum lycopersicum / metabolism

Substances

  • Plant Proteins
  • Pectins
  • Carboxylic Ester Hydrolases
  • pectinesterase
  • Polygalacturonase
  • Calcium
  • polygalacturonic acid

Grants and funding

This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas (18075004) and a Grant-in-Aid for Scientific Research on Innovative Areas (24114006). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.