Five Fatty Acyl-Coenzyme A Reductases Are Involved in the Biosynthesis of Primary Alcohols in Leaves.

The diploid is the D-genome donor to hexaploid wheat () and represents a potential source for genetic study in common wheat. The ubiquitous wax covering the aerial parts of plants plays an important role in protecting plants against non-stomatal water loss. Cuticular waxes are complex mixtures of very-long-chain fatty acids, alkanes, primary and/or secondary alcohols, aldehydes, ketones, esters, triterpenes, sterols, and flavonoids. In the present work, primary alcohols were identified as the major components of leaf cuticular wax in , with C26:0-OH being the dominant primary alcohol. Analysis by scanning electron microscope revealed that dense platelet-shaped wax crystals were deposited on leaf surfaces of . Ten putative wax biosynthetic genes encoding fatty acyl-coenzyme A reductase (FAR) were identified in the genome of . Five of these genes, , , , , and , were found expressed in the leaf blades. Heterologous expression of the five Ae.tFARs in yeast () showed that Ae.tFAR1, Ae.tFAR2, Ae.tFAR3, Ae.tFAR4, and Ae.tFAR6 were predominantly responsible for the accumulation of C16:0, C18:0, C26:0, C24:0, and C28:0 primary alcohols, respectively. In addition, nine paralogous genes were located on D chromosome of wheat and the wheat nullisomic-tetrasomic lines with the loss of and paralogous genes had significantly reduced levels of primary alcohols in the leaf blades. Collectively, these data suggest that , , , , and 6 encode alcohol-forming FARs involved in the biosynthesis of primary alcohols in the leaf blades of . The information obtained in enables us to better understand wax biosynthesis in common wheat.