Laboratory of Gene Technology, Department of Biosystems, KU Leuven, Kasteelpark Arenberg 21 box 2462, 3001 Heverlee, Belgium.
Department of Crop Protection, Institute for Agricultural and Fisheries Research, Burg. Van Gansberghelaan 96, 9820 Merelbeke, Belgium.
Int J Mol Sci. 2020 Apr 22;21(8):2930. doi: 10.3390/ijms21082930.
The prevalence of pv. (Pspo) in Belgium continues to increase and sustainable treatments for this pathogen remain unavailable. A potentially attractive biocontrol strategy would be the application of bacteriophages. The ideal application strategy of phages in an agricultural setting remains unclear, especially in a field-based production such as for leek plants in Flanders. Therefore, more insight in bacteria-phage interaction is required, along with the evaluation of different application strategies. In this study, we further characterized the infection strategy of two Pspo phages, KIL3b and KIL5. We found that both phages recognize lipopolysaccharide (LPS) moieties on the surface of the bacterium. LPS is an important pathogenicity factor of Pspo. Our data also suggest that KIL5 requires an additional protein in the bacterial cytoplasmatic membrane to efficiently infect its host. Virulence tests showed that this protein also contributes to Pspo virulence. Furthermore, a cocktail of both phages was applied in a seed bioassay. A combination of KIL3b and KIL5 reduced the bacterial concentration 100-fold. However, in vitro Pspo resistance against phage infection developed quite rapidly. However, the impact of this phage resistance might be mitigated as is suggested by the fact that those resistance mutations preferably occur in genes involved in LPS metabolism, and that the virulence of those mutants is possibly reduced. Our data suggest that the phage cocktail has promising potential to lower the prevalence of Pspo and to be integrated in a pest management strategy. Targeted research is needed to further explore the applicability of the phages in combination with other disease control strategies.
PV 的流行率在比利时继续增加，而针对这种病原体的可持续治疗方法仍然缺乏。一种潜在的有吸引力的生物防治策略将是噬菌体的应用。噬菌体在农业环境中的理想应用策略仍不清楚，特别是在像佛兰德斯韭菜这样的田间生产中。因此，需要更多地了解细菌-噬菌体的相互作用，并评估不同的应用策略。在这项研究中，我们进一步描述了两种 Pspo 噬菌体 KIL3b 和 KIL5 的感染策略。我们发现这两种噬菌体都能识别细菌表面的脂多糖（LPS）部分。LPS 是 Pspo 的一个重要致病性因素。我们的数据还表明，KIL5 需要在细菌细胞质膜中额外的蛋白质才能有效地感染其宿主。毒性试验表明，这种蛋白质也有助于 Pspo 的毒性。此外，将两种噬菌体的混合物应用于种子生物测定中。KIL3b 和 KIL5 的混合物将细菌浓度降低了 100 倍。然而，噬菌体感染的体外 Pspo 抗性发展得相当快。然而，噬菌体抗性的影响可能会减轻，这是因为这些抗性突变主要发生在参与 LPS 代谢的基因中，而且这些突变体的毒性可能降低。我们的数据表明，噬菌体混合物具有降低 Pspo 流行率并整合到害虫管理策略中的潜力。需要有针对性的研究来进一步探索噬菌体与其他疾病控制策略结合的适用性。
