Fruit-localized phytochromes regulate lycopene accumulation independently of ethylene production in tomato

Plant Physiol. 2000 May;123(1):363-70. doi: 10.1104/pp.123.1.363.

Abstract

We show that phytochromes modulate differentially various facets of light-induced ripening of tomato fruit (Solanum lycopersicum L.). Northern analysis demonstrated that phytochrome A mRNA in fruit accumulates 11.4-fold during ripening. Spectroradiometric measurement of pericarp tissues revealed that the red to far-red ratio increases 4-fold in pericarp tissues during ripening from the immature-green to the red-ripe stage. Brief red-light treatment of harvested mature-green fruit stimulated lycopene accumulation 2. 3-fold during fruit development. This red-light-induced lycopene accumulation was reversed by subsequent treatment with far-red light, establishing that light-induced accumulation of lycopene in tomato is regulated by fruit-localized phytochromes. Red-light and red-light/far-red-light treatments during ripening did not influence ethylene production, indicating that the biosynthesis of this ripening hormone in these tissues is not regulated by fruit-localized phytochromes. Compression analysis of fruit treated with red light or red/far-red light indicated that phytochromes do not regulate the rate or extent of pericarp softening during ripening. Moreover, treatments with red or red/far-red light did not alter the concentrations of citrate, malate, fructose, glucose, or sucrose in fruit. These results are consistent with two conclusions: (a) fruit-localized phytochromes regulate light-induced lycopene accumulation independently of ethylene biosynthesis; and (b) fruit-localized phytochromes are not global regulators of ripening, but instead regulate one or more specific components of this developmental process.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Carotenoids / metabolism*
  • Ethylenes / biosynthesis*
  • Fruit / metabolism*
  • Gene Expression Regulation, Plant
  • Lycopene
  • Phytochrome / genetics
  • Phytochrome / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Solanum lycopersicum / metabolism*

Substances

  • Ethylenes
  • RNA, Messenger
  • Phytochrome
  • Carotenoids
  • ethylene
  • Lycopene