Physical rupture of the xylem in developing sweet cherry fruit causes progressive decline in xylem sap inflow rate

Abstract

Xylem flow is progressively shut down during maturation beginning with minor veins at the stylar end and progressing to major veins and finally to bundles at the stem end. This study investigates the functionality of the xylem vascular system in developing sweet cherry fruit (Prunus avium L.). The tracers acid fuchsin and gadoteric acid were fed to the pedicel of detached fruit. The tracer distribution was studied using light microscopy and magnetic resonance imaging. The vasculature of the sweet cherry comprises five major bundles. Three of these supply the flesh; two enter the pit to supply the ovules. All vascular bundles branch into major and minor veins that interconnect via numerous anastomoses. The flow in the xylem as indexed by the tracer distribution decreases continuously during development. The decrease is first evident at the stylar (distal) end of the fruit during pit hardening and progresses basipetally towards the pedicel (proximal) end of the fruit at maturity. That growth strains are the cause of the decreased conductance is indicated by: elastic strain relaxation after tissue excision, the presence of ruptured vessels in vivo, the presence of intrafascicular cavities, and the absence of tyloses.

Characterizing Neck Shrivel in European Plum

“…Empirical observations indicate that vascular transport also may be involved. For example, it has been reported for a number of fruit crops, [e.g., sweet cherry (Grimm et al, 2017;Winkler et al, 2016)] that a wave of increasing xylem dysfunctionality progresses basipetally from the stylar end of the fruit to the pedicel end. If this was also the case in european plum, a diurnal backflow of xylem water from fruit to tree, under daytime conditions of high foliar evaporative demand, may dehydrate the pedicel end of the fruit (via its still-functional xylem), but not the stylar end of the fruit (which is protected by its now-dysfunctional xylem) Volz, 1993, 1998).…”

Not all ‘pine cones’ flex: functional trade‐offs and the evolution of seed release mechanisms

“…This initial release often depends on specialized tissues that cause the direct abscission of propagules, typically associated with dehydration (Martone et al ., ; Dumais & Forterre, ), or that cause tissues enclosing the seeds to bend or break apart, most dramatically in plants whose fruit capsules explode to scatter seeds (Romanov et al ., ). Because vascular tissue may also play an important role in propagule abscission (Grimm et al ., ), specific adaptations for seed or fruit release in the xylem could also potentially influence the broader physiological function of reproductive structures.…”

Sugar Metabolism in Stone Fruit: Source-Sink Relationships and Environmental and Agronomical Effects

“…In the flesh, various branches diverge off the main bundles and ramify and anastomose throughout the flesh (Ragland, 1934;Tukey and Young, 1939;Sterling, 1953;Grimm et al, 2017). The relative contribution of xylem and phloem to fruit growth is dependent upon several factors that include the material that is being imported, the species of the stone fruit, the time of day, and both the tissue and the stage of fruit development (Matthews and Shackel, 2005;Morandi et al, 2007;Brüggenwirth and Knoche, 2016).…”