Phenotypic diversity of barley spike waxes resulting from mutations at locuscer-n

Complementation, test crosses and F2 analyses have revealed that of 53 mutations influencing the epicuticular waxes on barley spikes and stems, (the uppermost internodes and leaf sheaths), one is dominantly and the other 52 recessively inherited alterations of thecer-n gene. The extent of the apparent wax loss or reduction is organ specific with the precise levels being susceptible to environmental factors. The ten analyzed mutants were divided into five types on the basis of their spike wax composition. Lipid classes derived from the acyl elongase system (alkanes, primary alcohols and esterified alkan-1-ols) and/or those arising via the β-keto acyl elongase system (β-diketones, hydroxy-β-diketones and esterified alkan-2-ols) can be affected. Furthermore, which and how many of the lipid classes synthesized by either system as well as the type of changes resulting are a property of the individual mutations. Whethercer-n represents a structural or regulatory locus for epicuticular wax biosynthesis is not clear, although the product of this gene must have a minimum of two functional sites.