Welcome to brain Stuff from how stuff works. Hey, brain Stuff, I'm Lauren vocal Bomb, And if you wander the protocyle at your local grocery store, you'll find a dazzling variety of tomatoes, from cherry or grape shaped to massive beefsteaks and gnarly heirlooms. The same with squash, potatoes, cucumbers, and leafy greens. This bounty of diverse colors, shapes, and sizes isn't the result of natural selection, but rather human selection.
Over millennia, farmers and plant breeders have spotted useful mutations and fruits and vegetables. Taste your fruit better, yields novel shapes, and preserved those traits through conventional breeding techniques. The process is slow, but if you cross different strains enough times, eventually you may create something new enough and marketable enough to be called its own variety. That slow and steady conventional breeding process is about to get a big boost
from advances in genetic mapping. With a tomato or cucumber genome in hand, plant breeders don't have to wait months for a tomato plant to bear fruit to know whether the tomatoes will be pear shaped. Or round. Instead, they can look for tell tell markers and a seedling's DNA, the code for specific fruit shape, size, and color. This technique of marker assisted selection promises to cut years off
the traditional plant breeding process. One Esther vander Nap is at the forefront of genetic research into exactly how it plant's DNA instructs its fruit to grow long and lean like a hothouse cucumber, or round and squat like a beefsteak tomato. In her lab at the University of Georgia, post docs and undergraduates sliced tomatoes in half and place them on a flatbed scanner to measure the precise shapes
and sizes produced by different genetic combinations. In a paper published in November of twenty eighteen in the journal Nature Communications, vander Nap announced the discovery of two families of genes that appear to play key roles in making fruits and vegetables either round or long. Fruits and vegetables are technically a plant's edible organs, and those organs grow and develop
up through cell division. She explained, to make a certain shape, like a longer round shape, you need to have certain patterns of cell division, either the cells divide horizontally or they divide vertically, which makes sense. The more in organ cells divide horizontally by splitting down the middle, the more they're going to build up tissue horizontally, creating a fatter,
rounder fruit. What vander Nap and her colleagues discovered in the tomato genome is a specific gene called ovate that appears to be responsible for creating proteins that tell cells to divide in a vertical pattern. When more cells split side to side, the growth pattern produces an elongated fruit. Ovate is the difference between a perfectly round cherry tomato
and an oblong plum tomato. Wild tomatoes, like the native varieties found in Peru, Ecuador, and Mexico, are invariably small and round, says vander Nap, which means pear shaped and other elongated tomatoes are mutations that came along later as far back as the ninety Plant biologists called the elongation mutation ovate, but had no clue about the actual genetic
mechanism behind it. But vander Nap and her team identified the ovate protein as well as another family of proteins called trms that interact with ovate, and it provides another tool to plant breeders who are using marker assisted selection. If the ovate n tr M markers are present, you can be sure the fruit will be elongated. If one
or the other is missing, it's backed round. Vander Napp says this will speed up the breeding process and let growers focus on trickier traits like yield and pest resistance that aren't as easily linked back to one or two specific genes. So now the question is do these advances in plant genetics mean that your produce I will soon include square tomatoes or pyramid shaped pumpkins. Not likely, says vander Nap, but not because it's technically impossible. She says.
There are tons of bizarre mutations in the tomato genome that result in odd looking fruits, and since those mutations are naturally occurring, they could be isolated and replicated in the lab. But the problem with square tomatoes and other oddball shaped fruit is twofold, vander Nap says, First, there's
the GMO problem. If plant breeders use gene editing to directly tweak or replace genes in food plants, those trains are considered GMO, and some people get freaked out by the GMO label, even though genetically modified organisms as a category are no less or more safe than conventionally modified organisms. Second, exciting new fruit and vegetable shapes may not shape up in other ways. Vander Nap said, some mutations are so bizarre that no grower would grow them because they have
lots of other problems. They only have a few fruit per plant, or they taste terrible because when you grow a fruit in a really odd shape, you mess up the hormone balance. It may not be very juicy or tasty at all. If you really want to grow a square tomato, says vander Nap, just put a box around it, like you may have seen downe with other fruit like watermelons. Should those hit the scene at a premium price, you
can always try growing your own at home. There are plenty of instructions online for building your own square fruit boxes. Today's episode was written by Dave Ruse and produced by Tyler Clang for i Heeart Media and How Stuff Works. For more on this and lots of other well rounded topics, visit our home planet, how stuff Works dot com