Department of Botany, North Carolina State University, Raleigh, NC 27695, USA.
Mol Plant Pathol. 2002 May 1;3(3):145-52. doi: 10.1046/j.1364-3703.2002.00106.x.
Summary A root knot nematode resistance gene in Nicotiana tabacum, Rk, providing resistance to the nematode parasite Meloidogyne incognita is tightly linked to, or is a pleiotropic gene with a veinal necrosis systemic hypersensitive response to infection by Potato virus Y (PVY) M(s)N(r). The single PVY M(s)N(r) open reading frame was sequenced and found to have 89% protein identity to PVY N. Individual PVY M(s)N(r) polypeptides were deduced and the corresponding cDNA were cloned into a Potato virus X (PVX) based expression vector and used as templates for in vitro transcriptions. Infected plant sap, from N. benthamiana inoculated with infectious RNA, was used to inoculate both root knot nematode (RKN) resistant and susceptible tobacco lines. Lines were then evaluated for the induction of the hypersensitive response. The PVY M(s)N(r) NIb-replicase protein was found to induce a hypersensitive response 10 days post inoculation in nematode resistant tobacco. None of the other PVX/PVY M(s)N(r) constructs induced a hypersensitive response. The NIb-replicase of PVY N, which shares 93% identity to PVY M(s)N(r), did not induce a hypersensitive response when expressed from the PVX vector. This confirmed that the PVY M(s)N(r) NIb-replicase is the elicitor of PVY M(s)N(r) veinal necrosis on RKN plants and thus the first report of a Potyvirus replicase functioning as an avirulence factor.
在烟草中，与马铃薯 Y 病毒（PVY）M(s)N(r)介体系统坏死的维管束过敏反应紧密连锁或为其多效基因的根结线虫抗性基因 Rk 可抵抗根结线虫寄生。对马铃薯 Y 病毒（PVY）M(s)N(r)的单一开放阅读框进行了测序，发现其与 PVY N 的蛋白序列有 89%的同源性。推断出个别 PVY M(s)N(r)多肽，并将相应的 cDNA 克隆到基于马铃薯 X 病毒（PVX）的表达载体中，用作体外转录的模板。从用传染性 RNA 接种的 N. benthamiana 感染植物汁液中提取的汁液，用于接种抗根结线虫和易感烟草品系。然后评估这些品系对过敏反应的诱导情况。发现 PVY M(s)N(r)NIb-复制酶蛋白在接种后 10 天可在抗线虫烟草中诱导过敏反应。其他任何 PVX/PVY M(s)N(r)构建体均未诱导过敏反应。与 PVY M(s)N(r)共享 93%同一性的 PVY N 的 NIb-复制酶，当从 PVX 载体表达时，不会诱导过敏反应。这证实了 PVY M(s)N(r)NIb-复制酶是在 RKN 植物上引起 PVY M(s)N(r)叶脉坏死的激发子，这也是首次报道 Potyvirus 复制酶作为无毒因子发挥作用。
