Phytopathology. 2006 Mar;96(3):255-63. doi: 10.1094/PHYTO-96-0255.
ABSTRACT The effects of salicylic acid (SA) and 1-aminocyclopropane-1-carboxylic acid (ACC) on the systemic development of symptoms induced by a severe isolate of Potato virus Y group N:O (PVY(N:O)) in tobacco were investigated. Upon inoculation, the systemic development of symptoms in tobacco plants could be divided into three stages: virus incubation stage, rapid symptom-progress stage, and partial recovery and symptom-shifting stage. Treatment of seedlings with SA delayed the virus-induced necrosis in stems by 1 to 2 days. SA, not ACC, also significantly suppressed the symptom severity in stems. However, neither SA nor ACC treatment affected the partial recovery phenotype exhibited in the latterly emerged upper parts of the plants. Further analysis indicated that the accumulation of PVY was retarded by SA at the early stage of infection, and the effects were more profound in stems than leaves. Peroxidase (POX) activity and pathogenesis-related (PR) genes PR-1a and PR-1b were enhanced by PVY infection. SA not only increased POX activity in stems and PR genes in stems and leaves of mock-inoculated plants, but also elevated the activity of POX in both leaves and stems and the expression of PR-1a in leaves of PVY-infected plants. Together, the results suggest that systemic acquired resistance plays a key role in suppressing PVY(N:O)-induced symptom development through SA-mediated and ethylene-independent pathways. The symptom suppression was correlated with reduced replication/ accumulation of virus at the early stage of infection. The results also suggest that neither SA nor ethylene plays a role in the recovery phenotype.
摘要 本研究调查了水杨酸（SA）和 1-氨基环丙烷-1-羧酸（ACC）对烟草上强毒分离物马铃薯 Y 病毒组 N:O（PVY（N:O））诱导的系统症状发展的影响。接种后，烟草植株系统症状的发展可分为三个阶段：病毒潜伏期、快速症状进展期和部分恢复及症状转移期。幼苗用 SA 处理可使茎部病毒诱导的坏死延迟 1-2 天。SA 而非 ACC 也显著抑制了茎部的症状严重程度。然而，SA 和 ACC 处理均不影响植株上部后期出现的部分恢复表型。进一步分析表明，SA 在感染早期可延缓 PVY 的积累，且在茎部的效果比叶片更显著。过氧化物酶（POX）活性和病程相关（PR）基因 PR-1a 和 PR-1b 被 PVY 感染所诱导。SA 不仅增加了模拟接种植株茎部的 POX 活性和茎部及叶片中 PR 基因的表达，还提高了 PVY 感染植株叶片和茎部的 POX 活性及 PR-1a 的表达。综上，结果表明，通过 SA 介导的和乙烯非依赖途径，系统获得性抗性在抑制 PVY（N:O）诱导的症状发展中起关键作用。症状的抑制与感染早期病毒复制/积累减少有关。结果还表明，SA 和乙烯均不参与恢复表型。
