beta-1,3-Glucanase gene expression in low-hydrated seeds as a mechanism for dormancy release during tobacco after-ripening

Plant J. 2005 Jan;41(1):133-45. doi: 10.1111/j.1365-313X.2004.02284.x.

Abstract

An air-dry developmental state with low-hydrated tissues is a characteristic of most plant seeds. Seed dormancy is an intrinsic block of germination and can be released during after-ripening, that is air-dry storage of mature seeds. Both seed-covering layers, testa and endosperm, cause the coat-imposed dormancy of tobacco (Nicotiana tabacum). After-ripening and over-expression of class I beta-1,3-glucanase (betaGlu I) confer maternal effects on testa rupture and dormancy release. Very little is known about the molecular mechanisms of after-ripening and whether gene expression is possible in low-hydrated seeds. Transient, low-level betaGlu I transcription and translation was detected during tobacco seed after-ripening. (1)H NMR 2D micro-imaging showed uneven distribution of proton mobility in seeds. betaGlu I gene expression is associated spatially with the inner testa and temporally with the promotion of testa rupture. Local elevation in moisture content seems to permit local, low-level betaGlu I gene transcription and translation in the maternal tissues of air-dry, low-hydrated seeds. De novo gene expression is therefore proposed to be a novel molecular mechanism for the release of coat-imposed dormancy during oilseed after-ripening.

MeSH terms

  • Gene Expression*
  • Germination
  • Glucan 1,3-beta-Glucosidase / metabolism*
  • Immunoblotting
  • Kinetics
  • Magnetic Resonance Spectroscopy
  • Nicotiana / enzymology*
  • Nicotiana / growth & development
  • Nicotiana / metabolism
  • Protein Biosynthesis
  • Seeds / enzymology
  • Seeds / growth & development
  • Seeds / metabolism*
  • Time Factors
  • Transcription, Genetic

Substances

  • Glucan 1,3-beta-Glucosidase