Spatial variations in leaf trichomes and their coordination with stomata
in Quercus variabilis across Eastern Asia
Abstract
Understanding leaf trait variation is critical for the prediction of
plant responses to global climate changes. Leaf trichomes are derived
from stomatal epidermal cells, which play critical roles in biotic
defenses and against abiotic stress. Previous studies reported spatial
variations in stomatal traits and their driving factors at the same
sampling sites. However, it remains unclear how leaf trichome densities
vary along large geographic gradients and whether trichomes and stomata
co-vary under environmental changes. We measured the leaf trichome
densities of 44 Quercus variabilis populations in situ across Eastern
Asia (24 to 51.8 °N, 99 to 137 °E) and 15 populations grown in a common
garden, and used structural equation modelling to evaluate their
relationships with climatic factors and stomatal traits. Our results
revealed that climatic factors not only had a direct effect on trichome
density, but also had indirect effects on trichome density through
stomatal density and leaf mass per area. Trichome density was positively
correlated with stomatal density whether in situ or in the common
garden, and both increased with drought, which implied that trichomes
may impact stomatal behavior and both traits may co-vary under certain
environmental conditions. Our results suggested that leaf trichomes
possess highly adaptive variation and are in close coordination with
stomata in response to climate changes. Our findings provide new
insights toward elucidating the interactions between leaf traits and the
adaptive strategies of plants under climate change.