Verticillium longisporum infects oilseed rape (Brassica napus) and Arabidopsis thaliana. To investigate the early response of oilseed rape to the fungal infection, we determined transcriptomic changes in oilseed rape roots at 6 days post‐inoculation (dpi) by RNA‐Seq analysis, in which non‐infected roots served as a control. Strikingly, a subset of genes involved in abscisic acid (ABA) biosynthesis was found to be down‐regulated and the ABA level was accordingly attenuated in 6 dpi oilseed rape as compared with the control. Gene expression analysis revealed that this was mainly attributed to the suppression of BnNCED3‐mediated ABA biosynthesis, involving, for example, BnWRKY57. However, this down‐regulation of ABA biosynthesis could not be observed in infected Arabidopsis roots. Arabidopsis ABA‐ defective mutants nced3 and aao3 displayed pronounced tolerance to the fungal infection with delayed and impeded symptom development, even though fungal colonization was not affected in both mutants. These data suggest that ABA appears to be required for full susceptibility of Arabidopsis to the fungal infection. Furthermore, we found that in both 6 dpi oilseed rape and the Arabidopsis nced3 mutant, the salicylic acid (SA) signalling pathway was induced while the jasmonic acid (JA)/ethylene (ET) signalling pathway was concomitantly mitigated. Following these data, we conclude that in oilseed rape the V. longisporum infection triggers a host‐specific suppression of the NCED3‐mediated ABA biosynthesis, consequently increasing plant tolerance to the fungal infection. We believe that this might be part of the virulence strategy of V. longisporum to initiate/establish a long‐lasting compatible interaction with oilseed rape (coexistence), which appears to be different from the infection process in Arabidopsis.

中文翻译：

---

油菜（Brassica napus）中黄萎病菌（Verticillium longisporum）感染初期的脱落酸生物合成抑制。

黄萎病菌感染油菜（甘蓝型油菜）和拟南芥。为了调查油菜​​对真菌感染的早期反应，我们通过RNA-Seq分析确定了接种后（dpi）第6天油菜油菜根的转录组变化，其中未感染的根作为对照。令人惊讶的是，发现与脱落酸相比，脱落酸（ABA）生物合成相关基因的一个子集被下调，因此ABA水平在6 dpi油菜中得到减弱。基因表达分析表明，这主要归因于BnNCED3介导的ABA生物合成的抑制，例如涉及BnWRKY57。但是，在受感染的拟南芥根中未观察到这种ABA生物合成的下调。拟南芥ABA缺陷型突变体nced3和aao3对真菌感染表现出明显的耐受性，延迟和阻碍了症状的发展，即使真菌定植在这两个突变体中均不受影响。这些数据表明ABA似乎是拟南芥对真菌感染的完全易感性所必需的。此外，我们发现6 dpi油菜和拟南芥nced3突变，水杨酸（SA）信号传导途径被诱导，而茉莉酸（JA）/乙烯（ET）信号传导途径被同时缓解。根据这些数据，我们得出结论，在油菜中，长孢菌感染会触发宿主特异性抑制NCED3介导的ABA生物合成，从而提高植物对真菌感染的耐受性。我们认为，这可能是V.longisporum的毒力策略的一部分，以启动/建立与油菜的持久相容性相互作用（共存），这似乎与拟南芥的感染过程不同。