Biochemistry

Potassium is known as a rate-limiting factor for crop yield and plays an important role in plants response under abiotic stresses. Recently, cytosolic K⁺ retention ability in leaf mesophyll has emerged as an important component of plant salt tolerance mechanism (Wu et al., 2013; Wu et al., 2014; Wu et al., 2015). In this protocol, the procedure for screening leaf mesophyll for K⁺ retention by the MIFE (microelectrode ion flux estimation) technique is described in detail using wheat as an example. By measuring NaCl-induced K⁺ efflux in leaf mesophyll, a large number of plant accessions can be screened and categorised according to their salinity stress tolerance. The method provides a rapid and reliable tool that targets the activity of specific membrane transporters directly contributing to salinity tolerance trait and, because of this, has a competitive advantage over traditional whole-plant phenotyping. While the focus of this protocol is on wheat, the suggested method may be adopted for screening K⁺ retention in leaf mesophyll in any other crop species.

Potassium is an essential element in plant growth and has an important role in regulating cell water potential and turgor in osmotic regulation. Potassium content in plants is high compared to trace elements, however, it is difficult to measure a relatively small change of potassium content in the large total. Here, we describe a procedure for measuring potassium in Arabidopsis that is easy to handle in preparative scale and avoids contamination.