Plant-derived smoke induced activity of amylases, DNA replication and \u03b2-tubulin accumulation before radicle protrusion of dormant Avena fatua L. caryopses

Abstract

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.