Relationship between metabolites variation and Paulownia witches' broom.

Abstract

Objective Paulownia witches' broom caused by phytoplasma can lead to severe damage to the survival and wood production of Paulownia trees, which can result in a significant economic loss. This study aims to explore the relationship between metabolites variation and Paulownia witches' broom using metabolomic analysis. Method High performance liquid chromatography-mass spectrometry (HPLC-MS) were used to analyze variation in the metabolite of healthy and phytoplasma-infected Paulownia tomentosa seedlings, differentially expressed m/z peaks were selected using principal component analysis and partial least squares-discriiminate analysis, then the differentially expressed m/z peaks detected by MS were mapped to KEGG metabolites database to find the changes of metabolite content and species in response to phytoplasma infection. Result The result showed that 1 612 metabolites were differentially expressed, among which 765 metabolites have a decreased concentration in phytoplasma-infected seedlings compared to healthy seedlings, and 847 metabolites are on the contrary. KEGG pathway analysis showed that 460 differentially expressed metabolites were mapped to 111 KEGG pathways. The most significantly represent category among the assigned pathways was 'isoquinoline alkaloid biosynthesis', followed by 'diterpenoid biosynthesis' and 'flavonoid biosynthesis'. Metabolites which are involved in plant hormones signal transduction and flavonoid biosynthesis were identified to be related to plant's response to phytoplasma infection. Among them, the concentrations of zeatin, zeatin riboside, gibberellin, dihydrozeatin riboside, pelargonidin, apigenin and cyanidin changed significantly in phytoplasma-infected seedlings compared with the healthy ones, suggesting that variations in concentrations of these metabolites might be related to PaWB. Conclusion Variation in metabolite concentrations among the healthy and phytoplasma-infected seedlings can help reveal the candidate metabolites and inherent pathways that are potentially involved in PaWB. This study will provide new insight into the role of metabolites in Paulownia and other trees in response to phytoplasma infection.