Reducing stomatal density in Hordeum vulgare improves drought tolerance and water use efficiency

Manipulation of the expression of the epidermal patterning factor (EPF) family of secreted signalling peptides in order to regulate stomatal density has previously been demonstrated to improve water use efficiency in Arabidopsis thaliana (Franks et al., 2015). Following the sequencing of the barley genome an ortholog of EPF2 was identified and overexpressed. HvEPFL1 overexpression limits both entry into, and progression through, the stomatal lineage. Lines overexpressing HvEPFL1 showed significant increases over controls in terms of both water use efficiency and drought tolerance, without a detrimental effect on grain yield. This suggests that the manipulation of stomatal density could be utilised in order to futureproof crops against future climate change.