Evaluation of an endophytic symbiont as biocontrol agent against Xylella fastidiosa CoDiRO

The quarantine bacterium Xylella fastidiosa is responsible for several diseases in a wide range of cultivated and wild plants. Few efforts have been made to investigate the potential use of endophytic symbionts on the disease phenotype of Xf-infected plants. The aim of our study is to evaluate if Paraburkholderia phytofirmans PsJN strain, a plant growth-promoting rhizobacterium, whose beneficial effects in reduction of symptom severity caused by Xf in grapevine affected by Pierce’s Disease have been recently proved, may play a role as biocontrol agent against Xf CoDiRO strain, that is causing in Apulia (Italy) a severe disease in olive groves. Greenhouse trials are being conducted to test the ability of P. phytofirmans to colonise xylem vessels of olive, Nicotiana benthamiana and oleander, following inoculation of bacterial suspensions by droplet puncture and root dipping. A conventional PCR assay for detection of P. phytofirmans movement in plants has been developed to be used in combination with plate isolation and an available qPCR specific assay. Preliminary results showed that needle-inoculated bacterial cells were detectable in the leaf petioles of the three hosts, distal from the inoculation site. Root dipping proved successful in infecting in vitro cultured olive plantlets. Double-infection assays, currently underway, will prove if P. phytofirmans PsJN shows a beneficial interaction with Xf CoDiRO.

This work received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 635646, POnTE (Pest Organisms Threatening Europe).

Published on October 20, 2017 by JOURNAL OF PLANT PATHOLOGY