Ling Kai-Shu
U.S. Department of Agriculture-Agricultural Research Service, U.S. Vegetable Laboratory, Charleston, SC 29414.
Plant Dis. 2008 Dec;92(12):1701-1705. doi: 10.1094/PDIS-92-12-1701.
In just a few years, Pepino mosaic virus (PepMV) has become a major threat to greenhouse tomato production around the world. Although tomato seed is suspected to spread the disease, its importance as an initial virus inoculum for PepMV has not been established. To determine the potential for seed transmission, a tomato seed lot highly contaminated with PepMV was used for large-scale seedling grow-out tests. None of 10,000 grow-out seedlings was infected as determined by symptom expression, enzyme-linked immunosorbent assay (ELISA), or infectivity assay on Nicotiana benthamiana. Even though PepMV was not seed transmitted on tomato, the virus was effectively transmitted to tomato and N. benthamiana seedlings through mechanical transmission with seed extract. To examine the exact location where PepMV particles accumulated on the tomato seed, seed coats and embryos were carefully isolated and tested separately by ELISA, real-time RT-PCR, and bioassay on N. benthamiana. PepMV was detected in the seed coat fraction in both immature and mature tomato seeds, but not in the embryo. However, in N. benthamiana, the virus was neither seedborne nor seed-transmitted. Because PepMV is seedborne in tomato, efficient mechanical transmission of PepMV from the virus-contaminated tomato seed to seedlings could initiate a disease epidemic in a new tomato growing area. Thus, it is important to plant certified tomato seed that has been tested free of PepMV.
在短短几年内， Pepino花叶病毒（PepMV）已成为全球温室番茄生产的主要威胁。尽管怀疑番茄种子会传播这种疾病，但它作为PepMV初始病毒接种体的重要性尚未确定。为了确定种子传播的可能性，使用了一批高度感染PepMV的番茄种子进行大规模的幼苗生长试验。通过症状表现、酶联免疫吸附测定（ELISA）或对本氏烟草的感染性测定，确定10000株生长的幼苗均未感染。尽管PepMV不会通过种子传播给番茄，但该病毒通过种子提取物的机械传播有效地传播到了番茄和本氏烟草幼苗上。为了检查PepMV颗粒在番茄种子上积累的确切位置，仔细分离了种皮和胚，并分别通过ELISA、实时RT-PCR和对本氏烟草的生物测定进行检测。在未成熟和成熟番茄种子的种皮部分均检测到PepMV，但在胚中未检测到。然而，在本氏烟草中，该病毒既不是种子携带的，也不是通过种子传播的。由于PepMV在番茄中是种子携带的，PepMV从受病毒污染的番茄种子到幼苗的有效机械传播可能会在新的番茄种植区引发疾病流行。因此，种植经过检测不含PepMV的认证番茄种子非常重要。
