Germination of 10 midland plant species from the eastern Mediterranean Basin: effects of smoke, syringaldehyde, karrikinolide and cyanohydrin

Abstract

The beneficial effects of smoke and its constituents, karrikinolide (KAR1) and cyanohydrin glyceronitrile, on the germination of Mediterranean lowland species are well‐documented. However, very little is known about the role of these signals on the germination of plants at higher altitudes. In addition, lignin‐derived chemicals, such as syringaldehyde (SAL), have recently been proposed as overlooked cues for smoke‐induced germination. To address these gaps in the literature, we investigated the effects of smoke‐water and SAL on the germination of 10 midland species growing on serpentine soils. We also sought to determine whether SAL interacts with KAR1 and/or mandelonitrile (MAN, a cyanohydrin) to enhance seed germination. The results show that smoke‐water significantly improved the germination of three species (Barbarea duralii, Digitalis cariensis and Turritis laxa). SAL, on the other hand, had no positive effect on the germination of the 10 species tested. Furthermore, three smoke‐sensitive species and Verbascum cariense responded to KAR1 and/or MAN. Finally, SAL did not exert any synergistic effects on germination in interaction with KAR1 and MAN. In conclusion, we provide evidence that smoke is an important germination cue also for Mediterranean midland species. Moreover, SAL did not play a role in stimulating germination in smoke‐sensitive species, either independently or in combination with other smoke chemicals.