Untargeted metabolite profiling of petal blight in field-grown Rhododendron agastum using GC-TOF-MS and UHPLC-QTOF-MS/MS.

Affiliation

Duan SG(1), Hong K(1), Tang M(1), Tang J(1), Liu LX(1), Gao GF(2), Shen ZJ(3), Zhang XM(4), Yi Y(5).
Author information:
(1)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.
(2)State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
(3)Key Laboratory for Subtropical Wetland Ecosystem Research of Ministry of Education, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian, 361005, China.
(4)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. Electronic address: [Email]
(5)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. Electronic address: [Email]

Abstract

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.