A lipopolysaccharide-dependent phage infects a pseudomonad phytopathogen and can evolve to evade phage resistance.

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.

Genomes of Potato Mop-Top Virus (Virgaviridae: Pomovirus) Isolates from New Zealand and Their Impact on Diagnostic Methods.

Following the detection of potato mop-top virus (PMTV) in New Zealand in 2018, three near-complete PMTV genomes (AS22, AS99, AS144) were assembled from soil samples taken from potato fields in Canterbury. Phylogenetic analysis revealed that these genomes form a distinct lineage, with limited genetic diversity, within the PMTV species. This analysis supports the hypothesis that these genomes share a common origin, possibly resulting from a single (or limited) incursion of PMTV into New Zealand. A single nucleotide polymorphism was identified in the region where a key diagnostic primer binds. The mismatch of the diagnostic primer has implications for the effectiveness of the Mumford diagnostic protocol currently recommended for use in New Zealand; we recommend that the alternative Pandey assay, for which no primer mismatch was detected, be validated and optimized for use on the viral genomes present in New Zealand.

Draft Genome Sequence of a "Candidatus Liberibacter europaeus" Strain Assembled from Broom Psyllids (Arytainilla spartiophila) from New Zealand.

Here, we report the draft genome sequence of "Candidatus Liberibacter europaeus" ASNZ1, assembled from broom psyllids (Arytainilla spartiophila) from New Zealand. The assembly comprises 15 contigs, with a total length of 1.33 Mb and a G+C content of 33.5%.