Spatio-temporal water distribution and migration of sweetpotato treated with high voltage alternating electric field

• High voltage alternating electric field (HVAEF) inhibited sweetpotato water loss. • Spatio-temporal water distribution and migration of sweetpotato were investigated. • HVAEF reduced the osmotic potential variation between different parts than control. • Water transported via xylem vessels, vascular rays and intercellular plasmodesmata. • HVAEF targeted PIP-pTOM75 and PIP2;7 expression to lower osmotic potential gradient. Water loss is one of the major reasons for quality deterioration of postharvest agricultural products. High voltage alternating electric field (HVAEF) is an effective technology on water retention and quality maintenance. To examine the impact of HVAEF on the spatio-temporal water distribution and migration, the sweetpotato root was divided into three vertical sections: top, middle, and bottom. Additionally, the root was segmented horizontally into phloem, outer xylem, and inner xylem regions. The water content determination results showed that the top, middle, and xylem parts of the sweetpotato were abundant in water, indicating that the direction of water migration was from inside to outside, and from top to bottom. HVAEF maintained a 2%-5% higher water content and reduced osmotic potential variation between different parts of sweetpotato than control, contributing to less water loss. Low-field nuclear magnetic resonance showed a higher proportion of bound water in HVAEF treated sweetpotato, resulting in the reduced mobility. Transmission electron microscopy and optical microscopy observed the vertical water migration routes via xylem vessels, and horizontal water migration routes through vascular rays and plasmodesma, which might be the targets of HVAEF. Particularly, the one quarter gene expression of aquaporin PIP2;7 and doubled expression of PIP-pTOM75 in HVAEF treated sweetpotato resulted in lower osmotic potential gradient, which attenuated the water loss. This study draws a temporal and spatial water distribution map of postharvest sweetpotato to reveal the mechanism of HVAEF on water maintenance and provides a promising technology for food preservation.