beta-1,3-Glucanase gene expression in low-hydrated seeds as a mechanism for dormancy release during tobacco after-ripening.
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.
Leubner-Metzger
Gerhard
G
Institut für Biologie II (Botanik/Pflanzenphysiologie), Albert-Ludwigs-Universität Freiburg, Schänzlestr. 1, D-79104 Freiburg i. Br., Germany. gerhard.leubner@biologie.uni-freiburg.de
D015870:Gene Expression; D018525:Germination; D043326:Glucan 1,3-beta-Glucosidase / Q000378:metabolism*; D015151:Immunoblotting; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D014176:Protein Biosynthesis; D012639:Seeds / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D013997:Time Factors; D014026:Nicotiana / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D014158:Transcription, Genetic
D043326:Glucan 1,3-beta-Glucosidase