scholarly journals Vascular Cambium: The Source of Wood Formation

2021 ◽  
Vol 12 ◽  
Author(s):  
Dian Wang ◽  
Yan Chen ◽  
Wei Li ◽  
Quanzi Li ◽  
Mengzhu Lu ◽  
...  

Wood is the most abundant biomass produced by land plants and is mainly used for timber, pulping, and paper making. Wood (secondary xylem) is derived from vascular cambium, and its formation encompasses a series of developmental processes. Extensive studies in Arabidopsis and trees demonstrate that the initiation of vascular stem cells and the proliferation and differentiation of the cambial derivative cells require a coordination of multiple signals, including hormones and peptides. In this mini review, we described the recent discoveries on the regulation of the three developmental processes by several signals, such as auxin, cytokinins, brassinosteroids, gibberellins, ethylene, TDIF peptide, and their cross talk in Arabidopsis and Populus. There exists a similar but more complex regulatory network orchestrating vascular cambium development in Populus than that in Arabidopsis. We end up with a look at the future research prospects of vascular cambium in perennial woody plants, including interfascicular cambium development and vascular stem cell regulation.

Botany ◽  
2015 ◽  
Vol 93 (4) ◽  
pp. 211-220 ◽  
Author(s):  
Arno Fritz das Neves Brandes ◽  
Claudio Sergio Lisi ◽  
Leonardo Davi S.A.B. da Silva ◽  
Kishore S. Rajput ◽  
Cláudia Franca Barros

Cambial activity and the formation of secondary xylem were investigated in the main stem of three arboreal leguminous species and one liana. To compare the seasonal vascular cambium behavior of these species, two methods were concurrently applied: induction of injury in the vascular cambium and anatomical analysis of the vascular cambium and adjacent zones (differentiation zone). One tree species, Pseudopiptadenia contorta (DC.) G.P.Lewis & M.P.Lima, was sampled in three forest formations: alluvial, submontane, and montane. Two more tree species, Apuleia leiocarpa (Vogel) J.F.Macbr. and Pseudopiptadenia leptostachya (Benth.) Rauschert, were sampled in submontane and montane forest, respectively. Dalbergia frutescens (Vell.) Britton var. frutescens, a liana, was sampled in montane forest. All species investigated showed distinctive formation of annual growth rings. Reactivation of the vascular cambium was observed at the end of spring, and it remained active during the summer. Thereafter, cambial activity either ceased or declined dramatically at the end of autumn. Similar to the tree species studied, cambial activity in D. frutescens var. frutescens showed similar seasonal cambial activity throughout the year. Based on both direct and indirect methods, our results showed that cambial activity and wood formation only occurred during the rainy season, suggesting the potential of these species for use in dendrochronological studies.


2021 ◽  
Author(s):  
Yayu Guo ◽  
Huimin Xu ◽  
Hongyang Wu ◽  
Weiwei Shen ◽  
Jinxing Lin ◽  
...  

Abstract Understanding the changing patterns of vascular cambium during seasonal cycles is crucial to reveal the mechanisms that control cambium activity and wood formation, but this area has been underexplored, especially in conifers. Here, we quantified the changing cellular morphology patterns of cambial zones during the active, transition and dormant stages. With the help of toluidine blue and periodic acid Schiff staining to visualize cell walls and identify their constituents, we observed decreasing cambial cell layers, thickening of newly formed xylem cell walls and increased polysaccharide granules in phloem from June to the following March over the course of our collecting period. Pectin immunofluorescence showed that dormant stage cambium can produce highly abundant de-esterified homogalacturonan and (1–4)-β-D-galactan epitopes, while active cambium can strong accumulate high methylesterified homogalacturonan. Calcofluor white staining and confocal Raman spectroscopy analysis revealed regular changes in the chemical composition of cell walls, such as relative lower cellulose deposition in transition stage in vascular cambium, and higher lignin accumulation was found in dormant stage in secondary xylem. Moreover, RT-qPCR analysis suggested that various IAA (Aux/IAA protein), CesA, CslA and HDZ genes, as well as NAC, PME3 and PME4, may be involved in cambium activities and secondary xylem formation. Taken together, these findings provide new information about cambium activity and cell differentiation in the formation, structure, and chemistry in conifers during the active–dormant transition.


2020 ◽  
Author(s):  
Arezoo Rahimi ◽  
Omid Karami ◽  
Angga Dwituti Lestari ◽  
Dongbo Shi ◽  
Thomas Greb ◽  
...  

