Effects of foliar water uptake on embolism in excised Avicennia marina twigs

Full description

The presence and propagation of gas within the xylem conduits, embolism, is widely documented in plants. Embolism occurs in response to dehydration or freezing and thawing, yet the mechanisms that enable plants to recover from embolism remain unclear. Foliar water uptake (FWU) may provide plants with access to water that could enable embolism refilling. Building on previous research that showed that FWU could restore leaf hydraulic conductance in Avicennia marina, this study aimed to test if embolism refilling was involved in leaf hydraulic recovery. Four dehydrated twigs from Avicennia marina (with water potential c. -4 MPa) were imaged using lab-based microCT at the dehydrated state, revealing the presence of stem and leaf emboli which were attributed to dehydration and cutting. Following tap water provision to the twig surface, twigs were imaged in periods of c. 4 h to track the rehydration and refilling process. MicroCT imaging revealed a c. 80% decrease in the leaf embolised area within 29 ± 10 h of wetting. Results revealed no change in embolism diameter following FWU, indicating that capillarity was not the main mechanism for refilling. This research suggests that Avicennia marina may be able to recover from embolism by absorption of foliar water. Full details are available at Fuenzalida, T.I., Blacker, M.J., Turner, M., Sheppard, A. and Ball, M.C. (2023), Foliar water uptake enables embolism removal in excised twigs of Avicennia marina. New Phytol, 237: 1136-1145. https://doi.org/10.1111/nph.18613. This research was funded by the Australian Research Council through grant DP180102969: Top-down rehydration: the role of multiple water sources in maintaining hydraulic function of mangroves along gradients in salinity and aridity.

Notes

1.
56.1 kB.

Significance statement

Direct observation of embolism refilling in response to foliar wetting.