PDF(Pubmed)
Abstract：
In Florida, angular leaf spot, caused by Xanthomonas fragariae, was the only known bacterial disease in strawberry, which is sporadic and affects the foliage and calyx. However, from the 2019-2020 to 2023-2024 Florida strawberry seasons, unusual bacterial-like symptoms were observed in commercial farms, with reports of up to 30 % disease incidence. Typical lesions were water-soaked and angular in early stages that later became necrotic with a circular-ellipsoidal purple halo, and consistently yielded colonies resembling Pseudomonas on culture media. Strains were pathogenic on strawberry, fluorescent, oxidase- and arginine-dihydrolase-negative, elicited a hypersensitive reaction on tobacco, and lacked pectolytic activity. Although phenotypic assays, such as fatty acid methyl profiles and Biolog protocols, placed the strains into the Pseudomonas group, there was a low similarity at the species level. Further analysis using 16S rRNA genes, housekeeping genes, and whole genome sequencing showed that the strains cluster into the Pseudomonas group but do not share more than 95 % average nucleotide identity compared to representative members. Therefore, the genomic and phenotypic analysis confirm that the strains causing bacterial spot in strawberry represent a new plant pathogenic bacterial species for which we propose the name Pseudomonas fragariae sp. nov. with 20-417T (17T=LMG 32456T=DSM 113340 T) as the type strain, in relation to Fragaria×ananassa, the plant species from which the pathogen was first isolated. Future work is needed to assess the epidemiology, cultivar susceptibility, chemical sensitivity, and disease management of this possible new emerging strawberry pathogen.
摘要：
在佛罗里达,角状叶斑,由脆弱黄单胞菌引起的，是草莓中唯一已知的细菌性疾病，这是零星的，影响叶子和花萼。然而,从2019-2020年到2023-2024年佛罗里达草莓季节，在商业农场中观察到异常的细菌样症状，报告高达30%的疾病发病率。典型的病变在早期阶段是浸水和角状的，后来变成坏死，带有圆形椭圆形的紫色光环，并且在培养基上始终产生类似假单胞菌的菌落。菌株对草莓有致病性，荧光，氧化酶和精氨酸双水解酶阴性，引起烟草的过敏反应，缺乏果胶活性。虽然表型测定，例如脂肪酸甲基谱和Biolog协议，将菌株放入假单胞菌群，物种水平的相似性较低。使用16SrRNA基因进行进一步分析，管家基因,和全基因组测序表明，这些菌株聚集到假单胞菌组中，但与代表性成员相比，平均核苷酸同一性不超过95％。因此,基因组和表型分析证实，在草莓中引起细菌斑点的菌株代表了一种新的植物病原菌种，我们建议将其命名为假单胞菌。11月。以20-417T(17T=LMG32456T=DSM113340T)为应变型,关于Fragaria×ananassa，首先分离出病原体的植物物种。未来的工作需要评估流行病学，品种敏感性，化学灵敏度,以及这种可能的新出现的草莓病原体的疾病管理。
