该团队发现柑橘溃疡病病原菌柑橘黄单胞菌亚种。柑橘（Xcc）通过III型效应物PthA4劫持果实成熟程序，从而激活成熟协调物CsLOB1，从而调动细胞壁糖。CsLOB1诱导大约100个基因，其中许多编码酶参与细胞壁破坏。在非结果物种本氏烟草中，CsLOB1同样促进黄单胞菌的生长，表明其活性并不严格依赖于成熟程序。转录组学和报告基因分析显示PthA4依赖性的Xcc木聚糖CUT系统激活，由宿主衍生的木糖触发，包括II型分泌木聚糖酶。然后，PthA4驱动的细胞壁重塑激活细菌木聚糖主题，建立TIII-TII效应前馈循环，促进Xcc增殖。
据介绍，植物细胞壁蕴藏着大量的碳水化合物储备，但病原体是如何释放它们的，目前尚不清楚。
附：英文原文
Title: Xanthomonas coordinates type III–type II effector synergy by activating fruit-ripening pathway
Author: Trang Thi-Thu Phan, Rodrigo Silva Araujo Streit, Gerald V. Minsavage, Joachim Kilian, Paloma de los Angeles Aguilera, Nan Wang, Nicolas Brich, Robert Morbitzer, Edda von Roepenack-Lahaye, Brice Charleux, Boris Szurek, Priscila Oliveira de Giuseppe, Concetta Licciardello, Jeffrey B. Jones, Paulo J. P. L. Teixeira, Gabriela Felix Persinoti, Mario Tyago Murakami, Chang Liu, Jan Grau, Thomas Lahaye
Issue&Volume: 2025-12-18
Abstract: Plant cell walls harbor vast carbohydrate reserves, yet how pathogens unlock them remains unclear. We show that the citrus canker pathogen Xanthomonas citri subsp. citri (Xcc) mobilizes cell wall sugars by hijacking a fruit-ripening program through the type III effector PthA4, which activates the ripening coordinator CsLOB1. CsLOB1 induces approximately 100 genes, many encoding enzymes involved in cell wall breakdown. In the nonfruiting species Nicotiana benthamiana, CsLOB1 likewise promotes Xanthomonas growth, showing that its activity is not strictly dependent on a ripening program. Transcriptomics and reporter assays revealed PthA4-dependent activation of the Xcc xylan CUT system, triggered by host-derived xylose and including a type II–secreted xylanase. Thus, PthA4-driven cell wall remodeling activates bacterial xylan use, establishing a TIII–TII effector feedforward loop that fuels Xcc proliferation.
DOI: adz9239
Source: https://www.science.org/doi/10.1126/science.adz9239