Why Microbes Perform Under Stress

By Geoffrey von Maltzahn

This past season, we planted Indigo Corn™ in a region of central Kansas where fields only received 50% of their average rainfall. This severe water stress led to yields of only 80 bushels per acre on many farms. With Indigo Corn, yield increases of 32 to 40 bushels an acre were seen, despite the conditions. As our CEO, David Perry, pointed out, this meaningful boost could account for the profitability of a family farm.

Under near-optimal growing conditions in the Mid-south, Indigo Corn performed similarly to the control (corn grown from seeds without microbial treatment). With field data like this, we’re often asked, “How can your products deliver such significant results under stress?” The answer lies in the science behind microbes, how they perform, and their essential relationship with plants.

First, it’s important to know where our microbes come from. We isolate our microbes from inside of healthy plants. Not from the soil. And not from the surfaces of plants. This means that our microbes have been naturally invited by that plant to live inside its tissues and become a part of its internal biology and metabolism. Indigo has been a leader in discovering that these special microbes — endophytes — can play vital roles in helping crops survive a wide range of stresses. After all, because the crop is their host ­­— their home — they are motivated to do anything they can to ensure its health.

A characteristic of natural microbes that makes them more powerful than traditional crop technologies like chemistries and GMOs is their ability to respond rapidly to their environment. Whether it’s cool, hot, wet, or dry, they respond. And they do so within seconds. This makes microbes nimble, in a way that non-living technologies, such as synthetic fertilizers and chemicals, are not. Their responsiveness is their asset, and makes them a dynamic partner to plants during the constantly varying stresses experienced during the year: microbes are tuning their responses to the needs of each plant in a field, every minute, every day. Farmers know the importance of this, as stresses can vary dramatically across even one single acre and within a few days.

Corn — and its microbiomes — have changed a lot since plant breeding began. We’ve bred corn over millennia to grow quickly while producing enormous yields in just three months. The ancestor of corn, teosinte, evolved in Mexico as perennial to survive stimuli such as 100 degree heat. Corn lost that ability when humans bred it to live as an annual in northern climates. When a crop can’t respond to stresses such as drought, heat, or nutrient limitation at critical stages in development, yields are massively impacted. In corn, it’s critical for seedlings to have enough water to get them up and growing. At florescence, it needs to be cool enough that the silks can fully develop. During grain fill, the crop needs enough water to be able to move nutrients. Throughout the full season, too, the crop needs a big enough root structure to pull in water, nitrogen, and micronutrients that promote growth. These stages present an acute need for the plant to pass a certain threshold. If it doesn’t, yield suffers. If it does, then bushel jumps come easily. Here, microbes come dramatically into play. As living organisms, they can respond to the environment, giving plants at shot at maintaining performance. The microbes that we’re working with take on stress, while corn continues to develop and reproduce. And because these microbes live inside of plants, they are in an ideal position to help the plant when stresses do arise. Living, changeable, and responsive, microbes are aware of stresses that we’re not.

The responsiveness of our microbes also underpins the ability of Indigo Corn to maintain optimal yield under high yield (low stress) conditions. When there isn’t stress, the crop develops and yields as normal — providing growers with optimal performance under optimal conditions. This contrasts with GMO approaches to drought protection, which have offered modest protection under high water stress at the cost of significant yield drag under normal yielding conditions. This tradeoff makes it hard for farmers to benefit. Indigo Corn offers improved yield under water stress, without tradeoffs.

New approaches (like Indigo Corn) to naturally managing environmental stress without tradeoffs can have enormous benefits for farmers. Taking water stress alone, the annual yields of unirrigated acres of corn, wheat, soy, and cotton in the US are ~40% lower than irrigated acres — and nearly 90% of each of those crops are non-irrigated. This creates an extraordinary need for effective solutions that can make crops healthier under water stress every year, and sustain both crops and growers in bad years.

We’re proud of what we’re doing at Indigo, and know we are still just scratching the surface of what the microbiome can provide to modern agriculture. Teosinte, corn’s ancestor, has a hugely diverse microbiome. It’s also a straggly plant with small fruit. We’ve since taken it and bred a tall stalk and gigantic ear with a phenomenal potential to feed people. The environment of modern corn, though, is not nearly as rich. Agricultural chemicals, particularly fungicides, have diminished plant and soil microbiomes, as has the limited diversity of what we plant. At Indigo, we’re working to restore that microbiome, giving crops what they need to respond to their environment.