Pruning-induced tylose development in stems of current-year shoots of Vitis vinifera (Vitaceae)
Tyloses form in xylem vessels in response to various environmental stimuli, but little is known of the kinetics or regulation of their development. Preliminary investigations indicated that wounds seal quickly with tyloses after pruning of grapevine shoots. In this study, tylose development was analyzed qualitatively and quantitatively at different depths and times from pruning cuts along current-year shoots of grapevines at basal, middle, and apical stem regions. Tyloses developed simultaneously within a single vessel but much separated in time among vessels. Pruning caused prodigious tylosis in vessels of grape stems, extending to approximately 1 cm deep and to 7 d after wounding, but about half of the vessels did not become completely occluded. The fraction of vessels forming tyloses was greatest in basal (85%) and least in apical (50%) regions. The depth of maximum density of tyloses was 4 mm from the cut in the basal region and 2 min from the cut in the middle and apical regions. Tylose development was faster in the basal and middle than in the apical region. The pattern of tylose development is discussed in the context of wound repair and pathogen movement in grapevines.