A Comparative Analysis of Transcription Networks Active in Juvenile and Mature Wood in Populus

Abstract

Juvenile wood (JW) and mature wood (MW) have distinct physical and chemical characters, resulting from wood formation at different development phases over tree lifespan. However, the regulatory mechanisms that distinguish or modulate the characteristics of JW and MW in relation to each other have not been mapped. In this study, by employing the Populus trees with an identical genetic background, we carried out RNA sequencing (RNA-seq) and whole genome bisulfite sequencing (WGBS) in JW and MW forming tissue and analyzed the transcriptional programs in association with the wood formation in different phrases. JW and MW of Populus displayed different wood properties, including higher content of cellulose and hemicelluloses, less lignin, and longer and larger fiber cells and vessel elements in MW as compared with JW. Significant differences in transcriptional programs and patterns of DNA methylation were detected between JW and MW. The differences were concentrated in gene networks involved in regulating hormonal signaling pathways responsible for auxin distribution and brassinosteroids biosynthesis as well as genes active in regulating cell expansion and secondary cell wall biosynthesis. An observed correlation between gene expression profiling and DNA methylation indicated that DNA methylation affected expression of the genes related to auxin distribution and brassinosteroids signal transduction, cell expansion in JW, and MW formation. The results suggest that auxin distribution, brassinosteroids biosynthesis, and signaling be the critical molecular modules in formation of JW and MW. DNA methylation plays a role in formatting the molecular modules which contribute to the transcriptional programs of wood formation in different development phases. The study sheds light into better understanding of the molecular networks underlying regulation of wood properties which would be informative for genetic manipulation for improvement of wood formation.

Mechanical characterisation of the developing cell wall layers of tension wood fibres by Atomic Force Microscopy

“…These low values can be partly explained by the young age of the tree used in our study (less than 3-month old). Indeed, the juvenile wood is known for its high microfibril angle (MFA) in the S2-layer and its low cellulose content (Luo et al, 2021). The values of the indentation modulus in the G-layer of a mature cell increased to around 18.3±3.1 GPa on average (see Fig.…”

Revealing the transitory and local effect of zebularine on development and on proteome dynamics of Salix purpurea

“…Considering arboreal species, DNA methylation dynamics are reportedly involved into developmental processes such as the regulation of bud dormancy, acclimation, and biomass production (e.g., in Populus × euramericana , Le Gac et al., 2018 ). More specifically, differential DNA methylation is involved into cell wall development, cell division, and cell expansion in several woody species, including Populus trichocarpa ( Zhang et al., 2020 ), Populus deltoides × P. euramericana ( Luo et al., 2021 ), and Populus tomentosa ( Chen et al., 2021 ). Compatibly, the inhibition of DNA methylation by 5-azacytidine resulted into impaired cell wall synthesis, as shown in, e.g., in Phyllostachys edulis ( Liufu et al., 2023 ).…”

Methylation of microRNA genes and its effect on secondary xylem development of stem in poplar

“…The methylation‐sensitive amplification polymorphism analysis showed that DNA methylation might contribute to regulating tree growth and wood property traits of P. tomentosa (Ma et al., 2020). DNA methylation affected expression of the genes related to cell expansion in juvenile wood and mature wood formation (Luo et al., 2021). The DNA methylation level significantly increased from the juvenile phase to mature phase in Pinus radiate (Fraga et al., 2002).…”