Foxe M J, Prakash J
Arch Virol. 1986;88(3-4):167-74. doi: 10.1007/BF01310872.
Resistance to Potato Virus X (PVX) in potato cultivars is conferred by the genes Nx and/or Nb. The Nx gene is activated by group 3 strains of PVX. When protoplasts from the cultivars King Edward containing the Nx gene and Pentland Crown containing neither resistance gene were inoculated with a group 3 strain of PVX resistance was expressed in the King Edward protoplasts. Replication of PVX occurred in King Edward protoplasts but only at a very low level as compared with the level observed in the susceptible Pentland Crown protoplasts. Similar results were obtained when protoplasts obtained from leaf discs mechanically inoculated with PVX were used. Virus levels were assayed by immunofluorescence and ELISA. Maintenance of resistance in protoplasts of King Edward following inoculation with PVX RNA was confirmed suggesting that resistance probably operates at the transcription stage in replication. These results clearly demonstrate single gene resistance in potato protoplasts inoculated with PVX.
马铃薯品种对马铃薯X病毒（PVX）的抗性由基因Nx和/或Nb赋予。Nx基因被PVX的3组毒株激活。当用PVX的3组毒株接种含有Nx基因的爱德华国王品种和既不含有抗性基因的彭特兰皇冠品种的原生质体时，爱德华国王品种的原生质体表现出抗性。PVX在爱德华国王品种的原生质体中发生复制，但与在敏感的彭特兰皇冠品种原生质体中观察到的水平相比，仅处于非常低的水平。当使用从机械接种PVX的叶盘获得的原生质体时，也得到了类似的结果。通过免疫荧光和酶联免疫吸附测定法检测病毒水平。接种PVX RNA后，爱德华国王品种原生质体中抗性的维持得到证实，这表明抗性可能在复制的转录阶段起作用。这些结果清楚地证明了接种PVX的马铃薯原生质体中的单基因抗性。
