The history of the banana is more complicated than you could ever imagine (if you ever thought about it).
More than 7,000 years ago, the communities of Oceania began to develop selectively wild Musa acuminata plants for their selection characteristics. Over time the fruit of the plant gradually evolved into the famous sweet, seedless, conveniently packaged banana that we have all come to love.
Unfortunately today, most bananas we consume are clones of one variety. Without diverse genetic approaches to disease manipulation, it wouldn’t take much for a plague to decimate the global supply.
A close look at the genomes of various banana cultivars and their wild relatives has now revealed signs that other banana plant relatives contributed to its development, with evidence of three previously undescribed species or subspecies.
Learning more about them could give us new ways to protect existing varieties from pests and infectious diseases.
Different banana varieties can have two (referred to as diploid), three (triploid) or four (tetraploid) copies of each chromosome, making it more difficult to unravel the history of the delicious grass-like flowering plant.
In this latest study, scientists used genetic sequencing techniques to identify the genetic fingerprints of 226 different banana leaf extracts. By comparing wild and domesticated subspecies, the team was able to create a detailed “family tree” of the ancestors of the bananas we have today.
“Here we show that most of today’s diploid bananas derived from the wild banana M. acuminata they are hybrids between different subspecies,” says genetic resource scientist Julie Sardos from the Alliance of Bioversity International and CIAT in France.
“At least three additional wild, mysterious ancestors must have contributed to this mixed genome thousands of years ago, but have yet to be identified.”
The researchers believe that two of these three mystery ancestors are the same as those previously identified using a different genetic analysis approach, but now we have more information about these gaps in the banana tree’s family history and where the shared genomes lie. .
It means that there are species or subspecies of bananas out there that have never been recorded by scientists – although this does not necessarily mean that none of these banana species remain.
“Our personal belief is that they’re still living somewhere in the wild, either poorly described by science or not described at all, so they’re probably threatened,” says Sardos.
The team then went further to try to understand where these mysterious missing varieties might be growing by making comparisons with similar banana species we know about and their respective locations around the world.
One is likely to be from the area between the Gulf of Thailand and the western South China Sea, one is probably between northern Borneo and the Philippines, and the other looks like it is from the island of New Guinea.
The researchers say finding these missing ancestors is urgent – it will allow us to preserve the biodiversity they provide and ultimately allow better bananas to be grown in the future.
“Breeders need to understand the genetic makeup of today’s domesticated diploid bananas for their crosses between cultivars, and this study is an important first step towards the detailed characterization of many of these cultivars,” says bioinformatics scientist Mathieu Rouard, also from the Alliance of Bioversity International and CIAT.
The research has been published in Frontiers in Plant Science.