Publication details

Tree acclimation to limited water availability: Linking intervessel lateral contact and vulnerability to embolism



Year of publication 2019
Type Article in Periodical
Magazine / Source Bulletin of the Czech Society of Experimental Plant Biology and the Physiological Section of the Slovak Botanical Society
MU Faculty or unit

Faculty of Science

Description Tree resistance to drought is tightly coupled with sensitivity of xylem transport to failure due to extensive embolism spread. In response to drought, trees adjust structure of xylem conduits to minimize water losses and improve resistance to embolism. However, effect of drought on lateral contact between conduits is poorly described and its consequences for embolism spread remain elusive. Here, we analysed drought-induced modifications in xylem structure both in stems of cultivated seedlings and annual rings in branches collected from mature individuals of temperate, angiosperm tree species, and assessed relationships between intervessel lateral contact and xylem vulnerability to embolism. We observed decrease in vessel diameter (VD; up to -4 µm) and concomitant increase in vessel density (VDE; up to +100 n mm-2) both in seedlings and mature trees in response to limited water availability. In opposite, there was only a small drought-induced change in intervessel contact fraction (FVV; ±4%) and no obvious trend was observed in FVV across species, illustrating low phenotypic plasticity of this trait. However, interspecific differences in FVV were found to determine xylem vulnerability to embolism as there was a positive linear correlation between FVV and slope of the vulnerability curve. Therefore, species with more interconnected vessels reached critical hydraulic failure of xylem within smaller change in water potential. In addition, greater FVV was associated with higher ?50 (xylem water potential at 50% loss of hydraulic conductivity) and narrower hydraulic safety margins, (e.g., difference between midday leaf water potential and ?50). Results of this study demonstrate that species with densely interconnected xylem conduits are more vulnerable to embolism but, despite of greater risk of hydraulic failure during drought, they use less conservative hydraulic strategies.

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