Molecular, Phenotypical, and Host-Range Characterization of Robbsia andropogonis Strains Isolated from Bougainvillea spp. in Mexico.

Characteristic leaf spot and blight symptoms caused by Robbsia andropogonis on bougainvillea plants were found in three locations in different provinces of Mexico from 2019 to 2020. Eleven bacterial isolates with morphology similar to R. andropogonis were obtained from the diseased bougainvillea leaves. The isolates were confirmed as R. andropogonis by phenotypic tests and 16S rRNA, rpoD, and gyrB gene sequencing. In addition to bougainvillea, the strains were pathogenic to 10 agriculturally significant crops, including maize (Zea mays), sorghum (Sorghum bicolor), barley (Hordeum vulgare), coffee (Coffea arabiga), carnation (Dianthus caryophilus), Mexican lime (Citrus × aurantifolia), common bean (Phaseolus vulgaris), broadbeans (Vicia faba), and pea (Pisum sativum), but not runner bean (Phaseolus coccineus). The haplotypes network reveals the genetic variability among Mexican strains and its phylogeographic relationship with Japan, the U.S.A., and China. The presence of this pathogen represents a challenge for plant protection strategies in Mexico.