Xylella arrived in Puglia with a coffee plant from Costa Rica: research on the killer of olive trees published in Nature

Xylella fastidiosa, the bacterium responsible for the destruction of olive trees, may have reached Puglia in 2008, transported by a coffee plant from Costa Rica. This hypothesis, described in the journal Nature, was formulated by researchers from the Institute for Sustainable Plant Protection at the National Research Council (Cnr-Ipsp), the University of Bari, the University of California at Berkeley and the University of Montpellier.

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by GIULIANO FOSCHINI



Xylella, the authors explain, is an invasive pathogen that can infect at least 595 plant species. This bacterium was discovered in 2013 and caused an epidemic among olive trees in Puglia and spread to France, Spain and Portugal. In fact, the pathogen causes the Rapid Olive Desiccation Complex (CoDiRO), which induces dryness of leaves and branches, up to the death of the plant.

“Unlike other bacteria – he says Maria SaponariCNR-Ipsp researcher and co-author of the article – Xylella fastidiosa is very difficult to extract and grow in vitro, so much so that at first it was difficult to determine the cause of plant death. “Between 2013 and 2017, researchers collected twig samples from more than 70 trees with CoDiRO, and used a new protocol to extract bacterial DNA from them.

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“A large number of differences found in the genetic sequences – comments the expert – indicate a greater risk of mutations, and therefore longer duration periods in the Italian vegetation”. The information obtained was compared with four Costa Rican coffee plant samples. The results, the authors report, support the idea that the pathogen that has spread to Italy comes from Central America. According to the researchers’ estimates, the bacterium could have reached Italian olive trees in 2008, which would be in line with the first reports of contaminated trees from local farmers, which occurred in 2010. The incubation period for the disease, researchers confirm, may in fact last more than 24 months.

“We have highlighted occasional but significant differences between the Costa Rican and Italian genomes,” concludes Saponari. “Bari area, but containment measures appear to be effective in reducing the transmission of the infection. Further research will be needed to better evaluate the dynamics of the spread of Xylella, but our study sheds new light on some of the mechanisms associated with this bacterium.”

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