LcERF19, an AP2/ERF transcription factor from <i>Litsea cubeba</i>, positively regulates geranial and neral biosynthesis

Abstract

The APETALA2/ETHYLENE RESPONSE FACTOR (AP2/ERF) transcription factors (TFs) are involved in the regulation of specialized terpenoid biosynthesis. However, the AP2/ERF TFs in <i>Litsea cubeba</i> have not been characterized and their role in the biosynthesis of terpenoids is unknown. Here, 174 LcAP2/ERF TFs were identified in <i>L. cubeba</i> and categorized into four subfamilies: 27 AP2, 7 RAV, 1 Soloist, and 139 ERF. Transcriptomic and qRT-PCR assays both showed that the expression levels of <i>LcERF19</i> were similar to that of terpene synthase <i>LcTPS42</i> in the pericarp, which is related to the synthesis of geranial and neral in <i>L. cubeba</i>. <i>LcERF19</i> was further shown to encode a nuclear-localized protein and its expression was strongly induced by jasmonate. Yeast one-hybrid and dual-luciferase assays showed that LcERF19 associated with GCC box elements of the <i>LcTPS42</i> promoter and promoted its activity. Transient overexpression of <i>LcERF19</i> in <i>L. cubeba</i> and overexpression of <i>LcERF19</i> in tomato resulted in a significant increase in geranial and neral. Our findings show that LcERF19 enhances geranial and neral biosynthesis through activation of <i>LcTPS42</i> expression, which provides a strategy to improve the flavor of tomato and other fruits.