DORMANCY-ASSOCIATED EMBRYONIC MESSENGER-RNAS AND PROTEINS IN IMBIBINGAVENA-FATUA CARYOPSES

The mechanisms controlling seed dormancy maintenance and release are n ot understood. To characterize the molecular events accompanying dorma ncy release, two-dimensional gel electrophoresis was used to monitor c hanges in soluble proteins and in vitro translation products of embryo nic mRNA populations during imbibition of dormant and nondormant (afte r-ripened) Avena fatua L. caryopses. No differences were observed betw een in vitro translation products of mRNA extracted from dry dormant a nd nondormant embryos. However, the expression patterns of several imb ibition- and germination-associated mRNAs were temporally modulated du ring the first 24 h of imbibition. Two dormancy-associated mRNAs, repr esented by polypeptides D1 and D2, were differentially overexpressed i n dormant embryos after 3 h of imbibition. mRNA levels for D1 and D2 w ere about 8- and 3-fold higher, respectively, in dormant embryos than in nondormant embryos after 3 h of imbibition. Overexpression of D1 co ntinued through 12 h of imbibition, while expression of both mRNAs fel l to low and equivalent amounts in dormant and nondormant embryos afte r 24 h. Similar dormancy-associated changes in two soluble proteins we re observed during imbibition. The results demonstrate that steady-sta te levels of specific mRNAs and proteins change during early imbibitio n of dormant and nondormant A. fatua embryos and indicate that these c hanges may be associated with differential gene expression responsible for the maintenance of dormancy.