Suzanne's Mom's Blog

For something a little bit different, consider “the vegetable that took over the world.” It turns out that different cultures not only develop their own versions of music and art but their own versions of the same edible plant. It helps that the plant in question has triplicated genes.

Gemma Tarlach reports at Atlas Obscura about “the single species that gives us turnips, bok choy, broccoli rabe” …

“The plant known as Brassica rapa has quite the history, one that, after decades of debate, is finally emerging. The single species, which humans have turned into turnips, bok choy, broccoli rabe (also known as rapini), and other residents of the produce aisle, began up to 6,000 years ago in Central Asia.

“[In June] Molecular Biology and Evolution published findings from an unprecedented study of B. rapa that pulled together genetic sequencing, environmental modeling, and the largest number of wild, feral, and cultivated samples ever collected. … The paper is a significant step forward in understanding how one of the planet’s most important agricultural species might weather climate change.

“ ‘This study is really great. I like the approaches they took, and the framework they placed it in,’ says Nora Mitchell, a plant evolutionary biologist at the University of Wisconsin-Eau Claire. Mitchell, who was not involved in the research. … She says the new paper’s environmental modeling — reconstructing conditions under which B. rapa was adapted to different locations, as well as forecasting what changing conditions might mean for its future — makes the study particularly compelling. …

” ‘The work is a particular achievement when you consider both the diversity and global spread of B. rapa crops, wild relatives, and feral varieties that have escaped farmers’ fields’ … says Alex McAlvay, lead author of the study and a botanist at the New York Botanical Garden. Now, he says, B. rapa, in various forms, ‘grows from Alaska to Tierra del Fuego. They grow in Oceania, they grow from Spain to Japan.’ …

“B. rapa’s ability to survive as a feral plant worldwide had created a lot of uncertainty about its origins. Botanists often look to wild relatives of crops to help understand where the plants were first domesticated. But B. rapa is everywhere and, before the new research, distinguishing truly wild species from feral escapees was almost impossible. …

“While genetic detective work is always a complex undertaking, McAlvay says he and his colleagues were particularly challenged by a ‘crazy mess’ of genes that originated in the ancestor of both B. rapa and its close relative B. oleracea, another single species that provides multiple vegetables: broccoli, cauliflower, cabbage, kale, and more.

‘One reason we think these species have this incredible diversity is that their ancestor had not only a duplication of their genome, but a triplication,’ says botanist Makenzie Mabry, who coauthored the new paper. …

“While humans and many other organisms inherit a single set of chromosomes, one half from each parent, some plants inherit double sets. The Brassica ancestor had three sets that, says Mabry. …

“ ‘There’s an additional layer of weirdness,’ on the road to domestication and diversification, adds McAlvay: Different cultures selected for certain traits in different parts of the plant. For example, we’re familiar with tomatoes in all colors, sizes, and flavor profiles, but they’re all the fruit of the plant Solanum lycopersicum. For B. rapa, however, ‘with turnip, you’re looking at the root, the underground stem of the plant. Tatsoi is the leaves. Broccoli rabe is the flowers,’ says McAlvay.

“ ‘In China, people saw the same kind of raw material, the turnip, and they did something totally different than the Italians and Spanish did,’ he adds, running down a list of water-rich bok choy, chunky turnips, bitter greens, jagged-leaf mizuna, and other B. rapa permutations worldwide. …

“Digging up B. rapa’s roots is more than an exercise in botanical history. … ‘Food security is a big issue, especially global food security. And with Brassica having so many crops, not only vegetables but for oils as well, it’s really important to continue producing these crop species in the face of climate change, increased drought, and nutrient changes, as well as crop blights and crop diseases,’ Mitchell explains. ‘It’s important to understand not only what happened in the past but how these plants might respond in the future, and to know what kind of genetic resources could increase diversity.’

“McAlvay believes the paper’s findings on weedy, feral varieties may prove particularly significant for breeding better B. rapa crops in the future. ‘For most of recent history, people have dismissed the stray dogs of the plant world as not particularly useful,’ he says. ‘But because they’re already adapted to really rough, tough environments, there’s some push, with the advent of gene editing, to be inspired by those turnips gone wild.’ ”

What a miracle is Nature! More at Atlas Obscura, here.