Water transport in fleshy fruits: Research advances, methodologies, and future directions

Abstract

Fruits are reproductive organs in flowering plants and the harvested products of many agricultural crops. They play an increasingly important role in the human diet due to their nutritional values. Water is the most abundant component of most fleshy fruits, and it is essential for fruit growth and quality formation. Water is transported to the fruit via the vascular system (xylem and phloem) and lost to the air through the fruit surface due to transpiration. This minireview presents a framework for understanding water transport in fleshy fruits along with brief introductions of key methodologies used in this research field. We summarize the advances in the research on the patterns of water flow into and out of the fruit over development and under different environmental conditions and cultural practices. We review the key findings on fruit transpiration, xylem transport, phloem transport, and the coordination of water flows in maintaining fruit water balance. We also summarize research on postvascular water transport mediated by aquaporins in fruits. More efforts are needed to elucidate the mechanisms by which different environmental conditions impact fruit water transport at the micro-level and to better understand the physiological implications of the coordination of water flows. Incorporating fruit water transport into the research area of plant hydraulics will provide new insights into water transport in the soil-plant-atmosphere continuum.

Canopy Architecture and Sun Exposure Influence Berry Cluster–Water Relations in the Grapevine Variety Muscat of Alexandria

“…Fruit hydraulics are receiving increasing attention because of the importance of water transport for fruit growth and quality [ 29 ]. Berry water transport depends on the pathway resistance between several structures to which the berry is connected (e.g., peduncle, rachis, and pedicel) and the parent plant, as well as on the driving force for water flow.…”

Genome-Wide Identification and Expression Analysis of the Aquaporin Gene Family in Lycium barbarum during Fruit Ripening and Seedling Response to Heat Stress

“…Developing fruits are strong sink organs, and the accumulation of sugars in them causes a negative water potential, which endows AQPs with pivotal roles at both the tissue and cellular levels [ 3 , 28 , 29 ]. An attention study was conducted in tomato fruits, in which regulation of AQP expression can clearly modify fruit quality (e.g., size, flavor, nutrition, and firmness) by the method of deficit irrigation-derived water scarcity [ 3 , 28 , 29 ]. It has been shown in grapes that the discharge of surplus phloem water may be required for normal grape ripening [ 25 ].…”

Water Content of Plant Tissues: So Simple That Almost Forgotten?

“…This directly results in the loss of water compartmentalization, which affects the mechanical properties of the fruit, basically changing the fruit from being crunchy to juicy. The functional aspects of water transport and accumulation during fruit development have been recently reviewed, and readers are encouraged to seek further details [ 47 , 51 ].…”