Now this is interesting - corn

From The Atlantic:

The Wonder Plant That Could Slash Fertilizer Use
For thousands of years, people from Sierra Mixe, a mountainous region in southern Mexico, have been cultivating an unusual variety of giant corn. They grow the crop on soils that are poor in nitrogen—an essential nutrient—and they barely use any additional fertilizer. And yet, their corn towers over conventional varieties, reaching heights of more than 16 feet.

A team of researchers led by Alan Bennett from UC Davis has shown that the secret of the corn’s success lies in its aerial roots—necklaces of finger-sized, rhubarb-red tubes that encircle the stem. These roots drip with a thick, clear, glistening mucus that’s loaded with bacteria. Thanks to these microbes, the corn can fertilize itself by pulling nitrogen directly from the surrounding air.

The Sierra Mixe corn takes eight months to mature—too long to make it commercially useful. But if its remarkable ability could be bred into conventional corn, which matures in just three months, it would be an agricultural game changer.

What a wonderful example of mutualism - the bacteria get their own little environment and the corn plant gets its nitrogen. They did this ethically too - nice touch:

Crucially, the Davis team involved the Sierra Mixe community throughout their research. They also established legal agreements with the Mexican government to ensure that any benefits from their research—and its subsequent commercialization—would be shared with the community, under the auspices of the Nagoya Protocol, an international framework intended to thwart bio-piracy. Alejandra Barrios, the director of biosafety and biodiversity at Mexico’s environmental agency, repeatedly praised the approach on Twitter, calling it “great work” and a “win-win solution.”

This discovery has wide-ranging inmplications for other crops as well. Nitrogen is a key element for plant growth (along with CO2)