In the shadowy world of plant pathogens, a new stealthy tactic has been uncovered, one that could reshape our understanding of crop protection and potentially bolster food security. Researchers from the Technical University of Denmark have identified a unique enzymatic mechanism used by Phytophthora, a genus of oomycete pathogens, to silently invade plants. This discovery, led by Simone Turella from the Department of Biotechnology and Biomedicine, could open new avenues for developing innovative bioprotection strategies.
Phytophthora species are notorious for causing devastating crop losses, affecting everything from potatoes to soybeans. These pathogens secrete proteins that interact with plant hosts, but many of these interactions remain shrouded in mystery. Turella and her team have lifted a corner of the veil, revealing a previously unknown microbial mechanism that helps these pathogens evade plant immune responses.
At the heart of this discovery are enzymes known as auxiliary activity family 7 (AA7) oxidases. These enzymes, found in both Ascomycota and Oomycota phytopathogens, have a unique ability to oxidize pectin-derived galacturonic acid and oligogalacturonides (OGs). Pectin is a crucial component of plant cell walls, and its breakdown products, like OGs, typically trigger plant immune responses. However, the AA7 enzymes seem to have found a way to turn off these alarm signals.
“The oxidation of OGs by these enzymes impairs their elicitor activity,” explains Turella. “This means the plant’s immune system doesn’t recognize the pathogen as effectively, allowing it to infiltrate and cause damage more stealthily.”
The researchers found that Phytophthora sojae, a particularly devastating pathogen for soybeans, produces unique mono-cysteinyl-FAD oxidases with positively-charged active sites. These enzymes are particularly well-suited to oxidize OGs. Moreover, the genes encoding these OG oxidases are co-transcribed with pectin-degradation counterparts during the early stages of infection, suggesting a coordinated effort to suppress the plant’s defenses.
To test the importance of these OG oxidases, the team created single knockouts of the oxidase genes in P. sojae. The results were striking: the knockouts significantly decreased the pathogen’s biomass in planta, linking these oxidases to virulence.
This research, published in Nature Communications, translates to “Nature Communications” in English, sheds light on a novel microbial strategy that could have significant implications for crop protection. By understanding how these pathogens evade plant immune responses, researchers can develop targeted bioprotection strategies. This could lead to more effective and sustainable crop protection methods, ultimately enhancing food security.
The discovery of these unique oxidases also opens up new possibilities for biotechnological applications. For instance, these enzymes could be engineered to enhance plant resistance to pathogens, or even to develop new types of bio-based pesticides that specifically target these stealthy invaders.
As Turella puts it, “This is just the beginning. There’s so much more to explore in this area. The more we understand about these pathogens’ strategies, the better equipped we’ll be to protect our crops and ensure food security.”
This research is a testament to the power of fundamental science in driving innovation. By unraveling the intricate mechanisms of plant-pathogen interactions, we can pave the way for a more secure and sustainable future in agriculture. The implications extend beyond the farm, potentially influencing the energy sector as well. Many bioenergy crops, such as switchgrass and miscanthus, are also susceptible to Phytophthora infections. Protecting these crops could enhance bioenergy production, contributing to a more sustainable energy mix.
As we stand on the brink of a new era in crop protection, this discovery serves as a reminder of the power of curiosity-driven research. It’s a call to action for scientists, farmers, and policymakers alike to invest in and champion such research, for the sake of our food security and our planet’s future.