Plant material
Fully developed, undamaged leaves of Prunus dulcis (Mill.) D.A.
Webb and Pyrus communis L. were used for this study. Leaves of
each species were selected from the central part of current-year
sun-exposed shoots, of southeast facing branches in five mature trees
growing at the University of California Davis campus (38.542154° N,
121.796485° W, Davis, USA). Branches were randomly collected in the
early morning, enclosed in dark plastic bags containing damp paper
towels and transferred to the laboratory. Homogeneous looking leaves
were chosen from branches for further experimental treatments and
analyses.