Plant-derived smoke induced activity of amylases, DNA replication and β-tubulin accumulation before radicle protrusion of dormant Avena fatua L. caryopses

Florets of Avena fatua (wild oat) did not germinate at temperatures from 5 to 35 °C, nor did caryopses at 5 and above 15 °C. Smoke–water (SW) was found to partly or substantially induce dormant florets and caryopses to germinate at temperatures from 10 to 25 °C, whereby almost all caryopses germinated at 15 and 20 °C. When florets were dry-stored at 25 °C for 4 months, their dormancy, and that of florets was markedly or completely, respectively, removed at 20 °C. Floret and caryopsis SW demand decreased with time of dry storage. Paclobutrazol, a gibberellin biosynthesis inhibitor, completely antagonized the stimulatory effect of SW on germination of caryopses. Gibberellic acid (GA₃) reversed inhibition caused by paclobutrazol applied alone or in combination with SW. SW enhanced α- and β-amylase activities in caryopses before radicle protrusion. SW increased α-amylase activity and reduced starch content more effectively in intact caryopses than in embryoless ones. SW enhanced β-tubulin accumulation and the transition from G₁ to S and also from S to G₂ phases before radicle protrusion. The results presented indicate that florets are more dormant than caryopses and less sensitive to SW at incubation temperatures from 20 °C. Germination induction of dormant Avena fatua caryopses by SW required gibberellin biosynthesis. SW induction of dormant caryopsis germination involves mobilization of starch and cell cycle activation.