Engineering Plants to Fight Disease with Friendly Bacteria

For the first time, scientists have modified the plant microbiome to increase the amount of “good” bacteria that shield the plant from harm.

Researchers from the University of Southampton, China, and Austria have published their findings in Nature Communications, which have the potential to significantly lessen the need for pesticides that harm the environment.

The importance of the microbiome - the diverse range of microorganisms that inhabit and surround human bodies, chiefly in the digestive tracts - is becoming increasingly recognized by the general public. The immune system, metabolism, mood, and even the risk of illness are all impacted by the gut microbiomes.

Numerous different types of bacteria, fungi, viruses, and other microorganisms can be found living in the roots, stems, and leaves of plants. Scientists have been studying plant microbiomes extensively for the past 10 years in an effort to better understand how they impact a plant's health and susceptibility to disease.

For the first time, we’ve been able to change the makeup of a plant’s microbiome in a targeted way, boosting the numbers of beneficial bacteria that can protect the plant from other, harmful bacteria.”

Dr. Tomislav Cernava, Study Co-Author and, Associate Professor, Plant-Microbe Interactions, University of Southampton

Cernava continues, “This breakthrough could reduce reliance on pesticides, which are harmful to the environment. We’ve achieved this in rice crops, but the framework we’ve created could be applied to other plants and unlock other opportunities to improve their microbiome. For example, microbes that increase nutrient provision to crops could reduce the need for synthetic fertilizers.”

The multinational research team found that the rice plant’s microbiome is shaped by a single gene located in the lignin biosynthesis cluster. Plant cell walls contain lignin, a complex polymer that makes up more than 30% of the biomass in some plant species.

First, the scientists saw a drop in the number of specific beneficial bacteria when this gene was turned off, indicating the significance of this gene in the composition of the microbiome community.

Subsequently, the scientists overexpressed the gene to increase the production of a particular kind of metabolite, which is a tiny molecule generated by the host plant as part of its metabolic processes. As a result, the plant microbiome's beneficial bacteria proportion rose.

Compared to wild-type rice, these engineered plants showed a significant increase in resistance against Xanthomonas oryzae, a pathogen that causes bacterial blight in rice crops.

In Asia, bacterial blight is frequent and can cause a significant reduction in rice yields. Since polluting pesticides are typically used to control it, cultivating a crop with a protective microbiome could improve both food security and the environment.

The research team is currently investigating how they can unlock different plant health benefits by influencing the presence of other beneficial microbes.