Ann Bot. 2021 Aug 16:mcab106. doi: 10.1093/aob/mcab106. Online ahead of print.
ABSTRACT
BACKGROUND AND AIMS: In hierarchically reticulate venation patterns, smaller orders of veins form areoles in which stomata are located. This study aimed to quantify the spatial relationship among stomata at the areole level.
METHODS: For each of 12 leaves of Michelia cavaleriei var. platypetala, we assumed that stomatal characteristics were symmetric on either side of the midrib, and divided the leaf surface on one side of the midrib into 6 layers equidistantly spaced along the apical-basal axis. We then further divided each layer into three positions equidistantly spaced from midrib to leaf margin, resulting in a total of 18 sampling locations. In addition, for 60 leaves, we sampled three positions from midrib to margin within only the widest layer of the leaf. Stomatal density (SD) and mean nearest neighbour distance (MNND) were calculated for each section. A replicated spatial point pattern approach quantified stomatal spatial relationships at different distances (0-300 μm).
KEY RESULTS: A tendency towards regular arrangement (inhibition as opposed to attraction or clustering) was observed between stomatal centres at distances smaller than ca. 100 μm. Leaf layer (leaf length dimension) had no significant effect on local SD, MNND or the spatial distribution characteristics of stomatal centres. In addition, we did not find greater inhibition at the center of areoles, and in positions farther from the midrib.
CONCLUSIONS: Spatial inhibition might be caused by the one-cell-spacing rule, resulting in more regular arrangement of stomata, and it was found to exist at distances up to ca. 100 μm. This work implies that leaf hydraulic architecture, consisting of both vascular and mesophyll properties, is sufficient to prevent important spatial variability in water supply at the areole level.
PMID:34397092 | DOI:10.1093/aob/mcab106
