Nucleo de Biotecnologia Universidade Federal do Espírito Santo, Vitória, Espírito Santo 29040-090, Brazil.
Universidad El Bosque, Vicerrectoría de Investigaciones, Bogota, Colombia.
Plant Dis. 2020 Nov;104(11):2754-2763. doi: 10.1094/PDIS-12-19-2622-FE. Epub 2020 Aug 19.
Among the most serious problems in papaya production are the viruses associated with papaya ringspot and papaya sticky disease (PSD). PSD concerns producers worldwide because its symptoms are extremely aggressive and appear only after flowering. As no resistant cultivar is available, several disease management strategies have been used in affected countries, such as the use of healthy seeds, exclusion of the pathogen, and roguing. In the 1990s, a dsRNA virus, papaya meleira virus (PMeV), was identified in Brazil as the causal agent of PSD. However, in 2016 a second virus, papaya meleira virus 2 (PMeV2), with an ssRNA genome, was also identified in PSD plants. Only PMeV is detected in asymptomatic plants, whereas all symptomatic plants contain both viral RNAs separately packaged in particles formed by the PMeV capsid protein. PSD also affects papaya plants in Mexico, Ecuador, and Australia. PMeV2-like viruses have been identified in the affected plants, but the partner virus(es) in these countries are still unknown. In Brazil, PMeV and PMeV2 reside in laticifers that promote spontaneous latex exudation, resulting in the affected papaya fruit's sticky appearance. Genes modulated in plants affected by PSD include those involved in reactive oxygen species and salicylic acid signaling, proteasomal degradation, and photosynthesis, which are key plant defenses against PMeV complex infection. However, the complete activation of the defense response is impaired by the expression of negative effectors modulated by the virus. This review presents a summary of the current knowledge of the -PMeV complex interaction and management strategies.
番木瓜生产中最严重的问题之一是与番木瓜环斑病和番木瓜黏滞病（PSD）相关的病毒。PSD 引起了全世界种植者的关注，因为其症状极具攻击性，仅在开花后出现。由于没有抗性品种，受影响的国家采用了几种疾病管理策略，例如使用健康种子、排除病原体和剔除病株。20 世纪 90 年代，巴西鉴定出一种 dsRNA 病毒，即番木瓜梅利拉病毒（PMeV），为 PSD 的致病因子。然而，2016 年在 PSD 植株中还鉴定出第二种病毒，即具有 ssRNA 基因组的番木瓜梅利拉病毒 2（PMeV2）。仅在无症状植株中检测到 PMeV，而所有有症状的植株中均分别含有单独包装在由 PMeV 衣壳蛋白形成的颗粒中的两种病毒 RNA。PSD 还影响墨西哥、厄瓜多尔和澳大利亚的番木瓜植株。在受影响的植株中鉴定出了与 PMeV2 相似的病毒，但这些国家的伴生病毒（s）仍未知。在巴西，PMeV 和 PMeV2 存在于乳管中，促进自发乳胶渗出，导致受影响的番木瓜果实出现粘性外观。PSD 影响的植株中调节的基因包括参与活性氧和水杨酸信号转导、蛋白酶体降解和光合作用的基因，这些是植物对 PMeV 复合感染的关键防御机制。然而，病毒调节的负效因子的表达会损害防御反应的完全激活。本综述总结了目前关于-PMeV 复合相互作用和管理策略的知识。
