Since ancient times, this beautiful flower has been used to make perfumes and essential oils. The aesthetic value of lavender attracts people’s attention. So what makes this flower so special? What is the “magic” compound that gives it its unique aroma? What is the genetic basis of these compounds? These questions have long puzzled scientists.
To find out, scientists in China sequenced the genome of lavender, known in the scientific community as Lavandula Angustifolia. The team, led by Dr. Lei Shi, a professor at the Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences and Beijing Botanical Garden, was particularly interested in the genetics and diversity of a class of volatile terpenoids produced by lavender.
Terpenoids play an important role in the biology of aromatic flowers including lavender. In the environment, terpenes have been shown to attract potential insect pollinators. In real life, terpenes offer their potential benefits through products such as essential oils, including stress relief and skin care. With these in mind, it is necessary to understand the basic principles of terpenoid biosynthesis at the genetic level in order to manipulate lavender to produce better quality compounds.
The team first analyzed high-quality reference genomic data from the Chinese lavender variety “Jing Xun 2”. Through phylogenetic analysis, they identified genomic events in the evolutionary history of lavender that led to the expansion of terpenoid biosynthetic genes in the species. Their analysis also yielded important insights into how these genes changed in response to changes in the environment in which they were grown.
First, the scientists collected genetic sequences from Chinese lavender cultivars. Next, they identified and named, or “annotated,” genomic regions in the lavender sequences, and performed phylogenetic analysis of these sequences to better understand the evolutionary history of lavender. They then identified events that affect the entire lavender genome, specifically the genes that produce terpenoids. Finally, they linked genes on the lavender genome sequence with different terpenes found in the plant to construct the gene-terpene network.
The results of their study showed that they successfully assembled 894.5MB of lavender genome sequences distributed on 27 chromosomes, which is probably the best quality lavender sequence assembly to date. In addition, the scientists were able to show that the lavenders completely underwent major genetic events, including replication of two whole genomes that allowed them to better adapt and thrive in the colder Mediterranean climate.
Explaining their observations, Dr Shi Lei said: “Plants have the ability to copy their genomes, and when this happens, the duplicated genes have the freedom to evolve to do other things. This has allowed plants to develop new machines to produce a wide variety of chemicals to fend off harmful microbes and herbivores, and to attract beneficial species such as bees to assist in pollination. In fact, Dr Shi’s explanation is backed up by his team’s findings. His team identified gene duplication caused by the aforementioned genetic events, which in turn led to the diversification of terpenoids. Upon further analysis, they also observed clusters of genes specifically corresponding to attractive and defensive terpenes.”
Dr Shi is excited about the potential real-world applications of this work. “The introduction of lavender to China can be traced back to the 1950s by pioneers at the Institute of Botany, Chinese Academy of Sciences. The deterioration of cultivated varieties is worrying and there is an urgent need for improved varieties. With a better understanding of the lavender genome, it will be easier for scientists to develop new varieties that may produce high-quality essential oils that are highly ornamental and resistant to pathogens and climate fluctuations.”
