ABSTRACT
Renewable energy resources such as biomass are crucial for a sustainable global society. Trees are a major source of lignocellulosic biomass, which can vary in response to different environmental factors owing to epigenetic regulation, such as DNA C-methylation. To investigate the effects of DNA methylation on plant development and wood formation, and its impacts on gene expression, with a focus on secondary cell wall (SCW)-associated genes, Salix purpurea plantlets were cloned from buds derived from a single hybrid tree for both treatment and control conditions. For the treatment condition, buds were exposed to 50 µM zebularine in vitro and a combined strategy of whole-genome bisulfite sequencing (WGBS) and RNA-seq was employed to examine the methylome and transcriptome profiles of different tissues collected at various time points under both conditions. Transcriptomic and methylome data revealed that most of the promoter and gene body demethylation had no marked effects on the expression profiles of genes. Nevertheless, gene expression tended to decrease with the increased methylation levels of genes with highly methylated promoters. Results indicated that demethylation is less evident in centromeric regions and sex chromosomes. Promoters of secondary cell wall-associated genes, such as 4-coumarate-CoA ligase-like and Rac-like GTP-binding protein RHO, were differentially methylated in the secondary xylem samples collected from two-month potted treated plants compared to control samples. Our results provide novel insights into DNA methylation and gene expression landscapes and a basis for investigating the epigenetic regulation of wood formation in S. purpurea as a model plant for bioenergy species.
Subject(s)
Cytidine , DNA Methylation , Gene Expression Regulation, Plant , Salix , Transcriptome , DNA Methylation/drug effects , DNA Methylation/genetics , Cytidine/analogs & derivatives , Cytidine/pharmacology , Cytidine/genetics , Transcriptome/genetics , Transcriptome/drug effects , Salix/genetics , Salix/drug effects , Gene Expression Regulation, Plant/drug effects , Genome, Plant/genetics , Cell Wall/metabolism , Cell Wall/drug effects , Cell Wall/genetics , Epigenesis, Genetic/drug effectsABSTRACT
Introduction: DNA methylation plays major roles in the epigenetic regulation of gene expression, transposon and transcriptional silencing, and DNA repair, with implications in developmental processes and phenotypic plasticity. Relevantly for woody species, DNA methylation constitutes a regulative layer in cell wall dynamics associated with xylogenesis. The use of methyltransferase and/or demethylase inhibitors has been proven informative to shed light on the methylome dynamics behind the regulation of these processes. Methods: The present work employs the cytidine analog zebularine to inhibit DNA methyltransferases and induce DNA hypomethylation in Salix purpurea plantlets grown in vitro and in soil. An integrative approach was adopted to highlight the effects of zebularine on proteomic dynamics, revealing age-specific (3 weeks of in vitro culture and 1 month of growth in soil) and tissue-specific (stem and root) effects. Results and discussion: After 3 weeks of recovery from zebularine treatment, a decrease of 5-mC levels was observed in different genomic contexts in the roots of explants that were exposed to zebularine, whereas a functionally heterogeneous subset of protein entries was differentially accumulated in stem samples, including entries related to cell wall biosynthesis, tissue morphogenesis, and hormonal regulation. Significant proteomic remodeling was revealed in the development from in vitro to in-soil culture, but no significant changes in 5-mC levels were observed. The identification of tissue-specific proteomic hallmarks in combination with hypomethylating agents provides new insights into the role of DNA methylation and proteome in early plant development in willow species. Proteomic data are available via ProteomeXchange with identifier PXD045653. WGBS data are available under BioProject accession PRJNA889596.
ABSTRACT
Thermoplastic starch (TPS) is a homogenous material prepared from native starch and water or other plasticizers subjected to mixing at a temperature exceeding starch gelatinization temperature. It shows major drawbacks like high moisture sensitivity, poor mechanical properties, and thermal stability. To overcome these drawbacks without significant cost increase, TPS could be blended with bio-based or biodegradable polymers and filled with plant-based fillers, beneficially waste-based, like brewers' spent grain (BSG), the main brewing by-product. Filler modifications are often required to enhance the compatibility of such composites. Herein, we investigated the impact of BSG thermomechanical and chemical treatments on the structure, physical, thermal, and rheological performance of Mater-Bi-based composites. Thermomechanical modifications enhanced matrix thermal stability under oxidative conditions delaying degradation onset by 33 °C. Moreover, BSG enhanced the crystallization of the polybutylene adipate terephthalate (PBAT) fraction of Mater-Bi, potentially improving mechanical properties and shortening processing time. BSG chemical treatment with isophorone diisocyanate improved the processing properties of the composites, expressed by a 33% rise in melt flow index. Depending on the waste filler's selected treatment, processing, and rheological performance, thermal stability or interfacial adhesion of composites could be enhanced. Moreover, the appearance of the final materials could be adjusted by filler selection.
ABSTRACT
Willow bark is one of the few plant raw materials which contain natural active substances that have analgesic, fever-reducing, anti-inflammatory and anti-rheumatic effects. Salix purpurea, listed as widespread and common in many countries, belongs to the willow species with the highest content of salicylic compounds. The chemical composition and content of major salicylic glycosides (SGs) in the bark of S. purpurea genotypes from natural locations were investigated in this study to evaluate their applicability for pharmaceutical processing and creative breeding. Secondary metabolites were analyzed in bark extracts from 91 genotypes of S. purpurea selected from natural locations. The bark of all analyzed genotypes contained salicylic glycosides: salicin, salicortin and tremulacin; flavanones: naringenin 5-O-glucoside, naringenin 7-O-glucoside, naringenin, chalcone isosalipurposide and flavan-3-ol: catechin. Picein and populin were detected in 10% of the studied genotypes. The SG content of purple willow bark ranged from 3.04 to 10.96, pointing to high variations between S. purpurea genotypes. This study provides valuable breeding material and offers attractive prospects for the breeding of new and improved willow varieties. Varieties with the most desirable traits, grown under controlled conditions, can supply high-quality herbal materials for the pharmaceutical industry.