BACKGROUND Witches' broom disease (WBD) of cacao (Theobroma cacao L.), caused by Moniliophthora perniciosa, is the most important limiting factor for the cacao production in Brazil. Hence, the development of cacao genotypes with durable resistance is the key challenge for control the disease. Proteomic methods are often used to study the interactions between hosts and pathogens, therefore helping classical plant breeding projects on the development of resistant genotypes. The present study compared the proteomic alterations between two cacao genotypes standard for WBD resistance and susceptibility, in response to M. perniciosa infection at 72 h and 45 days post-inoculation; respectively the very early stages of the biotrophic and necrotrophic stages of the cacao x M. perniciosa interaction. RESULTS A total of 554 proteins were identified, being 246 in the susceptible Catongo and 308 in the resistant TSH1188 genotypes. The identified proteins were involved mainly in metabolism, energy, defense and oxidative stress. The resistant genotype showed more expressed proteins with more variability associated with stress and defense, while the susceptible genotype exhibited more repressed proteins. Among these proteins, stand out pathogenesis related proteins (PRs), oxidative stress regulation related proteins, and trypsin inhibitors. Interaction networks were predicted, and a complex protein-protein interaction was observed. Some proteins showed a high number of interactions, suggesting that those proteins may function as cross-talkers between these biological functions. CONCLUSIONS We present the first study reporting the proteomic alterations of resistant and susceptible genotypes in the T. cacao x M. perniciosa pathosystem. The important altered proteins identified in the present study are related to key biologic functions in resistance, such as oxidative stress, especially in the resistant genotype TSH1188, that showed a strong mechanism of detoxification. Also, the positive regulation of defense and stress proteins were more evident in this genotype. Proteins with significant roles against fungal plant pathogens, such as chitinases, trypsin inhibitors and PR 5 were also identified, and they may be good resistance markers. Finally, important biological functions, such as stress and defense, photosynthesis, oxidative stress and carbohydrate metabolism were differentially impacted with M. perniciosa infection in each genotype.

中文翻译：

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病原菌Moniliophthora perniciosa促进了可可基因型的差异蛋白质组学调节，而对女巫的扫帚病具有相反的抵抗力。

背景技术由念珠菌（Moniliophthora perniciosa）引起的可可（Theobroma cacao L.）女巫的扫帚病（WBD）是巴西可可生产的最重要限制因素。因此，具有持久抗性的可可基因型的发展是控制该疾病的关键挑战。蛋白质组学方法通常用于研究宿主与病原体之间的相互作用，因此有助于经典植物育种项目发展抗性基因型。本研究比较了两种可可基因型在WBD耐药性和易感性标准之间的蛋白质组学变化，该基因型是在接种后72 h和45天对多年生支原体感染的反应。可可x多年生黑麦草互作的生养阶段和坏死阶段分别处于非常早期。结果共鉴定出554种蛋白质，在易感的Catongo中为246，而在抗性TSH1188基因型中为308。鉴定出的蛋白质主要参与新陈代谢，能量，防御和氧化应激。抗性基因型显示出更多表达的蛋白，与应激和防御相关的变异性更大，而易感基因型显示出更多受抑制的蛋白。在这些蛋白质中，与发病机理相关的蛋白质（PRs），与氧化应激调节相关的蛋白质和胰蛋白酶抑制剂非常引人注目。可以预测相互作用网络，并观察到复杂的蛋白质-蛋白质相互作用。一些蛋白质显示出大量的相互作用，表明这些蛋白质可能在这些生物学功能之间起串扰作用。结论我们提出了第一项研究，报告了T. cacao x M. perniciosa病理系统中抗药性和易感基因型的蛋白质组学变化。本研究中鉴定出的重要变异蛋白与抗性的关键生物学功能有关，例如氧化应激，尤其是在具有强力排毒机制的抗性基因型TSH1188中。同样，防御和应激蛋白的正调控在该基因型中更为明显。还鉴定了对真菌植物病原体具有重要作用的蛋白质，例如几丁质酶，胰蛋白酶抑制剂和PR 5，它们可能是良好的抗性标记。最后，重要的生物学功能，如胁迫和防御，光合作用，氧化应激和碳水化合物代谢受M的影响不同。