Zhang Qi, Chen Xi, You Haixia, Chen Bing, Jia Liyu, Li Sizhe, Zhang Xinyu, Ma Ji, Wu Xinyi, Wang Kaixiang, Liu Huanshan, Jiang Haibin, Xiao Junhua, Shu Haidong, Zhang Zhichao, Qiu Min, Xia Yeqiang, Chen Han, Wang Yan, Ye Wenwu, Dong Suomeng, Ma Zhenchuan, Wang Yuanchao
Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, China.
Key Laboratory of Soybean Disease and Pest Control (Ministry of Agriculture and Rural Affairs), Nanjing Agricultural University, Nanjing, 210095, China.
Nat Commun. 2025 Apr 17;16(1):3638. doi: 10.1038/s41467-025-58770-x.
In diverse Phytophthora-plant pathosystems, Phytophthora secretes XLP1 (PsXEG1-Like Protein), a non-enzymatic paralog that functions as a decoy to protect XEG1 (Xyloglucan-specific Endoglucanase) from host inhibitors. Here, we show that the genus-specific selection pressures on the XEG1/XLP1 gene pair are crucial for host adaptation and are closely linked to Phytophthora host range. Our findings reveal that the XEG1/XLP1 gene pair originated within Phytophthora and subsequently evolved into genus-specific genes, undergoing functional divergence driven by preferential selection. Positive selection sites within the XEG1/XLP1 gene pair in Phytophthora contribute to this functional divergence and are associated with the host range variability of Phytophthora as evidenced by multivariate statistical analyses. Furthermore, mutations at key selection sites in Phytophthora sojae and Phytophthora capsici significantly impair their pathogenicity, with P. capsici exhibiting almost no colonization expansion on tobacco and pea. Notably, natural Phytophthora populations harbor mutations at the positive selection sites, indicating ongoing evolutionary pressures on the XEG1/XLP1 gene pair.
在多种疫霉属植物病原体系中，疫霉分泌XLP1（类PsXEG1蛋白），它是一种非酶旁系同源物，作为诱饵保护XEG1（木葡聚糖特异性内切葡聚糖酶）免受宿主抑制剂的影响。在此，我们表明XEG1/XLP1基因对的属特异性选择压力对宿主适应性至关重要，并且与疫霉属的宿主范围密切相关。我们的研究结果表明，XEG1/XLP1基因对起源于疫霉属内部，随后进化为属特异性基因，在优先选择的驱动下发生功能分化。疫霉属中XEG1/XLP1基因对中的正选择位点促成了这种功能分化，并与疫霉属的宿主范围变异性相关，多变量统计分析证明了这一点。此外，大豆疫霉和辣椒疫霉关键选择位点的突变显著损害了它们的致病性，辣椒疫霉在烟草和豌豆上几乎没有定殖扩展。值得注意的是，自然疫霉种群在正选择位点存在突变，表明XEG1/XLP1基因对持续受到进化压力。
