UC Riverside study of combined species as root inoculants

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We all know that plants and microbes have an intricate relationship. This study uses combinations of a few strains to study the relationships. What do you think happened? Below are a few quotes.

A team led by scientists at the University of California, Riverside, set up experiments to answer these questions and better understand the competition process. The researchers used a native California plant with nodules, Acmispon strigosus, and a set of eight compatible nitrogen-fixing bacterial strains. They infected some plants with each of the eight strains to directly measure their ability to infect the plants and provide benefits. They then infected other plants with pairs of bacterial strains to assess the competitive ability of each strain and the effect on plant performance.

“To understand symbiosis, we often use sterile conditions where one strain of bacteria is ‘inoculated’ or introduced into an otherwise sterile host. Our experiments show that making that system slightly more complex—simply by using two bacterial strains at a time—fundamentally shifts the balance of benefits that the hosts receive, reshaping our understanding of how symbiosis works.” Joel Sachs said in the article.

“Sachs explained that a core challenge in agriculture is leveraging the services that microbes can provide to crops by promoting growth in a sustainable way, without the environmental costs of chemical fertilizers.”

“Ultimately, we want to use beneficial bacteria in agriculture,” he said. “To identify these bacteria, we would, typically, add one bacterial strain to a plant in the lab and show that the plant grows much better with the strain than without. In the field, however, that plant is covered in microbes, complicating the story. In our experiments, we advanced from using one strain to a pair of strains to see what impact that has on plant growth. Interestingly, with just two strains, many of our predictions fell apart.”

“It’s important, however, to keep in mind that bacteria are shaped by natural selection,” he said. “Some of them may be highly competitive in entering the nodule to infect the plant but not be very beneficial to the plant and that could be a trait that wins out in nature. If we are to leverage microbial communities for the services they can provide to plants and animals, we need to understand interstrain dynamics in these communities.”

PITTALWALA, IQBAL. Study improves understanding of how bacteria benefit plant growth: UC Riverside-led research aims to improve sustainable agricultural practices July 24, 2023. https://news.ucr.edu/articles/2023/07/24/study-improves-understanding-how-bacteria-benefit-plant-growth