Yu, H.; Li, Y.; Wu, H.; Gao, H.; Wang, H.; Liao, L.

Taro (Colocasia esculenta (L.) Schott) is an important vegetable and food crop in China, but soft rot disease has increasingly caused serious yield losses during cultivation. The disease damages corms and petiole bases, leading to tissue decay, foul odor, wilting, and lodging, resulting in significant economic loss and environmental concerns due to excessive pesticide use. Therefore, a green and efficient control strategy is urgently needed. In this study, a bacterial strain isolated from taro soft rot in Shaoguan, Guangdong, was identified as Pectobacterium colocasium ZXC0623. A lytic phage infecting this strain, named QJphage, was isolated and characterized for its physicochemical and biological properties, including optimal titer, latent period, multiplicity of infection, storage stability, and resistance to UV, pH, and chloroform. Bioinformatic analysis predicted eight tail fiber proteins as putative receptor-binding proteins (RBPs). Experimental validation using EGFP-tagged fusion expression followed by fluorescence microscopy confirmed that ORF04 functions as the functional RBP. Additionally, lipopolysaccharide (LPS) knockout mutants ({Delta}LPS1 and {Delta}LPS2) showed reduced plaque formation, indicating that LPS is an essential receptor for QJphage adsorption. Transcriptomic analysis during infection further suggested that pilin proteins may serve as reversible adsorption receptors, while the host strain possesses multiple anti-phage defense systems. Overall, QJphage exhibits stable properties and an LPS-dependent infection mechanism, providing a basis for phage-based control of taro soft rot.