Occurrence of Pantoea anthophila Causing Rhizome Rot Disease of Banana in China

Résumé fourni par la source

Banana (genus Musa) is an economically important fruit crop. In January 2026, a rhizome rot disease was observed in a banana plantation in Nanning, Guangxi, China, affecting more than 10% of cultivated plants. Infected plants initially showed no obvious aboveground symptoms; however, yellow to brown water-soaked spots appeared on the rhizomes. In severe cases, plants exhibited stunting and leaf yellowing. The decay was confined to the rhizome and did not have a foul odor. To isolate the pathogen, diseased tissues (5 × 5 mm) were dissected and surface-sterilized with 75% ethanol (30 s) followed by 2% NaClO (2 min), then rinsed three times with sterile water. The sterilized tissue sections were soaked in 2 mL of sterile water and shaken in a vortexed oscillator for 5 min. The resulting suspension was streaked onto Luria-Bertani (LB) agar medium and incubated at 28°C for 24 h. Single colonies were subcultured three times to obtain pure cultures. From three plants collected from the field, 15 pure bacterial cultures with similar morphology were isolated. On LB agar plates, the colonies were yellow, mucoid, round, and raised. Two strains, designated Gxpan1 and Gxpan2, were selected for further analyses. The 16S rDNA gene were amplified using primer pair 27F/1492R (Frank et al. 2008), and the other five housekeeping genes, atpD, rpoB, rplB, pyrG, and leuS, were amplified using the specific primers provided by Brady et al. 2008 and Delétoile et al. 2009. Sequences were deposited in GenBank with accession numbers: PZ278615 and PZ278616 (16S), PZ285929 and PZ285930 (atpD), PZ285927 and PZ285928 (rpoB), PZ428044 and PZ428045(rplB), PZ428042 and PZ428043(pyrG), PZ428040 and PZ428041(leuS). BLASTn analysis of six genes showed 98.25-100% identity with reference sequences of the Pantoea anthophila type strain LMG 2558. A phylogenetic tree based on concatenated gene sequences constructed using maximum likelihood based on five housekeeping genes confirmed that Gxpan1 and Gxpan2 clustered with P. anthophila. For the pathogenicity test, 10 mL of strain Gxpan1 (10 8 CFU/mL was injected into rhizomes of six healthy, 3-month-old banana plants using a syringe; another six healthy control plants were injected with 10 mL of sterile water. Inoculated plants were moved to a greenhouse at 28-32°C. After 15 days, all inoculated plants showed symptoms identical to those observed in the field, while the control plants remained asymptomatic. Bacterial colonies were successfully re-isolated from symptomatic rhizomes and identified via morphological and molecular characterization, fulfilling Koch’s postulates. P. anthophila has been reported to cause soft rot disease in Clausena lansium (Zhou et al. 2015; He et al. 2023), and to shoot dieback disease in Ceylon ironwood in Malaysia (Johari et al. 2024). To our knowledge, this is the first report of rhizome rot disease of banana caused by P. anthophila in China. This finding broadens the host range of Pantoea anthophila and contributes to the understanding of its epidemiology and management.

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