Aerial parts of plants are separated from the environment by a cuticle which functions in protection against desiccation and pathogen attack. Recently, we reported on a barley mutant with defect in the 3-KETOACYL-CoA-SYNTHASE (HvKCS6) gene, resulting in reduced coverage of the cuticle with epicuticular waxes. Spores of adapted and non-adapted powdery mildew fungi germinated less frequently on mutant leaves possibly because plant derived signals are missing. We used a shoot and root phenotyping facility to test whether depletion in epicuticular waxes negatively impacts plant performance under water-limiting conditions. While shoots of mutant plants grew slower at well-watered conditions than wild-type plants, they showed an equal or slightly better growth rate at water limitation. Also for roots, differences between mutant and parental line were less prominent at water-limiting as compared to well-watered conditions. Our results challenge the intuitive belief that reduced epicuticular wax might become a drawback at water limitation.
Keywords: C, carbon chain length; CER, ECERIFERUM; CUT, REQUIRED FOR CUTICILAR WAX PRODUCTION; DAS, days after sowing; GC-MS, gas chromatography-mass spectrometry; Hv, Hordeum vulgare; IBG-2, Institute of Biosciences and Geosciences-2 (Forschungszentrum Jülich GmbH); KCS, KETOACYL-CoA SYNTHASE; KETOACYL-CoA SYNTHASE; VLCFA, very long-chain fatty acid.; drought stress; epicuticular wax, cuticle, Hordeum vulgare, phenotyping; germination; mlo, mildew resistance locus O; powdery mildew.