Climate change threatens to disrupt  basically every aspect of our lives, including what’s on our dinner tables.

Droughts in particular are looking like  they’ll be a major threat to our food supply, especially since crops like maize, wheat and rice are particularly vulnerable to dry weather. Which is why researchers have been trying  to make plants more drought resistant for decades, using high-tech  approaches like genetic modification.

And while they have been somewhat successful, genetically modified plants are not  the only way to tackle this problem. It turns out, a simple solution might  have been right under our fingernails this whole time–the soil-dwelling microbes  that make up a plant’s microbiome. [♪ INTRO] Anyone with the tendency to  forget to water their plants already knows about the  damage that drought can do. And that damage doesn't go  away when water the comes back.

While some of the molecular,  structural, and physiological changes caused by drought go back to  normal once the rain comes, in many cases those changes cause  physical damage that can’t be repaired. So even a short-term drought  can have long-term consequences. During drought conditions, plants are not able to get the nutrients they need from the soil.

Their leaves shrivel up and have  less surface area for photosynthesis, and their cells aren’t able  to elongate like usual. All of that combined means  that you get smaller plants with less edible mass that  just don’t taste as good. So a drought lasting one growing season can end up impacting the food supply for years.

Population growth is already  pushing agriculture to its limits, and with the frequency and severity  of droughts increasing thanks to climate change, we’re going  to find ourselves trying to feed more people with less food. And we’re actually already  starting to see this play out. In Europe, heatwaves and droughts have  roughly tripled the amount of grain that isn’t harvestable over the last 60 years, from 2.2% between 1964 and 1990 to  more than 7% between 1991 and 2015.

And the situation is even more dire in  developing nations in tropical regions, with wheat yields predicted to decline by roughly 15% in African and  Southern Asian countries by 2050. Which is why finding ways to  protect plants from droughts has been on scientists’ radars for decades. A lot of plants have coping strategies  to help them survive droughts, and there’s been lots of research  into genetic modifications to enhance drought resistance.

But it’s not just their genes that  can help plants survive dry times. It’s also their neighbors. Microbiomes are the communities  of tiny little organisms that live in an ecosystem, so the  bacteria, fungi, algae, all that jazz.

You may have heard about the human microbiome, but plants have microbiomes, too. Theirs include microbes that live both on  the inside and outside of the plant itself, and all of the little guys that  live in the soil around the roots. They help promote plant growth,  turn nitrogen into forms that plants can use, and slurp up  nutrients to pass along to their host.

And it turns out that some microbes also release molecules that play  a role in drought resistance. Some of these bacteria release  plant growth regulators, which alter growth by doing things  like impacting energy metabolism, increasing photosynthesis, and  boosting the antioxidant system. Other bacteria produce  enzymes that promote growth by lowering levels of ethylene, a hormone  that’s released when plants are stressed.

And some work by secreting  molecules called exopolysaccharides, which provide structure to  biofilms that can surround a plant’s roots and keep them from losing water. You might think that these are just  all-purpose growth-promoting microbes, but that doesn’t seem to be the case. Under normal conditions, they don’t seem to do much for plant growth or crop yield.

They only start to do their  thing once droughts hit, and not all plants seem to have  these particular helpful friends. So scientists have been  trying to come up with ways to harness the powers of  drought-resisting microbiomes and turn them on more consistently,  especially for food-producing crops. In 2017, researchers in China took  bacteria from the leaves of a desert plant species that is super drought-resistant,  as you would expect a desert plant to be.

They added that bacteria to the soil  that they were growing wheat in, and after a few days to let  the bacteria get settled in, the researchers withheld water  from the plants for a full week. Even with these simulated drought conditions, wheat plants grown with the  bacteria had less leaf curling, longer roots and shoots, more chlorophyll  and sugars, and higher total weight, which the researchers took  as evidence that the bacteria was contributing to growth enhancement  and water stress tolerance. And in 2015, researchers in  Milan got similar results when they inoculated pepper plants with  bacteria from grapevine microbiomes.

Now, we’re not at the stage of large-scale  deployment of plant microbiomes yet, but it’s an incredibly promising approach. The idea is that these microbes could  just be added to fertilizer or to soil. Smaller farms and those in developing  parts of the world would be able to use these solutions to improve  their yields and their livelihoods.

Which would mean that one answer to a super big problem could actually be super tiny. Thanks to our patrons on Patreon for  making videos like this one possible. Just like a community of microbes helping crops, our patrons are a community  of supporters that help us keep the lights on by surrounding  us with a really sticky biofilm.

And it’s not just selflessness -  you can get some pretty sweet perks for being a patron, like our  patron-exclusive podcast, and access to our private Discord server. If you’re interested in learning  more about becoming a patron, head over to Patreon.com/scishow. Thanks for learning with us and for watching! [♪ OUTRO]