Characterization of the Genes Involved in Malic Acid Metabolism from Pear Fruit and Their Expression Profile after Postharvest 1‑MCP/Ethrel Treatment WangLibin MaMin ZhangYanru WuZhangfei GuoLin LuoWeiqi WangLi ZhangZhen ZhangShaoling 2018 In this study, five genes involved in malic acid (MA) metabolism, including a cytosolic NAD-dependent malate dehydrogenase gene (<i>cyNAD-MDH</i>), a cytosolic NADP-dependent malic enzyme gene (<i>cyNADP-ME</i>), two vacuolar H<sup>+</sup>-ATPase genes (<i>vVAtp1</i> and <i>vVAtp2</i>), and one vacuolar inorganic pyrophosphatase gene (<i>vVPp</i>), were characterized from pear fruit based on bioinformatic and experimental analysis. Their expression profile in “Housui” pear was tissue-specific, and their expression patterns during fruit development were diverse. During “Housui” pear storage, MA content decreased, which was associated with the downregulated transcripts of MA metabolism-related genes and cyNAD-MDH activity and higher cyNADP-ME activity. The response of MA metabolism to postharvest 1.5 μL L<sup>–1</sup> 1-MCP fumigation and 0.5 mL L<sup>–1</sup> ethrel dipping was distinct: 1-MCP fumigation upregulated gene expression and cyNAD-MDH activity and suppressed cyNADP-ME activity, and thus maintained higher MA abundance when compared with those in the control; on the other hand, an opposite behavior was observed in ethrel-treated fruit.