Bacterial leaf blight is a major disease of eucalypt, especially under nursery conditions. Different bacterial species have been associated with the disease in several countries, and despite its importance worldwide, it is not clear to date whether similar disease symptoms are caused by the same or by different etiological agents. In this study, 43 bacterial strains were isolated from blighted eucalypt leaves collected in different geographic areas of Brazil and inoculated onto a susceptible eucalypt clone. Polyphasic taxonomy, including morphological, physiological, biochemical, molecular, and pathogenicity tests showed that only certain strains of Xanthomonas axonopodis caused symptoms of the disease. Strains varied in their aggressiveness, but no correlation with geographic origin was observed. MLSA-based phylogenetic analysis using concatenated dnaK, fyuA, gyrB and rpoD gene sequences allocated the strains in a well-defined clade, corresponding to Rade-marker's group RG 9.6. Inoculation of nineteen plant species belonging to seven botanical families with representative strain LPF 602 showed it to be pathogenic only on Eucalyptus spp, and Corymbia spp. Based on distinct biochemical and pathogenic characteristics that differentiate the eucalypt strains from other pathovars of the X. axonopodis species, here we propose their allocation into the new pathovar X. axonopodis pv. eucalyptorum pv. nov.

中文翻译：

---

轴毛黄单胞菌 pv. 桉树PV. 十一月 在巴西引起桉树细菌性叶枯病。

细菌性叶枯病是桉树的主要病害，尤其是在苗圃条件下。在多个国家，不同的细菌种类与该疾病有关，尽管其在世界范围内很重要，但迄今为止尚不清楚类似的疾病症状是由相同还是不同的病原体引起。在这项研究中，从巴西不同地理区域收集的枯萎桉树叶中分离出 43 株细菌菌株，并将其接种到易感桉树克隆上。多相分类学，包括形态学、生理学、生化、分子和致病性测试表明，只有某些Xanthomonas axonopodis菌株会引起该疾病的症状。菌株的攻击性各不相同，但没有观察到与地理起源的相关性。使用串联的dnaK、fyuA、gyrB和rpoD基因序列进行基于 MLSA 的系统发育分析，将菌株分配到明确的进化枝中，对应于 Rade-marker 的组 RG 9.6。用代表性菌株 LPF 602 接种属于 7 个植物科的 19 种植物，结果表明该菌株仅对桉树属和伞房属属致病。基于区分桉树菌株与X. axonopodis物种其他致病变种的独特生化和致病特征，我们在此建议将其分配到新的致病变种X. axonopodis pv. 中。桉树PV. 十一月