Key Laboratory of National Forestry and Grassland Administration on Biodiversity Conservation in Karst Mountainous Areas of Southwestern China, Key Laboratory of Plant Physiology and Development Regulation, School of Life Science, Guizhou Normal University, Guiyang, Guizhou, 550001, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
Phytochemistry. 2021 Apr;184:112655. doi: 10.1016/j.phytochem.2021.112655. Epub 2021 Feb 1.
Petal blight caused by fungi is among the most destructive diseases of Rhododendron, especially Rhododendron agastum. Nonetheless, the metabolite changes that occur during petal blight are unknown. We used untargeted gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) and ultra-high performance liquid chromatography quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS) to compare the metabolite profiles of healthy and petal blight R. agastum flowers. Using GC-TOF-MS, 571 peaks were extracted, of which 189 metabolites were tentatively identified. On the other hand, 364 and 277 metabolites were tentatively identified in the positive and negative ionization modes of the UHPLC-QTOF-MS/MS, respectively. Principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA) were able to clearly discriminate between healthy and petal blight flowers. Differentially abundant metabolites were primarily enriched in the biosynthesis of specialized metabolites. 17 accumulated specialized metabolites in petal blight flowers have been reported to have antifungal activity, and literature indicates that 9 of them are unique to plants. 3 metabolites (chlorogenic acid, medicarpin, and apigenin) are reportedly involved in resistance to blight caused by pathogens. We therefore speculate that the accumulation of chlorogenic acid, medicarpin, and apigenin may be involved in the resistance to petal blight. Our results suggest that these metabolites may be used as candidate biocontrol agents for the control fungal petal blight in Rhododendron.
花瓣疫病是由真菌引起的，是对杜鹃花，尤其是对羊踯躅危害最大的疾病之一。然而，花瓣疫病过程中发生的代谢变化尚不清楚。我们使用非靶向气相色谱飞行时间质谱（GC-TOF-MS）和超高效液相色谱四极杆飞行时间串联质谱（UHPLC-QTOF-MS/MS）比较了健康和花瓣疫病羊踯躅花的代谢谱。使用 GC-TOF-MS 提取了 571 个峰，其中 189 个代谢物被暂定鉴定。另一方面，在 UHPLC-QTOF-MS/MS 的正、负离子模式下分别暂定鉴定出 364 和 277 种代谢物。主成分分析（PCA）和正交偏最小二乘判别分析（OPLS-DA）能够清楚地区分健康和花瓣疫病花。差异丰度代谢物主要富集在次生代谢物的生物合成中。17 种在花瓣疫病花中积累的特殊代谢物已被报道具有抗真菌活性，文献表明其中 9 种是植物特有的。3 种代谢物（绿原酸、美迪紫檀素和芹菜素）据报道参与了对病原体引起的疫病的抗性。因此，我们推测绿原酸、美迪紫檀素和芹菜素的积累可能与花瓣疫病的抗性有关。我们的研究结果表明，这些代谢物可能可作为杜鹃花真菌花瓣疫病生物防治的候选物。
