Structure of the Chemical and Genetic Diversity of the True Lavender over Its Natural Range.

Yolande Despinasse,Sylvie Baudino,Sandrine Moja,Frédéric Jullien,Jean-Marie Bessière,Bernard Pasquier,Catherine Soler,Florence Nicolè

doi:10.3390/plants9121640

Abstract

The true lavender Lavandula angustifolia Miller is a Mediterranean aromatic shrub widely cultivated for its high quality essential oil used in perfumery and phytotherapy. Despite its economic importance, the intra-specific diversity among wild, non-cultivated plants remains poorly understood. We analyzed the structure of the chemical and genetic diversity of plants from 14 sites sampled over the entire native range of the true lavender. Volatile organic compounds of inflorescences were analyzed using gas chromatography coupled to mass spectrometry. Genotyping was performed with fingerprinting genetic markers. To limit the influence of environmental variability on chemical composition, plants were grown in the same conditions in a common garden. Without prior knowledge, discriminant analysis of principal component identified unambiguously four distinct chemotypes among three genetic populations. Co-inertia analysis and supervised analysis which integrated multiple datasets indicated a strong congruency between chemical and genetic patterns. Two distinct genetic units were located at the edge of the distribution area in the south of Italy and in the northeast of Spain, and were associated with two distinct chemotypes. Our results confirmed the existence of three genetically distinct entities, suggesting speciation. All French populations and the Italian Piedmontese population were genetically homogeneous but separated in two distinct chemotypes. The dominant chemotype was present in the center of the native range in southeastern France and was at the origin of the current most cultivated French varieties. Its main compounds were linalyl acetate, linalool, and caryophyllene oxide. The second French chemotype was found in south of Massif Central and presented high abundance of valuable linalyl and lavandulyl acetates. Linalool, eucalyptol, β-caryophyllene, borneol, camphor, and cis-sabinene-hydrate were significantly associated with southern latitudes and their role would be worth exploring.

Highlights

The true lavender (Lavandula angustifolia Miller) is a medicinal and aromatic plant of the Lamiaceae family
We identified a total of 63 repeatable volatile organic compounds (VOCs) from our entire data set (14 sampled sites × 4.6 replicate plants per site + 25 plants from cultivated fields), which varied per site in the mean between
The discriminant analysis of principal components (DAPC, [22]) was successfully performed on both genetic and chemical data to infer the optimal number of clusters among the individuals without labeling the data

Summary

Introduction

The true lavender (Lavandula angustifolia Miller) is a medicinal and aromatic plant of the Lamiaceae family. The plant grows in an open arid habitat and is endemic to the Mediterranean climate. The. Plants 2020, 9, 1640; doi:10.3390/plants9121640 www.mdpi.com/journal/plants. Plants 2020, 9, 1640 distribution of the species is determined by the occurrence of calcareous sedimentary rocks and schists. The natural range includes the south of France, the French and Spanish Pyrenees, and the Italian. Upson and Andrews [1] identified two subspecies: L. angustifolia sp. Angustifolia in southern France and northern Italy, and L. angustifolia sp.

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