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 pump’s activation is essential for the maintenance of membrane potential and ion homeostasis in the cytoplasm of mesophyll under salt stress.

Item Type:	Refereed Article
Keywords:	salinity, broad bean, mesophyll, flux, membrane potential, potassium, photosynthesis, H+-ATPase
Research Division:	Biological Sciences
Research Group:	Plant Biology
Research Field:	Plant Physiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Biological Sciences
Author:	Percey, WJ (Mr William Percey)
Author:	Shabala, L (Dr Lana Shabala)
Author:	Breadmore, MC (Professor Michael Breadmore)
Author:	Guijt, RM (Dr Rosanne Guijt)
Author:	Bose, J (Dr Jayakumar Bose)
Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	93364
Year Published:	2014
Web of Science® Times Cited:	10
Deposited By:	Tasmanian Institute of Agriculture
Deposited On:	2014-07-29
Last Modified:	2017-11-02
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