Pyramiding physiological traits in plant breeding for salinity tolerance using electrophysiological techniques

Pyramiding physiological traits in plant breeding for salinity tolerance using electrophysiological techniques Professor Sergey Shabala School of Agricultural Science, University of Tasmania, Australia Over the past decades, breeding for salinity tolerance both in Australia and worldwide was essentially empirically-driven and relied mainly on plant phenotyping under field or glasshouse conditions. However, given the complexity and plethora of physiological and genetics mechanisms conferring salinity tolerance in plants, the practical outcomes of such approaches are disappointingly low. It has become evident that there is an urgent need to quantify a specific contribution of each of these diverse (and often controversial) mechanisms towards salinity tolerance. In my talk I will show how application of the MIFE technique for non-invasive microelectrode ion flux measurement may assist in pyramiding physiological traits to create truly salt tolerant varieties. Using barley (Hordeum vulgare), wheat (Triticum aestivum) and quinoa (Chenopodium quinoa) species as examples I will show how the MIFE technique can be used to identify key cellular mechanisms conferring salinity tolerance in these species, as well as to screen existing germplasm to select potential “donors” of these genes. Among these traits, I will focus on (1) functional characterisation of SOS1 activity in plant roots; (2) essentiality and mechanisms beyond root’s ability to retain K+; (3) control of xylem Na+ and K+ loading; (4) vacuolar Na+ sequestration; and (5) oxidative stress tolerance. The major focus of my talk will be on cytosolic K+ homeostasis as a key determinant of plant salinity stress tolerance. I will reveal the molecular identity of key plasma membrane transporters involved in controlling this trait and show the evidence for the causal relationship between plant’s ability to retain K+ and programmed cell death in root tissues. The prospects of plant breeding for salinity tolerance by targeting specific genes underlying the above cellular mechanisms will be discussed.