{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,23]],"date-time":"2026-02-23T17:22:50Z","timestamp":1771867370742,"version":"3.50.1"},"posted":{"date-parts":[[2026]]},"group-title":"SSRN","reference-count":0,"publisher":"Elsevier BV","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:p>Erwinia amylovora, the causal agent of fire blight, continues to pose a significant threat to the production of pome fruits. This study analyzed a recent Portuguese collection (n=111; 2023\u20132024, Oeste region), combining CRISPR-based lineage typing with virulence assays and antimicrobial susceptibility benchmarking. CRISPR-PCR at the CR1 locus revealed two co-circulating global lineages: the D-derived genotype was predominant (80.2%) across hosts and municipalities, whereas the A-derived genotype, which was present at a lower frequency (19.8%), was geographically concentrated in the central pear belt. The A- genotype proportion increased from 10% in 2023 to 21.3% in 2024, possibly due to broader sampling. Virulence was heterogeneous and independent of CR1 genotype. All tested isolates were pathogenic, with lesion areas at 6 dpi ranging from 20 \u00b1 3.27 to 254 \u00b1 89.17 mm2. D-genotype strains exhibited a wide range of aggressiveness, including isolates comparable to the highly virulent reference strain CFBP 1430. Although all isolates were inhibited by oxytetracycline, susceptibility testing showed high-level streptomycin resistance in 3% of the population. Copper-based products showed variable and frequently weak in vitro inhibition. In contrast, biological agents, namely Bacillus amyloliquefaciens and the newly isolated lytic bacteriophage Prophecy, exhibited broad activity across both genotypes (&gt;96%). Taken together, these data reveal a rising A-subpopulation, substantial genotype-independent virulence heterogeneity, and the superior in vitro performance of biologicals over conventional copper agents. These results provide a baseline for integrated fire blight management in Portugal and support the development of phage-based tools alongside whole-genome surveillance to track pathogen diversification.<\/jats:p>","DOI":"10.2139\/ssrn.6278649","type":"posted-content","created":{"date-parts":[[2026,2,23]],"date-time":"2026-02-23T16:46:09Z","timestamp":1771865169000},"source":"Crossref","is-referenced-by-count":0,"title":["Comparative Evaluation of the profiles of Portuguese Erwinia amylovora strains regarding CRISPR and Conventional and Emerging Control Agents"],"prefix":"10.2139","author":[{"given":"Carlos","family":"Rodrigues","sequence":"first","affiliation":[]},{"given":"Gabriel","family":"Abreu","sequence":"additional","affiliation":[]},{"given":"Daniel","family":"McGuire","sequence":"additional","affiliation":[]},{"given":"Guilherme","family":"Gomes","sequence":"additional","affiliation":[]},{"given":"Carolina","family":"Ferreira","sequence":"additional","affiliation":[]},{"given":"Daniela","family":"Ara\u00fajo","sequence":"additional","affiliation":[]},{"given":"Joana","family":"Castro","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0175-1119","authenticated-orcid":true,"given":"Carina","family":"Almeida","sequence":"additional","affiliation":[]},{"given":"Ana","family":"Oliveira","sequence":"additional","affiliation":[]},{"given":"An\u00edcia","family":"Gomes","sequence":"additional","affiliation":[]},{"given":"Rafael","family":"Mendes","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4129-6381","authenticated-orcid":true,"given":"Concei\u00e7\u00e3o","family":"Santos","sequence":"additional","affiliation":[]},{"given":"Miguel","family":"Le\u00e3o","sequence":"additional","affiliation":[]},{"given":"Lu\u00eds","family":"Carvalho","sequence":"additional","affiliation":[]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6465-081X","authenticated-orcid":true,"given":"Lu\u00edsa","family":"Moura","sequence":"additional","affiliation":[]},{"given":"Leonor","family":"Cruz","sequence":"additional","affiliation":[]},{"given":"Hugo","family":"Oliveira","sequence":"additional","affiliation":[]}],"member":"78","container-title":[],"original-title":[],"deposited":{"date-parts":[[2026,2,23]],"date-time":"2026-02-23T16:46:09Z","timestamp":1771865169000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.ssrn.com\/abstract=6278649"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026]]},"references-count":0,"URL":"https:\/\/doi.org\/10.2139\/ssrn.6278649","relation":{},"subject":[],"published":{"date-parts":[[2026]]},"subtype":"preprint"}}