Developmental and water deficit-induced changes in hydraulic properties and xylem anatomy of tomato fruit and pedicel

Xylem water transport from the parent plant into the fruit plays a crucial role in fruit growth, development, and quality formation. Current research on fruit hydraulics has attempted to partition the hydraulic resistance of the pathway over development. However, no consensus has been reached and this question has not been addressed in the context of changing plant and fruit water status under water deficit. We rigorously investigated the developmental changes of hydraulic property of the fruit and pedicel under well-irrigated condition and water deficit based on hydraulic measurements, fruit rehydration, dye tracing, light and electron microscopy, and flow modeling. A decline in water transport capacity did not occur in the pathway prior to the fruit, but within the fruit itself, which might lie in the xylem and/or outside-xylem pathway. The developmental pattern of pathway hydraulic resistance was not significantly influenced by water deficit. The changed xylemic water flow between the fruit and the parent plant due to a reduced driving force under water deficit could explain the reduced fruit water accumulation. This work provides new insights into the understanding of xylem water transport in fleshy fruits and its sensitivity to water deficit from a hydraulics perspective.