A small peptide stimulates almonds’ defense against devastating bacteria

Over the past decade, the lush olive groves one associates with the Italian countryside have dried up, as if trapped in perpetual winter. The culprit is Xylella fastidiosa, a species of aggressive bacteria that has caused devastating epidemics in several important crops. X. fastidiosa now threatens almonds, olives and vines, staples of Europe’s economy and cuisine.

There is currently no effective treatment for diseased almond trees infected by this bacterium, which has pushed researchers to develop and test new treatments. At the University of Girona, Spain, Luís Moll and Aina Baró, as well as collaborators from the Montesinos Laboratory, demonstrated that small peptides (molecules with a chain of up to 50 amino acids) are a promising treatment to prevent plant diseases induced by X fastidiosa, such as almond leaf scorch (ALS).

recently posted on plant pathology, their study tested the effects of a specific peptide, BP178, on ALS when administered to almond plants via endotherapy, which is similar to a plant vaccine. The authors found that the peptide has two functions for disease prevention: it can directly kill bacteria and it can trigger plant defense tactics. Corresponding author Prof. Emilio Montesinos comments: “We show that the treatment significantly reduces the pathogen population and disease symptoms and that it induces a strong defense response in almond plants.” The results agree with similar studies carried out by the researchers in other plants, such as the tomato.

This discovery represents a significant step in the fight against diseases caused by Xylella fastidiosa. According to the authors, the use of these compounds offers the possibility of sustainable crop protection and disease control, thanks to the biodegradability of the peptide and the low probability that bacteria will develop resistance to it. Although this study was conducted with plants in a greenhouse, it is expected that this peptide can be extended to nurseries and field use through commercial endotherapy systems and by optimizing the cost of producing the peptide for commercial use.

Furthermore, future studies may potentially generate new candidate compounds with the bifunctional action by changing the amino acid sequence to specifically target pathogens, which can be chemically synthesized or biotechnologically produced using microbial or plant biofactories.

Provided by the American Phytopathological Society