Characterization and Genomic Analysis of Rahnella aceris Associated With Postharvest Rot in Pear

Fruit rot symptoms were observed in D'Anjou pears ( Pyrus communis ) in Alto Valle, Río Negro, Argentina, over two postharvest seasons (2024 and 2025), affecting fruits from six orchards during cold storage. Affected fruits developed brown, soft, circular lesions that progressed into the pulp, accompanied by translucent halos. Bacterial isolates from symptomatic tissue reproduced rot symptoms in inoculated pears, and pathogenicity tests confirmed the susceptibility of D'Anjou, Packham's Triumph, Williams and Abate Fetel cultivars. Whole‐genome sequencing of a representative strain using Oxford Nanopore Technologies (ONT) identified it as Rahnella aceris (99.18% ANI; > 94% dDDH vs. type strain SAP‐19). This is the first report of R. aceris associated with postharvest pear rot, highlighting the need for further research on its association with pome fruits.