DataSheet_1_Cell wall response of field grown Populus to Septoria infection.docx

Due to its ability to spread quickly and result in tree mortality, Sphaerulina musiva (Septoria) is one of the most severe diseases impacting Populus. Previous studies have identified that Septoria infection induces differential expression of phenylpropanoid biosynthesis genes. However, more extensive characterization of changes to lignin in response to Septoria infection is lacking. To study the changes of lignin due to Septoria infection, four field grown, naturally variant Populus trichocarpa exhibiting visible signs of Septoria infection were sampled at health, infected, and reaction zone regions for cell wall characterization. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and acid hydrolysis were applied to identify changes to the cell wall, and especially lignin. FTIR and subsequent principal component analysis revealed that infected and reaction zone regions were similar and could be distinguished from the non-infected (healthy) region. NMR results indicated the general trend that infected region had a higher syringyl:guaiacyl ratio and lower p-hydroxybenzoate content than the healthy regions from the same genotype. Finally, Klason lignin content in the infected and/or reaction zone regions was shown to be higher than healthy region, which is consistent with previous observations of periderm development and metabolite profiling. These results provide insights on the response of Populus wood characteristics to Septoria infection, especially between healthy and infected region within the same genotype.

鉴于其快速传播和导致树木死亡的特性，Sphaerulina musiva（Septoria）是影响Populus最为严重的病害之一。既往研究已证实，Septoria感染可诱导苯丙素生物合成基因的差异表达。然而，关于Septoria感染对木质素变化的广泛表征尚显不足。为探究Septoria感染导致的木质素变化，本研究选取了四个在田间自然生长且表现出Septoria感染明显症状的Populus trichocarpa样本，分别在健康、感染和反应区区域进行取样，以进行细胞壁特征分析。采用傅里叶变换红外光谱（FTIR）、核磁共振（NMR）和酸水解技术，识别细胞壁的变化，尤其是木质素的变化。FTIR及其后续主成分分析揭示了感染区和反应区与未感染（健康）区相似，并可被区分。NMR结果表明，与同基因型的健康区域相比，感染区域的愈创木基：间苯三酚基比更高，而p-羟基苯甲酸含量更低。最终，感染区和/或反应区的Klason木质素含量被证实高于健康区，这与先前关于树皮发育和代谢物谱观察到的结果相一致。这些结果为Populus木材特性对Septoria感染的反应提供了见解，特别是同基因型内健康区和感染区之间的差异。