Table 1_Transcriptomic analysis reveals pathogenicity mechanisms of Phytophthora capsici in black pepper.docx

The devastating disease “quick wilt” or “foot rot” is caused by the oomycete Phytophthora capsici Leonian and is affecting the economically significant spice crop black pepper (Piper nigrum L.). The details on the mechanism of interaction of P. capsici with its host black pepper remain poorly understood, hindering efforts to enhance disease resistance. To address this knowledge gap, we conducted an RNA-seq analysis to investigate the gene expression profile of P. capsici infecting black pepper. Comparative transcriptome analysis between axenic culture, and early and late infection stages of P. capsici revealed a substantial number of differentially expressed genes. Our findings demonstrate the induction of metabolic pathways, signaling cascades, and crucial pathogenicity-related processes during infection of black pepper by P. capsici. Specifically, we observed orchestrated expression of cell wall-degrading enzymes, effectors, and, detoxifying transporters at different infection time points, implicating their roles in pathogenicity. The expression patterns of key pathogenicity-associated genes, including effectors, were validated using reverse transcription quantitative real-time PCR. The effectiveness of agroinfiltration-mediated transient expression in black pepper for functional studies of effectors is also demonstrated in this study. Overall, this study establishes a strong foundation for further studies elucidating the pathogenic mechanisms employed by P. capsici infecting black pepper and for developing effective disease management strategies. Future investigations building upon these findings are essential for advancing our understanding of this pathosystem and for implementing targeted approaches to mitigate black pepper foot rot.

毁灭性病害‘快速萎蔫病’（quick wilt）或‘根腐病’（foot rot）由卵菌辣椒疫霉（Phytophthora capsici Leonian）引发，正严重威胁经济价值显著的香辛料作物黑胡椒（Piper nigrum L.）。目前学界对辣椒疫霉与其宿主黑胡椒的互作机制仍知之甚少，这极大阻碍了抗病性改良相关研究的推进。为填补这一认知空白，本研究开展了RNA测序（RNA-seq）分析，以探究辣椒疫霉侵染黑胡椒过程中的基因表达谱。对无菌纯培养菌株，以及辣椒疫霉侵染黑胡椒的早期、晚期阶段进行比较转录组分析后，共鉴定出大量差异表达基因。研究结果显示，在辣椒疫霉侵染黑胡椒的过程中，代谢通路、信号级联反应以及关键致病相关进程均被诱导激活。具体而言，我们观察到细胞壁降解酶、效应蛋白（effectors）与解毒转运蛋白在不同侵染时间点呈现协同表达模式，这暗示它们在致病过程中发挥着重要功能。本研究通过反转录定量实时聚合酶链反应（reverse transcription quantitative real-time PCR）验证了包括效应蛋白在内的关键致病相关基因的表达模式。此外，本研究还证实了农杆菌浸润（agroinfiltration）介导的瞬时表达系统可用于黑胡椒中效应蛋白的功能研究。综上，本研究为阐明辣椒疫霉侵染黑胡椒的致病机制，以及开发高效病害防控策略奠定了坚实基础。后续基于本研究结果开展的深入探索，对于增进我们对该病害系统（pathosystem）的认知，以及制定针对性措施以减轻黑胡椒根腐病危害均具有重要意义。