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  • This episode is brought to you by Nature's Fynd,

  • a fungi-based food company for optimists.

  • Click the link in the description to discover the science

  • behind Nature's Fynd fungi-based foods.

  • [♪ INTRO]

  • If you pick up some corn at the grocery store,

  • odds are the kernels are yellow or white.

  • So you might just think that's the color corn

  • or maize, as it's more commonly known around the world.

  • But check this out.

  • It's called Glass Gem corn, and that rainbow is

  • a breathtaking display of the natural genetic variation that exists for maize.

  • This extra-colorful corn exists thanks to one man's journey to connect with

  • his Cherokee heritageas well as some neat aspects of maize genetics.

  • The varieties of maize grown on a large scale are carefully bred to have cobs

  • that are all the same size and shape and ready to harvest at the same time.

  • And while that helps ensure high yields and efficient processing,

  • it also means less diversity at the genetic level.

  • And slight variations in genes can make all the difference

  • when it comes to resisting a pest or tolerating drought conditions.

  • So these homogeneous crop varieties are more vulnerable to all sorts of threats.

  • But, lucky for maize, not everyone prizes such a shallow gene pool.

  • Even though you don't run into them every day, there are dozens of distinct kinds

  • of maize and countless sub-varieties grown around the world, mostly on a small scale.

  • In fact, people have been growing maize for thousands of years.

  • And in many cultures, including Native American ones,

  • maize is more than a cropit's an important part of their culture and heritage.

  • That's where the story of Glass Gem begins.

  • Several decades ago, a man named Carl Barnes started growing corn varieties

  • in a more traditional way, as a way of connecting with his Cherokee heritage.

  • Because of that, he focused on growing older varieties, including some

  • that he collected from friends who belonged to different Native tribes.

  • Many of these varieties were bred to do better in diverse environments

  • and for different uses.

  • Like different corns for popping, eating fresh, or grinding for flour.

  • And Barnes grew lots of these different corns together and let them cross-pollinate

  • like his ancestors did.

  • This let their genes mingle and expanded the gene pool.

  • He also took a special interest in saving seeds

  • that showed unusual and interesting colors.

  • He passed some of these to a friend, who then passed them along

  • to another friend, who mixed them with a couple more varieties for good measure

  • and grew them on a larger scale.

  • And all of this reclaiming, interbreeding, and seed exchange

  • was the key to making the beautiful rainbow of Glass Gems!

  • Now, no one has specifically looked into the genetics of Carl's corn.

  • But scientists have mapped the maize genome.

  • And we know that kernel color comes from colorful molecules called pigments.

  • These pigments are produced by enzymes that work together

  • sort of like a chemical assembly line.

  • And those enzymes are coded for in the plant's DNA.

  • There are also other genes whose products

  • switch parts of the assembly line on or off.

  • So differences in any of these genes can affect kernel color!

  • And not only can variously colored pigments be present, absent,

  • or present in different amounts, they can form in different tissue layers of the kernel,

  • which adds interesting visual effects and more variation.

  • For instance, the starchy interior of the kernel ranges from white to deep yellow,

  • depending on the amount of yellow carotenoids in it.

  • Other colors come from anthocyanins in one or both

  • of the kernel's thin outer layers.

  • These pigments come in reds, purples, and blues, and the intensity

  • can range from nearly black to the pale pastels you see in Glass Gems.

  • And you get even more variation by laying them over each other.

  • Like, a pale blue outer layer over a yellow interior could make a kernel look green.

  • As for each kernel being different

  • well, that's because they're all separate individuals... like, siblings.

  • You see, each ear is actually a whole bunch of

  • female reproductive tracts stuck together.

  • Those hairy parts, called silks, are like direct pipelines, each to a separate womb

  • of sorts containing an egg with a unique combination of half the plant's genes.

  • That's the future kernel.

  • Meanwhile, the tassel at the top of the plant contains the male reproductive bits.

  • That's where all the pollen is made.

  • And each pollen grain also has a unique combination of half the plant's genes.

  • Now, pollen travels on the wind.

  • It scatters across a field.

  • And if a pollen grain manages to land on a silk,

  • it travels down and its genes unite with the egg's.

  • So one plant's pollen can land on a bunch of different ears.

  • And each silk could, theoretically, receive pollen from a different plant.

  • Which means each kernel not only has a unique mix of genes from its parents,

  • each one can have a different father!

  • This is also true on big farms.

  • But, because all the plants are so genetically similar,

  • you don't end up with much kernel variety in each cob.

  • Barnes was growing multiple kinds of maize.

  • So there was a ton of genetic variation within his fields.

  • And the mixing and matching of these

  • brought all sorts of different gene combinations together!

  • That's ultimately how his corn ended up so colorful.

  • Sadly, Carl Barnes passed away in 2016, but his amazing corn lives on.

  • You can even buy it and grow it yourself!

  • And all the heirloom varieties and cross-pollination he fostered

  • didn't just make for prettier fall decor

  • they also help give maize a better chance of surviving long term.

  • The varieties that are grown on a large scale aren't just uniformly colored.

  • They tend to be more genetically uniform in all ways,

  • so they're more uniformly vulnerable to threats like drought, pests, and disease.

  • But other varieties carry variations in thousands of genes

  • that underlie important crop traits.

  • Barnes was part of a renewed movement to preserve this genetic diversity.

  • Today, there are seed-saving programs in place to catalog

  • and store traditional and regional varieties.

  • And farmers in some places never stopped growing maize the old way!

  • Like Barnes with his open pollinated fields and seed sharing,

  • they recognize that maize benefits from spreading its genes.

  • And unlike seed banks, these farmers keep diverse varieties alive and evolving.

  • Chances are, we'll need some of that diversity someday, when a nasty pest

  • comes along or something else threatens to wipe out this staple crop.

  • So we should be grateful to Barnes and all the other farmers out there

  • who are keeping the world's corn delightfully colorful.

  • Now, maize isn't the only crop likely to face threats in the future.

  • Our changing climate threatens basically everything that we're growing.

  • But there are some yummy sources of protein that can take the heatlike fungi!

  • Thanks to a breakthrough in fermentation technology, the folks at Nature's Fynd

  • are turning a fungi with origins in Yellowstone National Park

  • into delicious, protein-packed foods that are both meat and dairy free.

  • I really enjoyed getting to try Nature's Fynd meatless breakfast patties.

  • I love a good breakfast patty

  • and these ones give you that salty, savory flavor that you're looking for.

  • You can click on the link in the description to check out the science

  • behind their fungi-based foods, or follow with their story over on Instagram!

  • [♪ OUTRO]

This episode is brought to you by Nature's Fynd,

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B2 中高級 美國腔

世界上色彩最丰富的玉米的科学(The Science of the World's Most Colorful Corn)

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    joey joey 發佈於 2021 年 06 月 04 日
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