Demonstrating the power of historical biological analysis, researchers have traced the remains of some Caribbean breadfruit (Artocarpus altilis) to Captain Bligh’s 1791-93 journey. This is based on a combination of DNA analysis, historical reports, and morphological data. Each of these has combined to connect the breadfruit to its history.
In the eighteenth century, Bligh on the ship HMS Providence led a mission to introduce seedless breadfruit trees from Tahiti to the Caribbean islands as a cheap food to feed slaves on British plantations. There is no record of the expedition compiling an inventory what types of breadfruit they introduced.
Bligh was the sailor more commonly associated with the “Mutiny on the Bounty” (the breadfruit transits happened after the mutinous event).
In a new study, plant biologists from Northwestern University used a variety of tools to identify breadfruit lineages growing in the Caribbean today, and the analysis enabled the researchers to identify five lineages in the Caribbean and connected them to the original Tahitian lineages introduced in 1793.
The findings show that the original breadfruit tree cultivars (varieties produced by selective breeding) have survived for centuries and they are thriving.
Researcher Lauren Audi explains that it has always been puzzling why the Caribbean is one of the largest producers of breadfruit worldwide. She states: “We really don’t know much about the genetic diversity of the fruit in the Caribbean. Because this is an important crop for food security — especially for island nations that are highly susceptible to climate change — we wanted to characterize the genetic diversity of breadfruit crops in order to conserve them. The first step for that is to characterize the diversity of what we already have.”
It was puzzling to researchers that the seedless breadfruit trees are triploid (with three copies of chromosomes, instead of the typical two (diploid) chromosomal copies). Triploid breadfruit trees also are unable to reproduce sexually and can only survive if humans clonally propagate them.
Whatever mutation gave rise to the change can be extremely difficult to pinpoint genetically. To tackle the conundrum the researchers integrated local knowledge with historical documents and specimens, morphological data (observations about the fruits’ size, shape and texture) and targeted genome sequencing.
Here the researchers analysed more than 200 individual breadfruit specimens, focusing y on seedless breadfruit from St. Vincent and Tahiti. The process involved extracting and sequencing DNA from leaf samples. This enabled the researchers to identify eight major global breadfruit lineages and five of these represent the original 1793 introduction by the HMS Providence.
Historically, breadfruit has served as a major food source. Breadfruit is starchy and seedless, playing a culinary role like a potato. It is related to jackfruit, and it can be steamed, roasted, fried or fermented. Understanding more about food and its origins will play can increasingly important role in food security protocols.
The research appears in the journal Current Biology, titled “Linking breadfruit cultivar names across the globe connects histories after 230 years of separation.”
