Brassica napus is highly susceptible towards Verticillium longisporum (Vl43) with no effective genetic resistance. It is believed that the fungus reprogrammes plant physiological processes by up‐regulation of so‐called susceptibility factors to establish a compatible interaction. By transcriptome analysis, we identified genes, which were activated/up‐regulated in rapeseed after Vl43 infection. To test whether one of these genes is functionally involved in the infection process and loss of function would lead to decreased susceptibility, we firstly challenged KO lines of corresponding Arabidopsis orthologs with Vl43 and compared them with wild‐type plants. Here, we report that the KO of AtCRT1a results in drastically reduced susceptibility of plants to Vl43. To prove crt1a mutation also decreases susceptibility in B. napus, we identified 10 mutations in a TILLING population. Three T3 mutants displayed increased resistance as compared to the wild type. To validate the results, we generated CRISPR/Cas‐induced BnCRT1a mutants, challenged T2 plants with Vl43 and observed an overall reduced susceptibility in 3 out of 4 independent lines. Genotyping by allele‐specific sequencing suggests a major effect of mutations in the CRT1a A‐genome copy, while the C‐genome copy appears to have no significant impact on plant susceptibility when challenged with Vl43. As revealed by transcript analysis, the loss of function of CRT1a results in activation of the ethylene signalling pathway, which may contribute to reduced susceptibility. Furthermore, this study demonstrates a novel strategy with great potential to improve plant disease resistance.

中文翻译：

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CRT1a（钙网蛋白）功能的丧失降低了拟南芥和油菜（甘蓝型油菜）中植物对黄萎病菌的敏感性。

甘蓝型油菜对黄萎病菌（Vl43）非常敏感，没有有效的遗传抗性。可以认为，真菌通过上调所谓的敏感性因子来重新建立植物的生理过程，从而建立相容的相互作用。通过转录组分析，我们鉴定了在Vl43感染后油菜中被激活/上调的基因。为了测试这些基因之一是否在功能上参与了感染过程，而功能丧失会导致易感性降低，我们首先用Vl43攻击相应拟南芥直系同源基因的KO系，并将其与野生型植物进行比较。在这里，我们报告AtCRT1a的KO结果导致植物对Vl43的敏感性大大降低。为了证明crt1a突变还降低了甘蓝型油菜的易感性，我们在TILLING人群中鉴定出10个突变。与野生型相比，三个T3突变体显示出增加的抗性。为了验证结果，我们生成了CRISPR / Cas诱导的BnCRT1a突变体，用Vl43攻击T2植物，并在4个独立系中的3个中观察到总体敏感性降低。等位基因特异性测序的基因分型表明，CRT1a A基因组拷贝中突变的主要作用，而C基因组拷贝在受到Vl43攻击时似乎对植物的敏感性没有显着影响。。如转录本分析所揭示，CRT1a功能的丧失导致乙烯信号传导途径的激活，这可能有助于降低敏感性。此外，这项研究表明了一种具有提高植物抗病性的巨大潜力的新策略。