DataSheet_2_Cell wall response of field grown Populus to Septoria infection.xlsx

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.

鉴于其快速传播及导致树木死亡的能力，Sphaerulina musiva（Septoria）是影响Populus最为严重的病害之一。既往研究已证实，Septoria感染会引起酚丙烷类生物合成基因的表达差异。然而，对Septoria感染引发的木质素变化的深入研究尚显不足。为探究木质素因Septoria感染而发生的变化，本研究选取了四株在田间自然生长、具有可见Septoria感染症状的Populus trichocarpa，于健康、感染和反应区域采集样本，以进行细胞壁的表征分析。采用傅里叶变换红外光谱（FTIR）、核磁共振（NMR）和酸水解等方法，以识别细胞壁及木质素的变化。FTIR及后续主成分分析表明，感染及反应区域与未感染（健康）区域相似，并可区分开来。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：间苯二酚基比更高，而p-羟基苯甲酸含量更低。最终，感染及/或反应区域的Klason木质素含量被发现高于健康区域，这与先前的树皮发育和代谢物谱观察结果相吻合。这些研究结果为Populus木材特性对Septoria感染的响应提供了洞见，特别是同基因型内健康区域与感染区域之间的差异。