Getting to the root of salt tolerance in the model cereal crop, barley

MC Shelden and SD Tyerman

ARC Centre of Excellence in Plant Energy Biology, School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA 5064, Australia

Abiotic stresses are major causes of crop yield losses in agriculture significantly impacting on sustainability. Barley (Hordeum vulgare L.) is the most salt-tolerant cereal crop with excellent genetic/genomic resources and therefore is a good model to study salt tolerance mechanisms in cereals. Salinity results in a reduction in root growth, however, some species are able to maintain root elongation at salt concentrations that inhibit root growth; an adaptive mechanism to ensure seedling establishment and allow water and nutrient uptake. Barley cv. Clipper (malting barley) and Sahara (North African landrace 3771), the parents of the genetic mapping population used in this study, have previously been shown to have both a contrasting root growth phenotype and metabolite profile in response to the early phase of salinity stress. Clipper maintains a significantly higher relative root elongation rate in response to short-term salt stress that was associated with the synthesis and accumulation of compatible solutes indicating a potential role for these metabolic pathways in salt tolerance and the maintenance of root elongation. We now aim to identify the key genes and pathways in the roots that are involved in both perceiving osmotic changes in the soil and influencing root elongation, ultimately to increase salinity tolerance in crops. To elucidate the genetic basis for these mechanisms we are currently screening a double haploid mapping population of 146 lines derived from a Clipper x Sahara cross for their root phenotype. Future work will involve detailed genetic analysis of the mapping population using RNAseq in order to elucidate the genes involved in the maintenance of root elongation in response to salt stress. This study highlights the importance of utilizing spatial profiling and will provide us with a better understanding of abiotic stress response in plants at the tissue and cellular level.