A research team in China has produced the high-quality reference genome for ‘Jingxun 2,’ a cultivar of the lavender (Lavandula angustifolia) recently bred by Chinese scientists.
The ecological function of the main volatiles emitted by opening flowers, flower buds, leaves, and stems of the lavender (Lavandula angustifolia): a large proportion of linalool, linalyl acetate, and lavandulyl acetate in opening flowers function as attractants for pollinators; at the flower bud stage, α-pinene, β-pinene, and β-ocimene, etc. provide defense against herbivores and predators; borneol, camphor, 1,8-cineole, camphene, and bornyl acetate are the main compounds in leaves and stems, and are always repellents to pests. Image credit: Li et al., doi: 10.1038/s41438-021-00490-6.
Lavandula is a distinctive genus that belongs to the species-rich and chemically diverse subclade Nepetoideae (3,600 species) within the family Lamiaceae.
The genus includes over 30 species and has over 2,500 years of recorded use by humans as flavor additives, fragrances, alternative medicine, and anti-herbivore agents.
Lavandula species produce various volatile terpenoids that serve as resources for essential oils and function in plant-insect communication.
To better understand the genetic basis of the terpenoid diversity in lavender, Professor Lei Shi from the Beijing Botanical Garden and Chinese Academy of Sciences’ Institute of Botany and colleagues sequenced the genome of the Chinese lavender cultivar Jingxun 2.
“Jingxun 2 is characterized by high levels of linalyl acetate and linalool and low amounts of camphor in its essential oil, making it the most valued lavender oil additive to many over-the-counter complementary medicines and cosmetic products in China,” the researchers said.
They identified the events that affected the entire lavender genome and specifically the terpenoid producing genes.
They then associated genes on the lavender genome sequences with different terpenoids found in the plant to construct gene-terpenoid networks.
They also found that the lavender underwent two rounds of whole-genome duplication 29.6 million and 6.9 million years ago, during the Eocene-Oligocene and Miocene-Pliocene transitions, respectively.
As a result of tandem duplications and lineage-specific whole-genome duplications, gene families related to terpenoid biosynthesis in lavender are substantially expanded compared to those of five other species in the Lamiaceae family.
“Plants have the capacity to duplicate their genomes and when this happens there is freedom for the duplicated genes to evolve to do other things,” Dr. Shi said.
“This has allowed plants to develop new machinery to make a diverse array of chemical compounds that are used to defend against attack from harmful microbes and herbivores, and to attract beneficial species such as bees to assist in pollination.”
The team’s results were published in the journal Horticulture Research.
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J. Li et al. 2021. The chromosome-based lavender genome provides new insights into Lamiaceae evolution and terpenoid biosynthesis. Hortic Res 8, 53; doi: 10.1038/s41438-021-00490-6
