Ion transport in broad bean leaf mesophyll under saline conditions
Percey, WJ and Shabala, L and Breadmore, MC and Guijt, RM and Bose, J and Shabala, S, Ion transport in broad bean leaf mesophyll under saline conditions, Planta, 240, (4) pp. 729-743. ISSN 0032-0935 (2014) [Refereed Article]
Modulation in ion transport of broad bean (Vicia faba L.) mesophyll to light under increased apoplastic salinity stress was investigated using vibrating ion-selective microelectrodes (the MIFE technique). Increased apoplastic Na+ significantly affected mesophyll cells ability to respond to light by modulating ion transport across their membranes. Elevated apoplastic Na+ also induced a significant K+ efflux from mesophyll tissue. This efflux was mediated predominately by potassium outward rectifying channels (84 %) and the remainder of the efflux was through non-selective cation channels. NaCl treatment resulted in a reduction in photosystem II efficiency in a dose- and time-dependent manner. In particular, reductions in Fv′/Fm′ were linked to K+ homeostasis in the mesophyll tissue. Increased apoplastic Na+ concentrations induced vanadate-sensitive net H+ efflux, presumably mediated by the plasma membrane H+-ATPase. It is concluded that the observed pumpís activation is essential for the maintenance of membrane potential and ion homeostasis in the cytoplasm of mesophyll under salt stress.