Zamani-Noor Nazanin, Krohne Imke, Koopmann Birger
Julius Kühn-Institute (JKI)-Federal Research Centre for Cultivated Plants, Institute for Plant Protection in Field Crops and Grassland, Messeweg 11-12, 38104 Braunschweig, Germany.
Department of Crop Sciences, Division of Plant Pathology and Crop Protection, Georg August University, Grisebachstr. 6, 37077 Göttingen, Germany.
Pathogens. 2021 Feb 2;10(2):151. doi: 10.3390/pathogens10020151.
Clubroot resistance of oilseed rape (OSR) cultivars frequently relies on a major resistance gene originating from cv. Mendel. The efficacy of this resistance was studied in greenhouse experiments using two isolates, which were either virulent (P1(+)) or avirulent (P1) on Mendel. Seeds of clubroot-susceptible cultivar Visby and clubroot-resistant cultivar Mendel were sown in soil mixtures inoculated with different concentrations of resting spores (10, 10, 10, and 10 resting spores/g soil). Clubroot severity, plant height, shoot and root weight as well as resting spore propagation were assessed for each isolate and cultivar separately at four dates after sowing. The OSR cultivars behaved significantly different in the measured parameters. The threshold of inoculum density to cause disease depended strongly on the virulence of the pathogen and susceptibility of the host plant. In Visby grown in soil infested with P1, clubroot symptoms and increases in root weight and the number of propagated resting spores occurred at inoculum levels of 10 resting spores and higher, whereas Mendel was not affected in soils under the three lowest inoculum densities. In contrast, the P1(+) isolate led to earlier and more severe symptoms, heavier galls, and a significantly higher number of new resting spores in both cultivars.
油菜（OSR）品种的根肿病抗性通常依赖于一个源自品种Mendel的主要抗性基因。在温室试验中，使用了两种分离物来研究这种抗性的效果，这两种分离物对Mendel要么是致病的（P1(+)），要么是无毒的（P1）。将根肿病易感品种维斯比（Visby）和根肿病抗性品种Mendel的种子播种在接种了不同浓度休眠孢子（10⁴、10⁵、10⁶和10⁷个休眠孢子/克土壤）的土壤混合物中。在播种后的四个日期分别对每个分离物和品种评估根肿病严重程度、株高、地上部和根部重量以及休眠孢子繁殖情况。OSR品种在测量参数上表现出显著差异。引发病害的接种体密度阈值很大程度上取决于病原体的毒力和寄主植物的易感性。在接种P1的土壤中生长的维斯比，当接种体水平达到10⁴个休眠孢子及更高时，出现了根肿病症状以及根重增加和繁殖的休眠孢子数量增多的情况，而在三种最低接种体密度的土壤中，Mendel没有受到影响。相比之下，P1(+)分离物在两个品种中都导致了更早、更严重的症状、更重的瘤以及显著更多的新休眠孢子。
