Resin vesicles in conifer seeds: morphology and allelopathic effects

Abstract

The seed coat of fir (Abies), hemlock (Tsuga), and cedar (Thuja) species contain terpenoid resin vesicles. Although information is limited about the morphology and allelopathy of these vesicles, their damage during seed processing can negatively impact germination success. We examined resin vesicle morphology of western redcedar (Thuja plicata), eastern white-cedar (T. occidentalis), amabilis fir (Abies amabilis), balsam fir (A. balsamea), grand fir (A. grandis), and subalpine fir (A. lasiocarpa) seeds by 1 H magnetic resonance imaging to characterize resin vesicle volume, shape, and number. Western redcedar genotypes with known differences in the quantity of foliar monoterpenes also had parallel differences in the resin vesicle volume of corresponding seeds. Germination assays with the cedar and fir species, eastern hemlock (Tsuga canadensis), mountain hemlock (T. mertensiana), and western hemlock (T. heterophylla) confirmed that resin vesicle damage prior to stratification (moist chilling) significantly reduced germination success for most species. Extracts of these resin vesicles from the Abies and Thuja species strongly inhibited the germination of Arabidopsis Col-0 seeds but inhibited the germination of only a small percentage of Arabidopsis abscisic acidinsensitive mutant abi3-6 seeds. Resin extracts from Thuja species were 10 times more effective than those from Abies species in inhibiting Arabidopsis Col-0 germination.

Quantitative magnetic resonance imaging of Scots pine seeds and the assessment of germination potential

“…Previous studies related to MRI of conifer seeds utilizing SE pulse sequences provide similar signal intensities than the ones presented in this work, albeit obtained with a variety of magnetic field strengths between 7.1 and 9.4 T (Carrier et al 1999;Terskikh et al 2005b;Keeling et al 2018), compared to the 11.7 T in this work. For conifer seeds, use of GRE sequences has not been described previously and MRI studies on conifer seeds are in general quite limited.…”

“…Previously, MRI has been used to study imbibition of western white pine seeds (Pinus monticola Dougl. ex D. Don) (Terskikh et al 2005b), resin vesicles on seed coats of conifer seeds (Keeling et al 2018), and development of white spruce seeds (Picea glauca (Moench) Voss) (Carrier et al 1999). Beyond MRI, spectroscopic NMR methods and nuclei other than 1 H have also been occasionally utilized for the compositional assessment of conifer seeds (Terskikh et al 2005a(Terskikh et al , 2008.…”

…Fell Upas Sits, the Hydra-Tree of Death †, or the Phytotoxicity of Trees

“…Finally, allelopathic properties of terpenoid resin vesicles in the seed coat of fir ( Abies ), hemlock ( Tsuga ), and cedar ( Thuja ) species were demonstrated. Germination of Arabidopsis seeds was inhibited with resin vesicle extracts, and damage of resin vesicle prior to stratification had negative effects on their own germination for most species [159].…”

Evaluation of Different Geographic Provenances of Silver Fir (Abies alba) as Seed Sources, Based on Seed Traits and Germination

“…In the case of silver fir, the periodicity of seed production is abundant every 4-5 years in seed source trees, while it is reduced to 2-3 years on plantations [42]. The external integuments of silver fir seeds are rich in essential oils that have a germination-inhibiting effect; thus, silver fir is considered a species with a low germination capacity (25%-35%) [43,44]. Due to this fact, it is necessary to stimulate the germination capacity of the seeds through different techniques.…”