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

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.