Water relations and xylem structures of branches of Tokyo cherry (Prunus×yedoensis ‘Somei-yoshino’) were affected by the large gall disease

Abstract

I compared leaf water status, xylem structure, and xylem hydraulic conductivity between large gall diseased and healthy branches of Tokyo cherry (Prunus×yedoensis ‘Somei-yoshino’). In diseased branches, the midday leaf water potentials (Ψ_w^mid), leaf osmotic potentials at water saturation (Ψ_s^sat), leaf water potentials at the turgor loss point (Ψ_w^tlp), vessel diameters, and xylem specific hydraulic conductivities (K_S) were lower, while vessel densities were higher than those of healthy branches. However, the levels of K_S in the diseased area of large gall disease, where the gall had appeared, were observed to be significantly decreased compared to those of healthy branches. These results suggest that the large gall disease may have an impact on xylem structure, reducing xylem hydraulic conductance, leading to branch water deficit, and eventual death.