Mass spectral analysis of pyoverdine purified from P. syringae 1448a. A. MALDI-TOF analysis showing three major [M+H]+ species. Ions corresponding to cyclic (m/z = 1123) and linear (m/z = 1141) pyoverdine are present along with a third variant species (m/z = 1212). B. MS/MS analysis of m/z = 1141 precursor; masses and putative identity of indicated peaks are presented in Table 3. C. MS/MS analysis of m/z = 1212 precursor showing a set of fragment ions 71 Da heavier than those indicated in part B (masses presented in Table 4).