Scientists have sequenced the avocado genome in a major breakthrough for research into the fruit. The new study sheds light on the fruit's origins and lays the groundwork for future improvements to farming.
A study has revealed that Hass inherited 61% of its DNA from Mexican varieties and 39% from Guatemalan ones.
The research also provides vital reference material for learning about the function of individual avocado genes. This could lead to genetic engineering to boost productivity, improve disease resistance and create new characteristics.
Additionally, scientists sequenced other varieties from Mexico, Guatemala and the West Indies.
The National Laboratory of Genomics for Biodiversity (LANGEBIO) in Mexico, Texas Tech University, and the University at Buffalo led the project. The research was published on August 6 in the Proceedings of the National Academy of Sciences.
Study sheds light on disease resistance
Luis Herrera-Estrella, PhD, a plant genomics professor at Texas Tech, said avocados have an "enormous importance globally".
"Although most people will have only tasted Hass or a couple of other types, there are a huge number of great avocado varieties in the species' Mexican center of diversity, but few people will have tried them unless they travel South of the U.S. border," he said.
"These varieties are genetic resources for the avocado's future. We needed to sequence the avocado genome to make the species accessible to modern genomic-assisted breeding efforts."
Victor Albert, PhD, another study leader, said: "Our study sets the stage for understanding disease resistance for all avocados".
“If you have an interesting tree that looks like it’s good at resisting fungus, you can go in and look for genes that are particularly active in this avocado," he said.
"If you can identify the genes that control resistance, and if you know where they are in the genome, you can try to change their regulation. There’s major interest in developing disease-resistant rootstock on which elite cultivars are grafted."
Avocado genome to aid breeding programs
The new study uses genomics to investigate the family history of the avocado, known to scientists as Persea americana. The discoveries could lead to "faster and more effective breeding programs", according to Herrera-Estrella.
“We study the genomic past of avocado to design the future of this strategic crop for Mexico,” he said.
“The long life cycle of avocado makes breeding programs difficult, so genomic tools will make it possible to create faster and more effective breeding programs for the improvement of this increasingly popular fruit.”
The avocado belongs to a relatively small group of plants called magnoliids. These diverged from other flowering plant species about 150 million years ago.
The research supports the hypothesis that magnoliids predate the two dominant living lineages of flowering plants - eudicots and monocots.
“One of the things that we did in the paper was try to solve the issue of what is the relationship of avocados to other major flowering plants? And this turned out to be a tough question,” Albert says.
“Because magnoliids diverged from other major flowering plant groups so rapidly and so early on, at a time when other major groups were also diverging, the whole thing is totally damn mysterious."
While the research made contributions toward finding an answer, it didn't arrive at a "firm conclusion".
Magnoliids were estimated by a 2016 research paper to encompass about 11,000 known living species on Earth, including avocados, magnolias and cinnamon. In comparison, there are 285,000 species of eudicots and monocots