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

Abstract

SummaryAn 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 b-1,3-glucanase (bGlu 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 bGlu 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. bGlu 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 bGlu 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.

ROS Signaling in Seed Dormancy Alleviation

“…As for proteome oxidation, it is worth to note that the effects of MV and cyanide on gene expression share some homology, highlighting again that their mechanisms of action are probably very close, involving ROS signaling. We also observed that 11 out of 78 TDF were found in nondormant seeds after after-ripening (data not shown) showing that changes in gene expression may occur in the dry state, as already suggested by Leubner-Metzer, 17 Bove et al 13 and Leymarie et al 15…”

The Time Required for Dormancy Release in Arabidopsis Is Determined by DELAY OF GERMINATION1 Protein Levels in Freshly Harvested Seeds

“…These were the endosperm-specific promoters Pro At-FIS2, Pro At-ZHOUPI, and Pro Nt-CAT1 (Suzuki et al, 1995;Luo et al, 2000;Yang et al, 2008), the epidermal layer of the embryo-specific promoter Pro At-ML1 (Sessions et al, 1999), the meristem-specific promoters Pro At-STM and Pro At-CLV3 (Long et al, 1996), and the phloem-specific promoter Pro At-SUC2 (Juergensen et al, 2003). At-STM, At-ML1, and At-SUC2 promoter entry clones were a gift from George Coupland , and CAT1 promoter was a gift from Gerhard Leubner (Leubner-Metzger, 2005). The At-FIS2, At-ZHOUPI, and At-CLV3 promoters were amplified from Col genomic DNA using specific primers with Gateway tails.…”

“…Nonenzymatic processes have been proposed to alleviate dormancy and experimental evidence for a role of reactive oxygen species in dormancy release by after-ripening in sunflower (Helianthus annuus) has been presented (Oracz et al, 2007;Bazin et al, 2011). An alternative, but not mutually exclusive, theory for the after-ripening mechanism is provided by indirect evidence for the occurrence of humid pockets within dry seeds that would enable transcription and translation of germination factors (Leubner-Metzger, 2005).…”

A Review: Biological and Technological Functions of Barley Seed Pathogenesis-Related Proteins (PRs)

“…Expression of (1,3)-β-glucanases in healthy developing tissues suggests that, in addition to a possible role in defense, they may have a complex association with normal developmental processes in barley 365 . Multiple isoforms of seed (1,3)-β-glucanases that differ in size, isoelectric point, primary structure, cellular localization and pattern of expression have been implicated in diverse physiological and developmental processes in the uninfected plant, including seed development 37 , seed germination and dormancy release 182,183 .…”