Photosynthesis, leaf hydraulic conductance and embolism dynamics in the resurrection plant Barbacenia purpurea

The main parameters determining photosynthesis are stomatal and mesophyll conductance and electron transport rate, and for hydraulic dynamics they are leaf hydraulic conductance and the spread of embolism. These parameters have scarcely been studied in desiccation-tolerant (resurrection) plants exposed to drought. Here, we characterized photosynthesis and hydraulics during desiccation and rehydration in a poikilochlorophyllous resurrection plant, Barbacenia purpurea (Velloziaceae). Gas exchange, chlorophyll fluorescence, and leaf water status were monitored along the whole dehydration-rehydration cycle. Simultaneously, embolism formation and hydraulic functioning recovery were measured at leaf level using micro-computed tomography imaging. Photosynthesis and leaf hydraulic conductance ceased at relatively high water potential (?1.28 and ?1.54?MPa, respectively), whereas the onset of leaf embolism occurred after stomatal closure and photosynthesis cessation (<?1.61?MPa). This sequence of physiological processes during water stress may be associated with the need to delay dehydration, to prepare the molecular changes required in the desiccated state. Complete rehydration occurred rapidly in the mesophyll, whereas partial xylem refilling, and subsequent recovery of photosynthesis, occurred at later stages after rewatering. These results highlight the importance of stomata as safety valves to protect the vascular system from embolism, even in a plant able to fully recover after complete embolism.

Este trabajo fue apoyado por el proyecto PGC2018-093824-B-C41 del Ministerio de Ciencia, Innovación y Universidades (España), el Fondo Europeo de Desarrollo Regional (FEDER), y La Région Auvergne-Rhône-Alpes "Pack Ambition International 2020" a través del proyecto "ThirsTree" 20-006175-01, 20-006175-02. MN recibió el apoyo de la beca predoctoral BES-2015-072578, financiada por el Ministerio de Economía y Competitividad (MINECO) y el Fondo Social Europeo; y las becas postdoctorales Juan de la Cierva-Formación (FJC2020-043902-I y FJC2020-042856-I), financiadas por MCIN/AEI/10.13039/501100011033 (España) y la Unión Europea ("NextGenerationEU/PRTR").

Barbacenia purpurea

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