Little is known about the epidemiology of the newly emerged disease on pistachio rootstock designated pistachio bushy top syndrome (PBTS). Here, we analysed the survival and colonization capacities of the two causative agents, Rhodococcus corynebacterioides‐like PBTS1 and R. fascians PBTS2, in the different habitats they occupy. Additionally, we examined their chromosomal sequences for genes that would support their ecology and provide experimental evidence for some of their predicted functions. We demonstrate that the soil competence of PBTS2 is better than that of PBTS1 and that both bacteria behave chemotactically, allowing them to translocate from soil to the rhizoplane. Once on the rhizoplane and the phylloplane, the PBTS bacteria form extensive epiphytic biofilms, probably aided by exopolysaccharide production. From these biofilms, the bacteria colonize the plant's interior tissues through the formation of ingression sites, likely created by the localized activity of cell wall‐degrading enzymes. The observed systemic spreading of the PBTS strains throughout the plant tissues is probably mediated by surface motility and agrees with the occurrence of symptoms in both the aerial and root parts of the plant host. Based on all available information, we provide a working model on this pathosystem to be used as a conceptual framework for future research.

中文翻译：

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红球菌生命多面性的殖民和生存能力。PBTS1和PBTS2

关于开心果砧木上新出现的这种疾病的流行病学知之甚少，这种开心果被称为开心果丛顶综合症（PBTS）。在这里，我们分析了两种病原体，如棒状红球菌PBTS1和R的存活和定植能力。法西斯人PBTS2，在它们所居住的不同栖息地中。此外，我们检查了它们的染色体序列中支持其生态学的基因，并为其某些预测功能提供了实验证据。我们证明了PBTS2的土壤能力比PBTS1更好，并且两种细菌都具有趋化性，从而使它们能够从土壤迁移到根际。PBTS细菌一旦在根际和叶状平面上，就形成广泛的附生生物膜，这可能是由于胞外多糖的产生所致。在这些生物膜中，细菌通过进入位点的形成而定居在植物的内部组织中，这可能是由于细胞壁降解酶的局部活性造成的。PBTS菌株在整个植物组织中的全身扩散可能是由表面运动介导的，并且与植物宿主的空中和根部的症状发生相吻合。基于所有可用信息，我们提供了此病理系统的工作模型，可用作将来研究的概念框架。