支原体是细胞内致病菌,感染多种植物物种,包括重要农业作物和观赏树。然而,我们对症状严重程度之间关系的理解,疾病进展,由于无法将植物质机械接种到新的植物宿主中,因此植物质浓度仍然有限。本研究调查了长春花和番茄的植物血浆滴度动态和症状发展,两者都使用小型幼苗嫁接方法感染了相同的马铃薯紫顶(PPT)植浆菌株。绿化,Phyllody,和巫婆扫帚(WB)症状依次出现在长春花,而在番茄植物中,大芽(BB,一种叶状),花椰菜状花序(CLI),WB出现的顺序。从定量聚合酶链反应(qPCR)靶向PPT植原体的16SrRNA基因显示,在两个宿主物种,在不同的感染阶段,植物质滴度差异显着。值得注意的是,在显示叶状症状的样本中,观察到了最高的植物血浆浓度,而在西红柿中,滴度在BB阶段达到峰值。蛋白质印迹分析,利用对PPT植物浆特异的抗体,证实在显示叶状和BB症状的样品中存在大量的植原体,与qPCR结果一致。这些发现挑战了传统的理解,即植原体感染动力学导致后期更高的滴度,如WB(过度营养生长),而不是在早期阶段,如叶形(生殖生长异常)。此外,附属物中的PPT植物浆滴度明显高于番茄植物,表明宿主之间不同的敏感性。这项研究揭示了不同的宿主反应,对PPT植原体感染,提供对植物血浆滴度动态和症状发展的有价值的见解,对未来农业疾病的管理具有重要意义。
Phytoplasmas are intracellular pathogenic bacteria that infect a wide range of plant species, including agriculturally important crops and ornamental trees. However, our understanding of the relationship between symptom severity, disease progression, and phytoplasma concentration remains limited due to the inability to inoculate phytoplasmas mechanically into new plant hosts. The present study investigated phytoplasma titer dynamics and symptom development in periwinkle and tomato, both infected with the same potato purple top (PPT) phytoplasma strain using a small seedling grafting approach. Virescence, phyllody, and witches\'-broom (WB) symptoms sequentially developed in periwinkle, while in tomato plants, big bud (BB, a form of phyllody), cauliflower-like inflorescence (CLI), and WB appeared in order. Results from quantitative polymerase chain reaction (qPCR) targeting the PPT phytoplasma\'s 16S rRNA gene revealed that in both host species, phytoplasma titers differed significantly at different infection stages. Notably, the highest phytoplasma concentration in periwinkles was observed in samples displaying phyllody symptoms, whereas in tomatoes, the titer peaked at the BB stage. Western blot analysis, utilizing an antibody specific to PPT phytoplasma, confirmed substantial phytoplasma presence in samples displaying phyllody and BB symptoms, consistent with the qPCR results. These findings challenge the conventional understanding that phytoplasma infection dynamics result in a higher titer at later stages, such as WB (excessive vegetative growth), rather than in the early stage, such as phyllody (abnormal reproductive growth). Furthermore, the PPT phytoplasma titer was markedly higher in periwinkles than in tomato plants, indicating differing susceptibilities between the hosts. This study reveals distinct host responses to PPT phytoplasma infection, providing valuable insights into phytoplasma titer dynamics and symptom development, with implications for the future management of agricultural disease.