Bacterial pathogens are major causes of crop diseases, leading to significant production losses. For instance, kiwifruit canker, caused by the phytopathogen Pseudomonas syringae pv. actinidiae (Psa), has posed a global challenge to kiwifruit production. Treatment with copper and antibiotics, whilst initially effective, is leading to the rise of bacterial resistance, requiring new biocontrol approaches. Previously, we isolated a group of closely related Psa phages with biocontrol potential, which represent environmentally sustainable antimicrobials. However, their deployment as antimicrobials requires further insight into their properties and infection strategy. Here, we provide an in-depth examination of the genome of ΦPsa374-like phages and show that they use lipopolysaccharides (LPS) as their main receptor. Through proteomics and cryo-electron microscopy of ΦPsa374, we revealed the structural proteome and that this phage possess a T = 9 capsid triangulation, unusual for myoviruses. Furthermore, we show that ΦPsa374 phage resistance arises in planta through mutations in a glycosyltransferase involved in LPS synthesis. Lastly, through in vitro evolution experiments we showed that phage resistance is overcome by mutations in a tail fibre and structural protein of unknown function in ΦPsa374. This study provides new insight into the properties of ΦPsa374-like phages that informs their use as antimicrobials against Psa.

中文翻译：

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脂多糖依赖性噬菌体感染假单胞菌植物病原体并可进化以逃避噬菌体抗性

细菌性病原体是作物病害的主要原因，会导致严重的生产损失。例如，由植物病原体Pseudomonas syringae pv 引起的奇异果溃疡病。猕猴桃( Psa ) 对奇异果生产构成了全球挑战。用铜和抗生素治疗虽然最初有效，但导致细菌耐药性上升，需要新的生物防治方法。此前，我们分离出一组密切相关的Psa具有生物防治潜力的噬菌体，代表环境可持续的抗菌剂。然而，它们作为抗菌剂的部署需要进一步了解它们的特性和感染策略。在这里，我们对 ΦPsa374 样噬菌体的基因组进行了深入检查，并表明它们使用脂多糖 (LPS) 作为主要受体。通过 ΦPsa374 的蛋白质组学和冷冻电子显微镜，我们揭示了结构蛋白质组，并且这种噬菌体具有T  = 9 衣壳三角剖分，这对于肌病毒来说是不寻常的。此外，我们表明 ΦPsa374 噬菌体抗性是通过参与 LPS 合成的糖基转移酶突变在植物中产生的。最后，通过体外进化实验表明，噬菌体抗性是通过 ΦPsa374 中尾纤维和功能未知的结构蛋白的突变来克服的。这项研究为 ΦPsa374 样噬菌体的特性提供了新的见解，这些特性有助于将它们用作抗Psa的抗菌剂。