Rossi Marika, Galetto Luciana, Bodino Nicola, Beltramo Jessica, Gamalero Silvia, Pegoraro Mattia, Bosco Domenico, Marzachì Cristina
Istituto per la Protezione Sostenibile delle Piante, Consiglio Nazionale delle Ricerche, IPSP-CNR, Strada delle Cacce 73, 10135 Torino, Italy.
Dipartimento di Scienze Agrarie, Forestali ed Alimentari DISAFA, Università degli Studi di Torino, Largo Paolo Braccini 2, 10095 Grugliasco, Italy.
Insects. 2023 Jun 23;14(7):575. doi: 10.3390/insects14070575.
Phytoplasmas are plant pathogenic wall-less bacteria transmitted in a persistent propagative manner by hemipteran insects, mainly belonging to the suborder Auchenorrhyncha (Fulgoromorpha and Cicadomorpha). Flavescence dorée (FD) is a quarantine disease of grapevine, causing great damage to European viticulture and associated with phytoplasmas belonging to 16SrV-C (FD-C) and -D (FD-D) subgroups. FD-C and FD-D strains share similar pathogenicity, but mixed infections are rare in nature. To investigate the competition among FDp strains, specimens of the laboratory vector (Hemiptera: Cicadellidae) were forced to acquire both phytoplasma haplotypes upon feeding on FD-C- and FD-D-infected plants or after the injection of both strains. The pathogen colonization of insect bodies and heads was monitored with multiplex qPCR, and the efficiencies of phytoplasma transmission were estimated. Single infection, irrespective of strain type, was more frequent than expected, indicating that competition among FD strains occurs. Hypotheses of competition for resources and/or host active sites or the direct antibiosis of one strain against the other are discussed, based on the genetic complexity of FDp populations and on the high genome variability of the FD-D strain. As FD management still mainly relies on insecticides against vectors, the characterization of FDp haplotypes and the description of their epidemiology also have practical implications.
植原体是一类植物致病的无细胞壁细菌，通过半翅目昆虫以持久性增殖方式传播，这些昆虫主要属于头喙亚目（蜡蝉亚目和叶蝉亚目）。葡萄黄化病（FD）是葡萄的一种检疫性病害，对欧洲葡萄栽培造成了巨大损失，与属于16SrV-C（FD-C）和-D（FD-D）亚组的植原体有关。FD-C和FD-D菌株具有相似的致病性，但在自然条件下混合感染很少见。为了研究FDp菌株之间的竞争，实验室载体（半翅目：叶蝉科）的标本在取食FD-C和FD-D感染的植物后或注射这两种菌株后被迫获得两种植原体单倍型。用多重定量PCR监测昆虫身体和头部的病原体定殖情况，并估计植原体的传播效率。无论菌株类型如何，单感染都比预期更频繁，这表明FD菌株之间存在竞争。基于FDp群体的遗传复杂性和FD-D菌株的高基因组变异性，讨论了资源和/或宿主活性位点竞争或一种菌株对另一种菌株的直接抗菌作用的假设。由于FD的管理仍然主要依赖于针对载体的杀虫剂，FDp单倍型的特征及其流行病学描述也具有实际意义。
