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Article|06 Nov 2023|OPEN
Diverse O-methyltransferases catalyze the biosynthesis of floral benzenoids that repel aphids from the flowers of waterlily Nymphaea prolifera
Guanhua Liu1,2 ,† , Jianyu Fu2 ,† , Lingyun Wang3 , Mingya Fang3 , Wanbo Zhang1 , Mei Yang1,2 , Xuemin Yang1 , Yingchun Xu1 , Lin Shi3 , Xiaoying Ma1 , Qian Wang2,4 , Hui Chen2,4 , Cuiwei Yu5 , Dongbei Yu5 , Feng Chen6 , Yifan Jiang,1 ,
1College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
2Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China
3Provincial Key Laboratory of Characteristic Aquatic Vegetable Breeding and Cultivation, Jinhua Academy of Agricultural Sciences (Zhejiang Institute of Agricultural Machinery), Zhejiang Province 321000, China
4Graduate School of Chinese Academy of Agricultural Sciences, Beijing, 100081, PR China
5Hangzhou Tianjing Aquatic Botanical Garden, Zhejiang Humanities Landscape Co., Ltd., Hangzhou 310000, China
6Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA
*Corresponding author. E-mail: jiangyifan@njau.edu.cn
Both authors contributed equally to the study.

Horticulture Research 11,
Article number: uhad237 (2024)
doi: https://doi.org/10.1093/hr/uhad237
Views: 41

Received: 08 Jun 2023
Revised: 14 Nov 2023
Published online: 06 Nov 2023

Abstract

Nymphaea is a key genus of the ANA grade (Amborellales, Nymphaeales, and Austrobaileyales) of basal flowering plants, which serve as a key model to study the early evolution of floral traits. In this study, we comprehensively investigated the emission, biosynthesis, and biological function of the floral scent in a night-blossoming waterlily Nymphaea prolifera. The headspace volatile collection combined with GC–MS analysis showed that the floral scent of N. prolifera is predominately comprised by methylated benzenoids including anisole, veratrole, guaiacol, and methoxyanisole. Moreover, the emission of these floral benzenoids in N. prolifera exhibited temporal and spatial pattern with circadian rhythm and tissue specificity. By creating and mining transcriptomes of N. prolifera flowers, 12 oxygen methyltransferases (NpOMTs) were functionally identified. By in vitro enzymatic assay, NpOMT3, 6, and 7 could produce anisole and NpOMT5, 7, 9, produce guaiacol, whereas NpOMT3, 6, 9, 11 catalyzed the formation of veratrole. Methoxyanisole was identified as the universal product of all NpOMTs. Expression patterns of NpOMTs provided implication for their roles in the production of the respective benzenoids. Phylogenetic analysis of OMTs suggested a Nymphaea-specific expansion of the OMT family, indicating the evolution of lineage-specific functions. In bioassays, anisole, veratrole, and guaiacol in the floral benzenoids were revealed to play the critical role in repelling waterlily aphids. Overall, this study indicates that the basal flowering plant N. prolifera has evolved a diversity and complexity of OMT genes for the biosynthesis of methylated benzenoids that can repel insects from feeding the flowers. These findings provide new insights into the evolutional mechanism and ecological significance of the floral scent from early-diverged flowering plants.