Transcriptomic, Proteomic, and Metabolic Profiles of Catalpa bungei Tension Wood Reveal New Insight Into Lignin Biosynthesis Involving Transcription Factor Regulation

Abstract

Lignin is a complex polymer in plant cell walls whose proportion is second only to that of cellulose and plays an important role in the mechanical properties of wood and stress resistance of plants. Here, we induced tension wood (TW) formation in Catalpa bungei by artificial bending and analyzed the lignin metabolism of the TW. LC-MS analysis showed that a significantly higher content of coniferyl aldehyde was observed in the TW cell wall than in the opposite wood (OW) and normal wood (NW) cell walls. TW had significantly lower contents of coniferyl alcohol than OW and NW. Raman spectroscopy results indicated that TW had lower total lignin than OW and NW. The transcription and translation levels of most of the differentially expressed genes (DEGs) involved in lignin monomer biosynthesis indicated upregulation in TW/OW and TW/NW. We found no significant difference in the transcription levels of three collision gases (CADs) between TW and OW or between NW, but their translation levels were significantly downregulated in TW, suggesting post-transcriptional control for CAD. We predicted and analyzed transcription factors that could target DEGs involved in lignin monomer biosynthesis in TW. Based on the analysis of the relationships of targeting and coexpression, we found that NAC (evm.model.group1.695) could potentially target 4CLs and CCoAOMT, that HD-Zip (evm.model.group7.1157) had potential targeting relationships with CCoAOMT, F5H, and CCR, and that their expression levels were significantly positive. It is speculated that the upregulation of NAC and HD-ZIP transcription factors activates the expression of downstream target genes, which leads to a significant increase in coniferyl aldehyde in TW. However, the decrease in total lignin in TW may be caused by the significant downregulation of CAD translation and the significant decrease in precursors (coniferyl alcohol). Whether the expression of CAD genes is regulated by post-transcriptional control and affects TW lignin metabolism needs further study.

Integrated transcriptomic and metabolic analyses provide insights into the maintenance of embryogenic potential and the biosynthesis of phenolic acids and flavonoids involving transcription factors in Larix kaempferi (Lamb.) Carr.

“…The regulatory relationship between candidate TFs and the seven target genes was shown in Figure 9 . The node degree of TFs was defined as the number of target genes one TF may regulate, which could represent the importance of TFs in the metabolic pathway ( Xiao et al., 2021 ). The results showed that each TF had several target genes with a node degree ranging from 1 to 5 ( Table 4 ; Figure 9 ).…”

“…Similar to transcriptomics or proteomics, metabolomics is an emerging omics technology aimed at identifying and quantifying endogenous molecule metabolites, the final products of cell biological regulation process ( Lin et al., 2020 ). In recent years, “multi-omics” strategies have provided new insights in revealing underlying mechanisms in plant growth and development as well as in plant responses to external stresses ( Xiao et al., 2021 ; Zhang et al., 2021c ; Li et al., 2022a ; Wang et al., 2022b ). The combined analysis of transcriptome and metabolome data can be used to predict the gene function involved in the targeted metabolic pathway and simultaneously provide supporting information for gene mining ( Fukushima et al., 2009 ).…”

Seasonal Developing Xylem Transcriptome Analysis of Pinus densiflora Unveils Novel Insights for Compression Wood Formation

“…In contrast, TW formation in angiosperms has a high cellulose content and is formed in the upper side of an inclination of a stem [ 12 ]. Recently, many studies have been conducted on TW formation in various angiosperm species, including Catalpa bungee , Populus trichocarpa , Hevea brasiliensis , and Betula luminifera , to understand the underlying molecular mechanisms and identify essential genes [ 14 , 15 , 16 , 17 , 18 ]. Previously, Sato et al [ 19 ] reported transcriptome analysis of reaction wood formation from Chamaecyparis obtusa .…”