Nicotiana tabacum and Vitis vinifera as suitable growth-chamber models for microinjection-based studies of Xylella fastidiosa

Xylella fastidiosa is one of the most important plant pathogens worldwide, infecting more than 700 plant species and causing major economic losses in affected agricultural regions. In the absence effective curative treatments under field conditions, experimental research is essential. However, research efforts are severely constrained by strict phytosanitary regulations and the pathogen's restricted geographic distribution, as well as its demanding culture requirements. To the best of our knowledge, no studies have compared different host infection models under controlled growth-chamber conditions. To address these limitations, we developed and compared a microinjection-based inoculation protocol across herbaceous and woody hosts maintained in biosafety growth chambers. Stems of Vitis vinifera, Nicotiana tabacum, N. benthamiana, and Medicago sativa were inoculated with X. fastidiosa by microinjection and maintained under controlled growth-chamber conditions. Pathogen establishment was assessed by qPCR analysis of petiole tissue, together with disease progression, plant growth, and leaf scorch development. Approximately one month after inoculation, bacterial detection rates reached 100% in V. vinifera and 80% in N. tabacum. Both species subsequently exhibited measurable disease development, whereas bacterial establishment and phenotypic responses were less consistent in N. benthamiana and M. sativa.