Expression Analysis and Functional Characterization of CER1 Family Genes Involved in Very-Long-Chain Alkanes Biosynthesis in Brachypodium distachyon

Abstract

Cuticular wax accumulation and composition affects drought resistance in plants. <i>Brachypodium distachyon</i> plants subjected to water deficit and polyethylene glycol treatments resulted in a significant increase in total wax load, in which very-long-chain (VLC) alkanes were more sensitive to these treatments than other wax compounds, implying that VLC alkanes biosynthesis plays a more important role in drought resistance in <i>B. distachyon</i>. <i>ECERIFERUM1</i> (<i>CER1</i>) has been reported to encode a core enzyme involved in VLC alkanes biosynthesis in Arabidopsis (<i>Arabidopsis thaliana</i>), but few corresponding genes are investigated in <i>B. distachyon</i>. Here, we identified eight <i>CER1</i> homologous genes in <i>B. distachyon</i>, namely <i>BdCER1-1</i> to <i>BdCER1-8</i>, and then analyzed their sequences feature, expression patterns, stress induction, and biochemical activities. These genes had similar protein structure to other reported <i>CER1</i> and <i>CER1</i>-like genes, but displayed closer phylogenetic relationship to the rice <i>OsGL1</i> genes. They were further found to exhibit various tissue expression patterns after being induced by abiotic stresses. Among them, <i>BdCER1-8</i> gene showed extremely high expression in leaves. Heterologous introduction of <i>BdCER1-8</i> into the Arabidopsis <i>cer1</i> mutant rescued VLC alkanes biosynthesis. These results indicate that <i>BdCER1</i> genes are likely to be involved in VLC alkanes biosynthesis of <i>B. distachyon</i>. Taken together, <i>BdCER1-8</i> seems to play an explicit and predominant role in VLC alkanes biosynthesis in leaf. Our work provides important clues for further characterizing function of <i>CER1</i> homologous genes in <i>B. distachyon</i> and also an option to improve drought resistance of cereal crops.