Dormancy‐associated embryonic mRNAs and proteins in imbibing Avena fatua caryopses

Abstract

The mechanisms controlling seed dormancy maintenance and release are not understood. To characterize the molecular events accompanying dormancy release, two‐dimensional gel electrophoresis was used to monitor changes in soluble proteins and in vitro translation products of embryonic mRNA populations during imbibition of dormant and nondormant (after‐ripened) Avena fatua L. caryopses. No differences were observed between in vitro translation products of mRNA extracted from dry dormant and nondormant embryos. However, the expression patterns of several imbibition‐ and germination‐associated mRNAs were temporally modulated during the first 24 h of imbibition. Two dormancy‐associated mRNAs, represented by polypeptides D1 and D2, were differentially overexpressed in dormant embryos after 3 h of imbibition. mRNA levels for D1 and D2 were about 8‐ and 3‐fold higher, respectively, in dormant embryos than in nondormant embryos after 3 h of imbibition. Overexpression of D1 continued through 12 h of imbibition, while expression of both mRNAs fell to low and equivalent amounts in dormant and nondormant embryos after 24 h. Similar dormancy‐associated changes in two soluble proteins were observed during imbibition. The results demonstrate that steady‐state levels of specific mRNAs and proteins change during early imbibition of dormant and nondormant A. fatua embryos and indicate that these changes may be associated with differential gene expression responsible for the maintenance of dormancy.

Characterization of cDNA clones for differentially expressed genes in embryos of dormant and nondormant Avena fatua L. caryopses

“…Plants were grown in the greenhouse and seed collected and stored as previously described [10]. Seed lots were divided into two portions to obtain dormant (stored at -20 °C) and nondormant (afterripened at 2 3 + 4 °C for 10 months) samples which were used for all comparisons.…”

“…Seed lots were divided into two portions to obtain dormant (stored at -20 °C) and nondormant (afterripened at 2 3 + 4 °C for 10 months) samples which were used for all comparisons. Germination tests and all other manipulations were conducted using seeds from which lemma and palea were removed by hand as previously described [10]. Embryos excised from dormant and nondormant caryopses as described [10] are hereafter referred to as dormant and nondormant embryos, respectively.…”

“…In A.fatua, two-dimensional gel patterns of soluble proteins and mRNA in vitro translation products from embryos excised from dormant and nondormant caryopses provided direct evidence for regulation of dormancy-and nondormancy-associated mRNAs during early imbibition [ 10]. Of about 200 mRNA in vitro translation products, no differences were observed between mRNA populations from dry dormant and nondormant embryos.…”

A peroxiredoxin antioxidant is encoded by a dormancy-related gene,Per1, expressed during late development in the aleurone and embryo of barley grains

“…One would thus expect germination ability or inability to be reflected through molecular differences between dormant and non-dormant seeds during imbibition [23,33,39]. While some studies have focused on these molecular differences [9,32,33], only a few transcripts have been cloned which show differential expression patterns during imbibition. Using differential display, Johnsen et aI.…”

A molecular study of dormancy breaking and germination in seeds of Trollius ledebouri

“…In embryos of A. saccharum and P. menziesii a number of proteins were induced during dormancy breaking brought about by seed stratification [14,34]. Schneider and Gifford [30] found that new proteins were synthesized de novo in the megagametophyte of Pinus taeda coinciding with that period of stratification which released dormancy in the majority of the seed population, Dyer [7] and Li and Foley [21 ] both found several mRNAs that were upregulated in non-dormant embryos of A. fatua before visible germination commenced but did not appear in imbibed dormant embryos. In addition, Johnston et al [19] were successful in pinpointing several mRNAs that were specific to non-dormant (and also dormant) embryos of A. fatua using the technique of differential display.…”