Cell wall O-acetyl and methyl esterification patterns of leaves reflected in atmospheric emission signatures of acetic acid and methanol

AbstractPlants emit high rates of methanol (meOH), generally assumed to derive from pectin demethylation, and this increases during abiotic stress. In contrast, less is known about the emission and source of acetic acid (AA). In this study, Populus trichocarpa (California poplar) leaves in different developmental stages were desiccated and quantified for total meOH and AA emissions together with bulk cell wall acetylation and methylation content. While young leaves showed high emissions of meOH (140 μmol m−2) and AA (42 μmol m−2), emissions were reduced in mature (meOH: 69%, AA: 60%) and old (meOH: 83%, AA: 76%) leaves. In contrast, the ratio of AA/meOH emissions increased with leaf development (young: 35%, mature: 43%, old: 82%), mimicking the pattern of O-acetyl/methyl ester ratios of leaf bulk cell walls (young: 35%, mature: 38%, old: 51%), which is driven by an increase in O-acetyl and decrease in methyl ester content with age. The results are consistent with meOH and AA emission sources from cell wall de-esterification, with young expanding tissues producing highly methylated pectin that is progressively demethyl-esterified. We highlight the quantification of AA/meOH emission ratios as a potential tool for rapid phenotype screening of structural carbohydrate esterification patterns.

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Transcriptome-wide identification and characterization of microRNAs in diverse phases of wood formation in Populus trichocarpa

10.21203/rs.3.rs-108245/v1 ◽

2020 ◽

Author(s):

Ruiqi Wang ◽

Mengxuan Ren ◽

Shuanghui Tian ◽

Cong Liu ◽

He Cheng ◽

...

Keyword(s):

Cell Wall ◽

Target Genes ◽

Developmental Stages ◽

Populus Trichocarpa ◽

Wood Formation ◽

Pcr Analysis ◽

Integrated Analysis ◽

Cell Wall Modification ◽

Dynamic Regulation ◽

Genome Wide

Abstract Background: MicroRNAs (miRNAs) are small, non-coding RNAs that have important regulatory functions in plant growth and development. However, the miRNAs that are involved in different developmental stages of tree stems have not been systemically characterized. In this study, we applied miRNA expression profiling method to the Populus trichocarpa trunks of the three distinct developmental stages defined as the primary stem (PS), transitional stem (TS), and secondary stem (SS) to investigate the miRNA species, their dynamic regulation and functions during the transitions of wood formation in different developmental stages at the genome-wide scale by Solexa sequencing.Results: We obtained 892, 872, and 882 known miRNAs and 1,727, 1,723, and 1,597 novel miRNAs, from PS, TS, and SS, respectively. And identified 114, 306, and 152 differentially expressed miRNAs (DE-miRNAs) with 921, 2,639, and 2,042 candidate target genes (CTGs), which formed 158, 855, and 297 DE-miRNA-CTG pairs in PS vs TS, PS vs SS, and TS vs SS , respectively. Among these, 47, 439, and 71 DE-miRNA-CTG pairs showed a significant negative correlation, respectively. Finally, we identified 39, 9, and 92 miRNA-CTG pairs involved in PS, TS, and SS, respectively. These DE-miRNA-CTG pairs in poplar or whose counterparts in other plant species are known to be transcriptional factors or structural genes involved in cell division and differentiation, cell wall modification, secondary cell wall (SCW) biosynthesis, lignification, and programmed cell death processes of wood formation. Moreover, qRT–PCR analysis confirmed that the results of small RNA-seq were robust and reliable and most miRNA-CTG pairs exhibited an inverse correlation.Conclusions: This is the first report on an integrated analysis of genome-wide mRNA and miRNA profiling of diverse phases of wood formation in poplar trunks. We showed that even though miRNAs involved in diverse developmental phases were not in a considerable number, their roles in the regulatory network that govern wood formation during different developmental stages cannot be negligible or underestimated. The information and data obtained in this paper significantly advanced our understanding of these miRNAs and their essential, dynamic and diversified roles as well as functions in diverse phases of wood formation in tree species.

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Transcriptome-wide identification and characterization of microRNAs in diverse phases of wood formation in Populus trichocarpa

G3 Genes|Genome|Genetics ◽

10.1093/g3journal/jkab195 ◽

2021 ◽

Author(s):

Ruiqi Wang ◽

Mengxuan Reng ◽

Shuanghui Tian ◽

Cong Liu ◽

He Cheng ◽

...

