Morphological and anatomical differences in Aleppo pine seeds from serotinous and non-serotinous cones

Mediterranean communities have been historically conditioned by fire and
have therefore developed adaptive traits. Serotiny is a strategy that increases fire resilience
by storing seeds in the canopy, protecting them from heat and delaying their dispersion.
Aleppo pine is an important serotinous tree species in the low altitude, near-coastal
Mediterranean Basin. Differences in serotinous and non-serotinous cones have been
detected previously but in order to resolve a gap in the knowledge on seed adaptation to
fire, we focused this study on two fire-prone habitats in southern Italy. Several cones were
sampled and opened in an oven at two different temperatures in order to group seeds
according to provenance and cone type (serotinous or non-serotinous). The sampled seeds
were weighed and their coats were removed. Seed size, embryo diameter and nutritive
tissue thickness were recorded. We found that seeds with greater weight and size came
from the more humid site and from non-serotinous cones. Also, we observed wax and
cutine cells formed a thicker seed coat in seeds from the more humid site using a scanning
electron microscope. The scanning electron microscopy/energy dispersive X-ray spectroscopy
showed higher Si and Ca concentrations in the covers of serotinous seeds. Seeds
from different provenance and cone types have anatomic and morphological differences
that confer different properties against heating. This knowledge can improve post-fire
management and promote restoration tools.