Lamovšek Janja, Stare Barbara Gerič, Pleško Irena Mavrič, Širca Saša, Urek Gregor
Agricultural Institute of Slovenia, Plant Protection Department, Hacquetova ulica 17, SI-1000 Ljubljana, Slovenia.
Phytopathology. 2017 Jun;107(6):681-691. doi: 10.1094/PHYTO-07-16-0269-R. Epub 2017 Apr 3.
The increased incidence of the crown gall disease caused by Agrobacterium tumefaciens has long been associated with activities of root-knot nematodes (Meloidogyne spp.). Pot experiments on tomato were designed to assess plant vitality, nematode reproduction, and crown gall incidence in combined infection with Agrobacterium and Meloidogyne spp. on tomato roots. Results suggest that tomato plants infected with pathogenic A. tumefaciens 2 days before the nematodes show enhanced plant defense against M. ethiopica resulting in lower egg and gall counts on roots 45 and 90 days postinoculation (dpi); no significantly enhanced defense was observed when the plant was inoculated with bacteria and nematodes at the same time. Split-root experiments also showed that the observed interaction was systemic. Reverse-transcription quantitative polymerase chain reaction analysis that targeted several genes under plant hormonal control suggests that the suppression was mediated via systemic acquired resistance by the pathogenesis-related protein 1 and that M. ethiopica did not enhance the defense reaction of tomato against Agrobacterium spp. Nematodes completely inhibited tumor growth in a 45-day experiment if inoculated onto the roots before the pathogenic bacteria. We conclude that the observed antagonism in the tested pathosystem was the result of initially strong plant defense that was later suppressed by the invading pathogen and pest.
由根癌土壤杆菌引起的冠瘿病发病率增加，长期以来一直与根结线虫（南方根结线虫属）的活动有关。针对番茄开展了盆栽试验，以评估番茄根系在同时感染土壤杆菌和南方根结线虫属时的植株活力、线虫繁殖情况以及冠瘿发病率。结果表明，在接种线虫前两天感染致病性根癌土壤杆菌的番茄植株，对埃塞俄比亚根结线虫的防御能力增强，导致接种后45天和90天时根部的卵数和瘿瘤数减少；当植株同时接种细菌和线虫时，未观察到显著增强的防御作用。分根试验还表明，观察到的这种相互作用是系统性的。针对植物激素调控下的几个基因进行的逆转录定量聚合酶链反应分析表明，这种抑制作用是由病程相关蛋白1通过系统获得性抗性介导的，并且埃塞俄比亚根结线虫并未增强番茄对土壤杆菌属的防御反应。如果在致病细菌之前接种到根部，线虫在一项为期45天的试验中完全抑制了肿瘤生长。我们得出结论，在所测试的病害系统中观察到的拮抗作用是最初强烈的植物防御的结果，这种防御后来被入侵的病原体和害虫所抑制。
