A BAHD acyltransferase contributes to the biosynthesis of both ethyl benzoate and methyl benzoate in the flowers of Lilium oriental hybrid 'Siberia'

Yuechong Yue; Lan Wang; Manyi Li; Fang Liu; Junle Yin; Lijun Huang; Bin Zhou; Xinyue Li; Yunyi Yu; Feng Chen; Rangcai Yu; Yanping Fan

doi:10.3389/fpls.2023.1275960

A BAHD acyltransferase contributes to the biosynthesis of both ethyl benzoate and methyl benzoate in the flowers of Lilium oriental hybrid 'Siberia'

Front Plant Sci. 2023 Sep 29:14:1275960. doi: 10.3389/fpls.2023.1275960. eCollection 2023.

Authors

Yuechong Yue^{1

2}, Lan Wang¹, Manyi Li³, Fang Liu¹, Junle Yin¹, Lijun Huang³, Bin Zhou¹, Xinyue Li^{1

2}, Yunyi Yu^{1

2}, Feng Chen⁴, Rangcai Yu³, Yanping Fan^{1

2}

Affiliations

¹ The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China.
² Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, China.
³ College of Life Sciences, South China Agricultural University, Guangzhou, China.
⁴ Department of Plant Sciences, University of Tennessee, Knoxville, TN, United States.

Abstract

Lily is a popular flower worldwide due to its elegant appearance and pleasant fragrance. Floral volatiles of lily are predominated by monoterpenes and benzenoids. While a number of genes for monoterpene biosynthesis have been characterized, the molecular mechanism underlying floral benzenoid formation in lily remains unclear. Here, we report on the identification and characterization of a novel BAHD acyltransferase gene that contributes to the biosynthesis of two related floral scent benzoate esters, ethyl benzoate and methyl benzoate, in the scented Lilium oriental hybrid 'Siberia'. The emission of both methyl benzoate and ethyl benzoate in L. 'Siberia' was found to be tepal-specific, floral development-regulated and rhythmic. Through transcriptome profiling and bioinformatic analysis, a BAHD acyltransferase gene designated LoAAT1 was identified as the top candidate gene for the production of ethyl benzoate. In vitro enzyme assays and substrate feeding assays provide substantial evidence that LoAAT1 is responsible for the biosynthesis of ethyl benzoate. It was interesting to note that in in vitro enzyme assay, LoAAT1 can also catalyze the formation of methyl benzoate, which is typically formed by the action of benzoic acid methyltransferase (BAMT). The lack of an expressed putative BAMT gene in the flower transcriptome of L. 'Siberia', together with biochemical and expression evidence, led us to conclude that LoAAT1 is also responsible for, or at least contributes to, the biosynthesis of the floral scent compound methyl benzoate. This is the first report that a member of the plant BAHD acyltransferase family contributes to the production of both ethyl benzoate and methyl benzoate, presenting a new mechanism for the biosynthesis of benzoate esters.

Keywords: BAHD acyltransferase; biosynthesis; ethyl benzoate; floral scent; lily; methyl benzoate.

Grants and funding

The authors declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the National Natural Science Foundation of China (Grant no. 31870690), the Basic and Applied Basic Research Projects of Guangzhou (Grant no. 202201010372), and the Key-Areas Research and Development Program of Guangdong Province (Grant no. 2020B020220007 and 2020B020220009).