Exploring the xylem-sap to unravel biological features of Xylella fastidiosa subspecies pauca ST53 in immune, resistant and susceptible crop species through metabolomics and in vitro studies

Antony Surano; Carmine Del Grosso; Biagia Musio; Stefano Todisco; Annalisa Giampetruzzi; Giuseppe Altamura; Maria Saponari; Vito Gallo; Piero Mastrorilli; Donato Boscia; Pasquale Saldarelli

doi:10.3389/fpls.2023.1343876

Exploring the xylem-sap to unravel biological features of Xylella fastidiosa subspecies pauca ST53 in immune, resistant and susceptible crop species through metabolomics and in vitro studies

Front Plant Sci. 2024 Jan 19:14:1343876. doi: 10.3389/fpls.2023.1343876. eCollection 2023.

Authors

Affiliations

¹ Institute for Sustainable Plant Protection, National Research Council (CNR), Bari, Italy.
² Department of Civil, Environmental, Land, Building Engineering and Chemistry (DICATECh), Polytechnic University of Bari, Bari, Italy.
³ CRSFA-Centro Ricerca, Sperimentazione e Formazione in Agricoltura Basile Caramia, Locorotondo, Italy.
⁴ Innovative Solutions S.r.l.-Spin-Off Company of Polytechnic University of Bari, Noci, Italy.

Abstract

Xylella fastidiosa subsp. pauca ST53 (Xfp) is a pathogenic bacterium causing one of the most severe plant diseases currently threatening the olive-growing areas of the Mediterranean, the Olive Quick Decline Syndrome (OQDS). The majority of the olive cultivars upon infections more or less rapidly develop severe desiccation phenomena, while few are resistant (e.g. Leccino and FS17), being less impacted by the infections. The present study contributes to elucidating the basis of the resistance phenomenon by investigating the influence of the composition of the xylem sap of plant species on the rate of bacterial multiplication. Xylem saps from Xfp host and non-host species were used for growing the bacterium in vitro, monitoring bacterial growth, biofilm formation, and the expression of specific genes. Moreover, species-specific metabolites, such as mannitol, quinic acid, tartaric acid, and choline were identified by non-targeted NMR-based metabolomic analysis in olive, grapevine, and citrus. In general, the xylem saps of immune species, including grapevine and citrus, were richer in amino acids, organic acids, and glucose. The results showed greater bacterial growth in the olive cultivar notoriously susceptible to Xfp (Cellina di Nardò), compared to that recorded in the resistant cultivar Leccino. Conversely, higher biofilm formation occurred in Leccino compared to Cellina di Nardò. Using the xylem saps of two Xfp-immune species (citrus and grapevine), a divergent bacterial behavior was recorded: low planktonic growth and biofilm production were detected in citrus compared to the grapevine. A parallel evaluation of the expression of 15 genes showed that Xfp directs its molecular functions mainly to virulence. Overall, the results gained through this multidisciplinary study contribute to extending the knowledge on the host-pathogen interaction, while confirming that the host response and resistance mechanism have a multifactorial basis, most likely with a cumulative effect on the phenotype.

Keywords: bacterial growth; biofilm formation; citrus; gene expression; grapevine; non-targeted NMR spectroscopy; olive; xylem-inhabiting pathogen.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was partially supported by the Ministero dell’agricoltura, della sovranità alimentare e delle foreste (DM n 664766 del 29/12/2022) in the framework of the Research Project OMIBREED ID07 “Caratterizzazione e valorizzazione dell’agrobiodiversità attraverso approcci multiomici e di next generation breeding per la resistenza a Xylella fastidiosa”.