Keyword(s):

Cell Wall ◽

Target Genes ◽

Developmental Stages ◽

Process Analysis ◽

Populus Trichocarpa ◽

Secondary Growth ◽

Integrated Analysis ◽

Cell Wall Modification ◽

Individual Mirnas ◽

Mirna Species

Abstract We applied miRNA expression profiling method to Populus trichocarpa stems of the three developmental stages, primary stem (PS), transitional stem (TS), and secondary stem (SS), to investigate miRNA species and their regulation on lignocellulosic synthesis and related processes. We obtained 892, 872, and 882 known miRNAs and 1,727, 1,723, and 1,597 novel miRNAs, from PS, TS, and SS, respectively. Comparisons of these miRNA species among different developmental stages led to the identification of 114, 306, and 152 differentially expressed miRNAs (DE-miRNAs), which had 921, 2,639, and 2,042 candidate target genes (CTGs) in the three respective stages of the same order. Corelation analysis revealed 47, 439, and 71 DE-miRNA-CTG pairs of high negative correlation in PS, TS and SS, respectively. Through biological process analysis, we finally identified 34, 6, and 76 miRNA-CTG pairs from PS, TS, and SS, respectively, and the miRNA target genes in these pairs regulate or participate lignocellulosic biosynthesis related biological processes: cell division and differentiation, cell wall modification, secondary cell wall biosynthesis, lignification, and programmed cell death processes. This is the first report on an integrated analysis of genome-wide mRNA and miRNA profilings during multiple phases of poplar stem development. Our analysis results imply that individual miRNAs modulate secondary growth and lignocellulosic biosynthesis through regulating transcription factors and lignocellulosic biosynthetic pathway genes, resulting in more dynamic promotion, suppression, or regulatory circuits. This study advanced our understanding of many individual miRNAs and their essential, diversified roles in dynamic regulation of secondary growth in woody tree species.

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Functional understanding of secondary cell wall cellulose synthases in Populus trichocarpa via the Cas9/gRNA‐induced gene knockouts

New Phytologist ◽

10.1111/nph.17338 ◽

2021 ◽

Author(s):

Wenjing Xu ◽

Hao Cheng ◽

Siran Zhu ◽

Jiyao Cheng ◽

Huanhuan Ji ◽

...

Keyword(s):

Cell Wall ◽

Secondary Cell Wall ◽

Populus Trichocarpa ◽

Functional Understanding ◽

Gene Knockouts ◽

Cellulose Synthases

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Functional Characterisation of the Poplar Atypical Aspartic Protease Gene PtAP66 in Wood Secondary Cell Wall Deposition

Forests ◽

10.3390/f12081002 ◽

2021 ◽

Vol 12 (8) ◽

pp. 1002

Author(s):

Shenquan Cao ◽

Cong Wang ◽

Huanhuan Ji ◽

Mengjie Guo ◽

Jiyao Cheng ◽

...

Keyword(s):

Cell Wall ◽

Secondary Cell Wall ◽

Fluorescent Protein ◽

Secondary Xylem ◽

Populus Trichocarpa ◽

Wood Formation ◽

Protease Gene ◽

Cellulose Content ◽

Transcription Analysis ◽

Functional Characterisation

Secondary cell wall (SCW) deposition is an important process during wood formation. Although aspartic proteases (APs) have been reported to have regulatory roles in herbaceous plants, the involvement of atypical APs in SCW deposition in trees has not been reported. In this study, we characterised the Populus trichocarpa atypical AP gene PtAP66, which is involved in wood SCW deposition. Transcriptome data from the AspWood resource showed that in the secondary xylem of P. trichocarpa, PtAP66 transcripts increased from the vascular cambium to the xylem cell expansion region and maintained high levels in the SCW formation region. Fluorescent signals from transgenic Arabidopsis plant roots and transiently transformed P. trichocarpa leaf protoplasts strongly suggested that the PtAP66-fused fluorescent protein (PtAP66-GFP or PtAP66-YFP) localised in the plasma membrane. Compared with the wild-type plants, the Cas9/gRNA-induced PtAP66 mutants exhibited reduced SCW thickness of secondary xylem fibres, as suggested by the scanning electron microscopy (SEM) data. In addition, wood composition assays revealed that the cellulose content in the mutants decreased by 4.90–5.57%. Transcription analysis further showed that a loss of PtAP66 downregulated the expression of several SCW synthesis-related genes, including cellulose and hemicellulose synthesis enzyme-encoding genes. Altogether, these findings indicate that atypical PtAP66 plays an important role in SCW deposition during wood formation.

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