The transmission of Potato Virus S by the cutting knife and retention time of infectious PVS on common surfaces

The transmission of PVS by the cutting knife in potato cvs Norland, Kennebec and Russet Burbank was studied in the field and greenhouse. Field studies showed transmission to Norland via tuber infection was significantly less than for Kennebec and Russet Burbank (P = 0.01). However, significant cultivar differences were not found in the greenhouse (P = 0.05). Contamination of the cutting knife by cutting through sprouts resulted in significantly greater numbers of plants infected for cv Kennebec than when sprout contact was avoided (P = 0.05). Although the same trends were observed for cv Norland and Russet Burbank the differences were not significant (P = 0.05). Infectious PVS particles were readily recovered from materials commonly contacted during potato cultivation, storage and processing. Retention time of infectious PVS was usually greater when materials were held at 4°C and 100% relative humidity than at ambient greenhouse conditions. Retention times ranged from 0 hr (PVS not recovered) to 180 hr on unpainted wood. Results demonstrated the need for strict indexing and sanitation procedures during the production of PVS-free potato seed.     

马铃薯X病毒的RT-PCR和IC-RT-PCR检测

马铃薯X病毒(Potato virus X,PVX)是侵染马铃薯重要病毒之一,通常引起花叶症状,在田间常与其他病毒混合感染导致马铃薯的毁灭性减产。PVX尚无有效的药剂可以防治,加强对PVX的快速检测是一个亟待解决的课题。本研究应用反转录聚合酶链式反应(RT-PCR)和免疫捕捉反转录聚合酶链式反应(IC-RT-PCR)技术检测马铃薯X病毒。结果表明:IC-RT-PCR方法可检测出稀释至1.0×10-3的粗汁液中的病毒;RT-PCR方法可从稀释至1.0×10-4的总RNA中扩增出特异的目的条带。这两种方法均具有较高的检测灵敏度,均可用于马铃薯X病毒的检测。     

Incidence of Cymbidium mosaic virus and Odontoglossum ringspot virus affecting Oncidium orchids in Hainan Island,China

Oncidium is the most popular cut flower for the orchid industry in Hainan Island and several viruses have been reported to negatively impact their growth and yield. A survey of Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV) in Oncidium orchids cultivated in Hainan Island was conducted during 2009–2012 with indirect enzyme-linked immunosorbent assay (ELISA). A total of 171,585 samples from adult plant, tissue-culture flask, seedling, and medium seedling were tested for CymMV and ORSV. Of the 24,125 adult plant samples from eighteen commercial orchid farms, 77.58% were infected with CymMV, 16.04% with ORSV, and 10.19% with both CymMV and ORSV. Of the 67,080 samples cultivated in tissue-culture flasks from eight tissue culture laboratories, 41.18% were infected with CymMV, 6.11% with ORSV, and 4.46% with both CymMV and ORSV. Of the 54,450 seedling samples from eight seedling nurseries, 53.20% were infected with CymMV, 9.00% with ORSV, and 5.23% with both CymMV and ORSV. And of the other 25,930 medium seedling samples from twelve medium seedling nurseries, 44.96% were infected with CymMV, 7.90% with ORSV, and 5.15% with both CymMV and ORSV. Plant material must be tested for the presence of viruses before being used for mass production by tissue culture, and sanitation during propagation of orchid plants and harvesting of flowers is essential in order to prevent the virus from spreading. These findings emphasize the need to implement a virus-free certification programme that would greatly enhance the management of these two prevalent viruses in the Hainan orchid industry.