The phylloplane is an important microbial habitat and a reservoir of organisms that affect plant health, both positively and negatively. Taphrina betulina is the causative agent of birch witches’ broom disease. Taphrina are dimorphic, invading theirs hosts in a filamentous form and residing in the host phyllosphere in their non-infectious yeast form. As such, they are widely accepted to be found a resident yeasts on their hosts, even on healthy tissues; however, there is little experimental data to support this. With the aim of exploring the local infection ecology of T. betulina, we had isolated yeasts from the phylloplane of birch, using three classes of samples; from infected symptom bearing leaves inside brooms, healthy leaves from branches away from brooms on broom bearing trees, and symptom-free leaves from symptom-free trees. Isolations yielded 224 yeast strains, representing 11 taxa, including T. betulina, which was the most common isolate and was found in all sample classes, including asymptomatic leaves. Genotyping with two genetic markers revealed genetic diversity among these T. betulina isolates, with seven distinct genotype differentiated by the markers used. Of the 57 T. betulina strains, 22 representative strains were selected for further studies and preliminarily characterized, revealing differences in size and the ability to produced compounds with activity to activate the signalling pathway for the plant hormone auxin.

中文翻译：

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Taphrina betulina 和其他寄居在 Betula pendula phylloplane 中的酵母菌的分离和表征

叶面是重要的微生物栖息地，也是对植物健康产生积极和消极影响的生物库。Taphrina betulina是桦树女巫扫帚病的病原体。Taphrina是二态性的，以丝状形式侵入宿主，并以非感染性酵母形式存在于宿主叶际。因此，人们普遍认为它们是宿主体内的常驻酵母，甚至在健康组织中也是如此。然而，几乎没有实验数据支持这一点。以探索白桦茸局部感染生态为目的，我们使用三类样品从桦树的叶面中分离出酵母菌；来自被感染的有症状的扫帚叶子，来自带扫帚树上的扫帚的树枝上的健康叶子，以及来自无症状树的无症状叶子。分离产生了 224 个酵母菌株，代表 11 个分类群，包括T. betulina，它是最常见的分离株，在所有样本类别中都有发现，包括无症状的叶子。使用两种遗传标记进行基因分型揭示了这些桦木分离株之间的遗传多样性，其中使用的标记区分了七种不同的基因型。57 T. betulina 菌株，选择了 22 个代表性菌株进行进一步研究和初步表征，揭示了大小的差异以及产生具有激活植物激素生长素信号通路活性的化合物的能力。