DWARF overexpression induces alteration in phytohormone homeostasis, development, architecture and carotenoid accumulation in tomato

Plant Biotechnol J. 2016 Mar;14(3):1021-33. doi: 10.1111/pbi.12474. Epub 2015 Sep 18.

Abstract

Brassinosteroids (BRs) play a critical role in plant growth, development and stress response; however, genetic evidence for the BR-mediated integrated regulation of plant growth still remains elusive in crop species. Here, we clarified the function of DWARF (DWF), the key BR biosynthetic gene in tomato, in the regulation of plant growth and architecture, phytohormone homeostasis and fruit development by comparing wild type, d^(im), a weak allele mutant impaired in DWF, and DWF-overexpressing plants in tomato. Results showed that increases in DWF transcripts and endogenous BR level resulted in improved germination, lateral root development, CO2 assimilation and eventually plant growth as characterized by slender and compact plant architecture. However, an increase in DWF transcript down-regulated the accumulation of gibberellin, which was associated with decreases in leaf size and thickness. BRs positively regulated lateral bud outgrowth, which was associated with decreased transcript of Aux/IAA3, and the ethylene-dependent petiole bending and fruit ripening. Notably, overexpression of DWF did not significantly alter fruit yield per plant; however, increases by 57.4% and 95.3% might be estimated in fruit yield per square metre in two transgenic lines due to their compact architecture. Significantly, BR level was positively related with the carotenoid accumulation in the fruits. Taken together, our results demonstrate that BRs are actively involved in the regulation of multiple developmental processes relating to agronomical important traits.

Keywords: brassinosteroids; cell enlargement; ethylene; gibberellin; leaf bending; photosynthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brassinosteroids / biosynthesis
  • Brassinosteroids / metabolism
  • Carotenoids / metabolism
  • Ethylenes / metabolism
  • Fruit / drug effects
  • Fruit / growth & development
  • Gene Expression Regulation, Plant / drug effects
  • Germination / drug effects
  • Germination / genetics
  • Homeostasis / drug effects*
  • Lycopersicon esculentum / anatomy & histology*
  • Lycopersicon esculentum / metabolism*
  • Photosynthesis / drug effects
  • Plant Growth Regulators / pharmacology*
  • Plant Leaves / drug effects
  • Plant Leaves / physiology
  • Plant Proteins / genetics
  • Plant Proteins / metabolism*
  • Plant Roots / drug effects
  • Plant Roots / growth & development
  • Plants, Genetically Modified
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Seeds / drug effects
  • Seeds / genetics
  • Seeds / growth & development

Substances

  • Brassinosteroids
  • Ethylenes
  • Plant Growth Regulators
  • Plant Proteins
  • RNA, Messenger
  • Carotenoids
  • ethylene