Quantitative proteome-level analysis of paulownia witches’ broom disease with methyl methane sulfonate assistance reveals diverse metabolic changes during the infection and recovery processes

Abstract

Paulownia witches’ broom (PaWB) disease caused by phytoplasma is a fatal disease that leads to considerable economic losses. Although there are a few reports describing studies of PaWB pathogenesis, the molecular mechanisms underlying phytoplasma pathogenicity in Paulownia trees remain uncharacterized. In this study, after building a transcriptome database containing 67,177 sequences, we used isobaric tags for relative and absolute quantification (iTRAQ) to quantify and analyze the proteome-level changes among healthy P. fortunei (PF), PaWB-infected P. fortunei (PFI), and PaWB-infected P. fortunei treated with 20 mg L−1 or 60 mg L−1 methyl methane sulfonate (MMS) (PFI-20 and PFI-60, respectively). A total of 2,358 proteins were identified. We investigated the proteins profiles in PF vs. PFI (infected process) and PFI-20 vs. PFI-60 (recovered process), and further found that many of the MMS-response proteins mapped to “photosynthesis” and “ribosome” pathways. Based on our comparison scheme, 36 PaWB-related proteins were revealed. Among them, 32 proteins were classified into three functional groups: (1) carbohydrate and energy metabolism, (2) protein synthesis and degradation, and (3) stress resistance. We then investigated the PaWB-related proteins involved in the infected and recovered processes, and discovered that carbohydrate and energy metabolism was inhibited, and protein synthesis and degradation decreased, as the plant responded to PaWB. Our observations may be useful for characterizing the proteome-level changes that occur at different stages of PaWB disease. The data generated in this study may serve as a valuable resource for elucidating the pathogenesis of PaWB disease during phytoplasma infection and recovery stages.

Regulation of Long Noncoding RNAs Responsive to Phytoplasma Infection in Paulownia tomentosa

“…All these results suggested the significant role of PsbR in PSII system. Moreover, a previous study has demonstrated that phytoplasma infection could lead to a decrease content of PsbR [ 81 ], and similar result has also been found in transcriptome and proteome research of phytoplasma-infected Paulownia plant [ 22 , 23 ]. In this study, the expression of the alternative genes, which encodes photosystem II 10 kDa polypeptide (PAU000284.1) and chlorophyll a-b binding protein (PAU002322.1), was also downregulated ( Figure 6 ), while the lncRNAs TCONS_00002625 and TCONS_00019890 were predicted to regulate the expression levels of the genes that encode chlorophyll a-b binding proteins and photosystem II 10 kDa polypeptide, respectively, implying that after phytoplasma infection, lncRNAs may influence the photosynthesis electron transfer chain in Paulownia.…”

“…The molecular basis for the pathogenicity of this disease is still poorly understood. Phytoplasma infection altered the expression of genes and proteins in Paulownia [ 15 – 23 ]; however, these observations were descriptive and an in-depth analysis of phytoplasma Paulownia interactions is lacking. Plants infected by phytoplasmas can produce potent strategies to defend themselves against invasion [ 82 , 83 ].…”

“…However, to date, no clear mechanisms behind its molecular regulation has been found, mostly due to the complexity of PaWB phytoplasma itself and the limitations of current technical methods. With the rapid development of high-throughput “omics” technologies, transcriptome, microRNA (miRNA), proteome, and metabolome data have become available and have been used to analyze variations in Paulownia after phytoplasma infection; as a result, a series of genes, miRNAs, proteins, and metabolites that are potentially related to the occurrence of PaWB have been identified [ 2 , 15 – 23 ]. Despite this, the molecular mechanism of PaWB is still poorly understood.…”

Long Non-Coding RNAs Responsive to Witches’ Broom Disease in Paulownia tomentosa

“…Witches' broom disease occurs in many countries and is the biggest threat to Paulownia production, causing serious economic losses [1,2]. In Paulownia, witches' broom disease has been found in saplings and big trees, and leads to malformations of branch, leaf, stem, and flower, such as witches' broom, yellowing, phloem necrosis, and phyllody, respectively [3,4].…”

“…Rifampicin treatment can make PaWB-infected Paulownia recover to normal morphology [13]. Furthermore, the rapid development of 'omics' has allowed for the investigation of the transcriptomes [3,[14][15][16][17][18], microRNAs (miRNAs), degradomes [19][20][21][22], and proteomes [4,23] of Paulownia species, and the results have revealed changes after PaWB infection at transcriptional, post-transcriptional, and translational levels.…”