Differentiation in MALDI-TOF MS and FTIR spectra between two pathovars of Xanthomonas oryzae

•MALDI-TOF MS revealed the difference between two pathovars of Xanthomonas oryzae.•FTIR spectra revealed the difference between two pathovars of Xanthomonas oryzae.•MALDI-TOF MS and FTIR spectra could differentiate two pathovars of X. oryzae.

Xanthomonas oryzae pv. oryzae (Xoo) and Xanthomonas oryzae pv. oryzicola (Xoc) strains are closely related phenotypically and genetically, which make it difficult to differentiate between the two pathovars based on phenotypic and DNA-based methods. In this study, a fast and accurate method was developed based on the differences in MALDI-TOF MS and FTIR spectra between the two pathovars. MALDI-TOF MS analysis revealed that 9 and 10 peaks are specific to Xoo and Xoc, respectively, which can be used as biomarkers to identify and differentiate the two closely related pathovars. Furthermore, FTIR analysis showed that there is a significant difference in both the band frequencies and absorption intensity of various functional groups between the two pathovars. In particular, the 6 peaks at 3433, 2867, 1273, 1065, 983 and 951 cm−1 were specific to the Xoo strains, while one peak at 1572 cm−1 was specific to the Xoc strains. Overall, this study gives the first attempt to identify and differentiate the two pathovars of X. oryzae based on mass and FTIR spectra, which will be helpful for the early detection and prevention of the two rice diseases caused by both X. oryzae pathovars.

Graphical abstractMALDI-TOF MS protein mass fingerprint of (a) Xanthomonas oryzae pv. oryzicola and (b) Xanthomonas oryzae pv. oryzae. Similar and different marker masses for the identification of (a) and (b) are listed in Table 2. Intensity of ions is shown on the Y axis and the mass (in Daltons) of the ions is shown on the X axis. The m/z values represent mass to charge ratios. The unique peaks positions are marked for each of species in Fig. 1.Figure optionsDownload full-size imageDownload as PowerPoint slide