Characterization of the Xylella fastidiosa PD1311 gene mutant and its suppression of Pierce's disease on grapevines

Abstract

Xylella fastidiosa causes Pierce's disease (PD) on grapevines, leading to significant economic losses in grape and wine production. To further our understanding of X. fastidiosa virulence on grapevines, we examined the PD1311 gene, which encodes a putative acyl-coenzyme A (acyl-CoA) synthetase, and is highly conserved across Xylella species. It was determined that PD1311 is required for virulence, as the deletion mutant, ΔPD1311, was unable to cause disease on grapevines. The ΔPD1311 strain was impaired in behaviours known to be associated with PD development, including motility, aggregation and biofilm formation. ΔPD1311 also expressed enhanced sensitivity to H O and polymyxin B, and showed reduced survival in grapevine sap, when compared with wild-type X. fastidiosa Temecula 1 (TM1). Following inoculation, ΔPD1311 could not be detected in grape shoots, which may be related to its altered growth and sensitivity phenotypes. Inoculation with ΔPD1311 2 weeks prior to TM1 prevented the development of PD in a significant fraction of vines and eliminated detectable levels of TM1. In contrast, vines inoculated simultaneously with TM1 and ΔPD1311 developed disease at the same level as TM1 alone. In these vines, TM1 populations were distributed similarly to populations in TM1-only inoculated plants. These findings suggest that, through an indirect mechanism, pretreatment of vines with ΔPD1311 suppresses pathogen population and disease.

From Nucleotides to Satellite Imagery: Approaches to Identify and Manage the Invasive Pathogen Xylella fastidiosa and Its Insect Vectors in Europe

“…Recent developments have optimized robustness, efficiency and time effectiveness of genetic manipulation protocols [171]. Successful studies involving comparisons of wild-type and overexpressed or knocked-out Xf mutants and complementation analyses have clarified the mechanisms underlying virulence or host specificity and helped characterizing the function of unknown genetic elements [171,175,177,[180][181][182][183][184]. Some transgenic organisms were created for practical applications such as disease suppression, including a genetically modified Xf avirulent strain [180,185].…”

Effectiveness of in planta control measures for Xylella fastidiosa

“…Virulence to grape of X. fastidiosa strains originally obtained from grapevines with Pierce's disease varies from avirulent to highly virulent. Weakly virulent strains multiply and move systemically but more slowly in the plant, producing only minor symptoms in the host (Hopkins, ; Hao et al., ). Several experimental studies were conducted to assess whether an inoculation of avirulent/weakly avirulent strains of X. fastidiosa in grapevines could provide protection against Pierce's disease.…”

The great potential of entomopathogenic bacteria Xenorhabdus and Photorhabdus for mosquito control: a review

“…Chemical control may have disadvantages, such as effects on non-target organisms, environmental pollution, in addition to the development of insecticide resistance [27,[39][40][41][42][43]. Furthermore, repeated doses and high doses of chemical insecticides can cause an imbalance between the culicid population and their natural enemies, and also cause toxic effects on the environment and small mammals that co-inhabit the surrounding area [40].…”