Orobanche cumana is an obligate root parasite which specifically infects roots of Helianthus annuus L., causing severe yield and economic losses in agricultural fields worldwide. For an efficient control strategy, it is necessary to understand specialized host defense mechanisms and the pathogenesis of O. cumana during underground interaction with the host. RNA-Seq was used to simultaneously assess the transcriptome of each of two contrasting sunflower cultivars with O. cumana during their post-attachment interactions. Secretome prediction was applied to identify O. cumana proteins from its transcriptome. Infection of O. cumana triggered insufficient defense responses in the susceptible cultivar as compared to the resistant one, probably due to the failure to fully recognize parasite effectors. Secretome prediction from the O. cumana transcriptome enabled robust identification of 180 proteins associated with O. cumana penetration and infection. Functional annotation of these proteins revealed that they were associated with cell wall degradation, nutrient acquisition and pathogenesis. Additionally, a candidate effector containing a PAR1 domain from O. cumana was preliminarily identified as a potential suppressor of plant defense responses. Secretome prediction shed lights on the molecular mechanisms that O. cumana deployed to manipulate host defense. Successful infection of O. cumana inhibited host defense responses and turned host roots from a sink to a source for efficient nutrient flux towards the parasite. In summary, these findings provide insight into the mechanism underlying O. cumana infection and are important in understanding parasitic-host plant interaction.

中文翻译：

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两个对比向日葵品种与根寄生杂草 Orobanche cumana 地下相互作用的转录分析

Orobanche cumana 是一种专性根部寄生虫，专门感染向日葵的根部，在全球农业领域造成严重的产量和经济损失。对于有效的控制策略，有必要了解专门的宿主防御机制和 O. cumana 在与宿主的地下相互作用期间的发病机制。RNA-Seq 用于同时评估两个对比向日葵品种与 O. cumana 在它们附着后相互作用期间的转录组。分泌组预测用于从其转录组中鉴定 O. cumana 蛋白质。与抗性品种相比，O. cumana 的感染在易感品种中引发了不足的防御反应，这可能是由于未能完全识别寄生虫效应物。来自 O 的分泌组预测。cumana 转录组能够可靠地鉴定与 O. cumana 渗透和感染相关的 180 种蛋白质。这些蛋白质的功能注释表明它们与细胞壁降解、营养获取和发病机制有关。此外，包含来自 O. cumana 的 PAR1 结构域的候选效应子被初步确定为植物防御反应的潜在抑制因子。分泌组预测揭示了 O. cumana 用于操纵宿主防御的分子机制。O. cumana 的成功感染抑制了宿主防御反应，并将宿主根从一个汇变成了一个有效的营养源流向寄生虫。总之，这些发现提供了对 O. cumana 感染的潜在机制的深入了解，并且对于了解寄生宿主植物的相互作用很重要。