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Greenflies, locusts, and various insects aren’t the sole nuisances capable of rapidly decimating a harvest. Numerous detrimental bacteria have developed strategies to circumvent a plant’s defenses. A previously flourishing tomato plant can swiftly become unhealthy and mottled, due to tiny adversaries equipped with a range of tactics.
In a recent investigation, scholars at Washington University in St. Louis have discovered a mechanism that enables the bacteria Pseudomonas syringae to utilize a plant’s core biology against itself. The results, recently featured in the esteemed journal mBio, could eventually foster novel methods for safeguarding crops, noted co-author Barbara Kunkel, a professor of biology in Arts & Sciences. “If we can grasp the mechanism underlying the infection, we may strategically halt it,” she stated.
The primary author of the research is Chia-Yun “Cynthia” Lee, who was a graduate student in Kunkel’s laboratory during the study and is now a postdoctoral researcher in biology. Maya Irvine, an undergraduate research aide during the investigation, is another co-author.
Plant-associated bacteria are recognized for exploiting a vital plant hormone known as auxin, Kunkel noted. This hormone, present in all terrestrial plants from mosses to trees, serves multiple roles, including fostering growth and, importantly, managing environmental responses.
The WashU team theorizes that P. syringae and similar bacteria have discovered a mechanism to “listen” to the plant’s auxin signaling process. When the pathogens detect increased auxin production, they intensify their assault.
“The release of auxin signals the bacteria that their attack is effective, prompting them to proliferate and become even more hostile,” Kunkel explained. “It’s a cunning tactic to exploit and manipulate the plant’s biology.”
However, a crucial question lingered: How do bacteria detect a plant’s chemical signal? To address this, the WashU team meticulously examined the molecular and genetic machinery of P. syringae as it invaded thale cress (Arabidopsis thaliana), a member of the mustard family frequently studied at WashU and elsewhere. “We began searching for bacterial genes that might play a role in sensing auxin, and we identified a promising candidate,” Lee remarked.
The group pinpointed a specific protein termed PmeR, which appeared to meet the criteria. Not only could it perceive auxin — or, more precisely, a distinct compound related to auxin — but it also has the capability to activate particular genes in bacteria that enhance their aggression and virulence. “Once bacteria indirectly sense that auxin is present, they adjust their gene expression to optimize their survival within the plant,” Kunkel explained.
This understanding of the intricate communication between plants and their bacterial assailants may ultimately lead to innovative strategies for crop protection, Kunkel stated. There’s no straightforward method to target the PmeR protein in wild bacteria, nor can the essential hormone auxin be eliminated from tomatoes or any other plant. Nevertheless, another potential strategy might exist.
Kunkel’s team is collaborating with Joe Jez, the Spencer T. Olin Professor in Biology, to explore the possibility of rendering pathogenic bacteria “blind” to auxin.
“If we understood more about how bacteria perceive auxin, we could potentially create a compound that mimics auxin or auxin-related substances, confusing the bacteria and obstructing the system that renders them virulent,” Kunkel noted. “Perhaps we could spray fields with this substance.”
Before any such compound could come to fruition, researchers would need to gain a deeper understanding of the molecular structures involved. “That’s where Joe comes in,” Kunkel affirmed. “He possesses the tools and expertise to decipher even the most complex structures.”
Researchers remain far from halting P. syringae or other bacteria in their relentless pursuit of new plants to infect. However, grasping the mechanisms behind their attacks represents a significant and thrilling advancement, Lee said. “The dialogue between bacteria and plants is more intricate than we initially suspected, but we’re making headway.”
Originally published on the Ampersand website.
The post How harmful bacteria hijack crops first appeared on The Source.
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