Data from: Salicaceae endophyte inoculation alters stomatal patterning and improves the intrinsic water-use efficiency of Populus trichocarpa after a water-deficit

Microorganisms may enhance plant resilience to water stress by influencing
their hosts’ physiology and anatomy at the leaf-level. Bacterial and yeast
endophytes, isolated from wild poplar and willow, can improve the
intrinsic water-use efficiency (iWUE) of cultivated poplar (Populus) under
water-deficits by lowering stomatal conductance (gsw). However, the
relevance of stomatal anatomy underlying this reduction remains unclear.
We hypothesized endophyte inoculation could change host stomatal anatomy,
and this would relate to decreases in gsw. We subjected Salicaceae
endophyte-inoculated and uninoculated Populus trichocarpa to well-watered
and water-deficit treatments in greenhouse studies. We examined the
changes of individual stomatal traits and related the composition of these
parameters, termed stomatal patterning, to leaf gas-exchange under light
saturation. After a water-deficit, inoculation improved iWUE at light
saturation from preserving carbon assimilation (Anet) and lowering gsw,
but these changes were independent of soil-moisture status. Drops in gsw
corresponded to underlying shifts in stomatal patterning. Inoculated
plants had smaller, more compact stomata and greater anatomical maximum
stomatal conductance (gsmax) relative to the control. Salicaceae
endophytes may alter stomatal density and size, lowering gsw and
increasing iWUE. Future efforts may quantify endophyte colonization of the
host to draw direct relationships between microbes and stomatal traits.