AbstractPlant secondary growth, also referred to as wood formation, includes the production of secondary xylem, which is derived from meristematic cambium cells embedded in vascular tissues. Despite the importance of secondary xylem in plant growth and wood formation, the molecular mechanism of secondary growth is not yet well understood. Here we identified an important role for the Arabidopsis thaliana (Arabidopsis) AT-HOOK MOTIF CONTAINING NUCLEAR LOCALIZED 15 (AHL15) gene, encoding for a putative transcriptional regulator, in controlling vascular cambium activity and secondary xylem formation. Secondary xylem development was significantly reduced in inflorescence stems of the Arabidopsis ahl15 loss-of-function mutant, whereas AHL15 overexpression led to extensive secondary xylem formation. AHL15 expression under a vascular meristem-specific promoter also enhanced the amount of interfascicular secondary xylem. Moreover, AHL15 appeared to be required for the enhanced secondary xylem formation in the Arabidopsis double loss-of-function mutant of the SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1) and FRUITFULL (FUL) genes. A well-known central regulator of cambial activity is the plant hormone cytokinin. We showed that the expression of two cytokinin biosynthesis genes (ISOPENTENYL TRANSERASE (IPT) 3 and 7) is decreased in ahl15 loss-of-function mutant stems, whereas the secondary xylem deficiency in these mutant stems can be resorted by cambium-specific expression of the Agrobacterium tumefaciens IPT gene, indicating that AHL15 acts through the cytokinin pathway. These findings support a model whereby AHL15 acts as a central factor inducing vascular cambium activity downstream of SOC1 and FUL and upstream of IPT3, IPT7 and LOG4, LOG5 governing the rate of secondary xylem formation in Arabidopsis inflorescence stems.


2019 ◽  
Vol 11 (7) ◽  
pp. 1986-1996 ◽  
Author(s):  
Danielle Roodt ◽  
Zhen Li ◽  
Yves Van de Peer ◽  
Eshchar Mizrachi

Abstract Woodiness (secondary xylem derived from vascular cambium) has been gained and lost multiple times in the angiosperms, but has been lost ancestrally in all monocots. Here, we investigate the conservation of genes involved in xylogenesis in fully sequenced angiosperm genomes, hypothesizing that monocots have lost some essential orthologs involved in this process. We analyzed the conservation of genes preferentially expressed in the developing secondary xylem of two eudicot trees in the sequenced genomes of 26 eudicot and seven monocot species, and the early diverging angiosperm Amborella trichopoda. We also reconstructed a regulatory model of early vascular cambial cell identity and differentiation and investigated the conservation of orthologs across the angiosperms. Additionally, we analyzed the genome of the aquatic seagrass Zostera marina for additional losses of genes otherwise essential to, especially, secondary cell wall formation. Despite almost complete conservation of orthology within the early cambial differentiation gene network, we show a clear pattern of loss of genes preferentially expressed in secondary xylem in the monocots that are highly conserved across eudicot species. Our study provides candidate genes that may have led to the loss of vascular cambium in the monocots, and, by comparing terrestrial angiosperms to an aquatic monocot, highlights genes essential to vasculature on land.


IAWA Journal ◽  
1986 ◽  
Vol 7 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Nobuo Yoshizawa ◽  
Yujiro Tanaka ◽  
Toshinaga Idei

In the course of the righting movement in young spruce trees (Picea jezoensis Carr. var. hondoensis Rehd.) inclined at 45°, the occurrence of compression wood associated with the development of vascular cambium in the shoot was observed. In shoots, the recovery first took place at the mid point, a few days after inclination. The observations of serial cross sections taken from the apex downward revealed no appreciable difference in the development of the procambium-cambium continuum between the upper- and underside of the shoot. The formation and structure of primary tracheary elements were similar, irrespective of the site of the procambium in the shoot. No compression wood cells occurred before the vascular cambium cylinder was complete. The stimulus of compression wood formation is received only by the differentiating secondary xylem tissues derived from the cambium cylinder.


Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1002
Author(s):  
Shenquan Cao ◽  
Cong Wang ◽  
Huanhuan Ji ◽  
Mengjie Guo ◽  
Jiyao Cheng ◽  
...  

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.


IAWA Journal ◽  
2021 ◽  
pp. 1-16
Author(s):  
Bei Luo ◽  
Arata Yoshinaga ◽  
Tatsuya Awano ◽  
Keiji Takabe ◽  
Takao Itoh

Abstract We studied the time-course of stem response for six months following complete girdling in branches of Aquilaria sinensis to determine the potential role of interxylary phloem (IP) in this response. It was found that the vascular cambium, as well as its derivative secondary xylem and phloem, regenerated fully through redifferentiation of IP. We confirmed that vascular cambium regenerated within one month after girdling based on observation of new vessels, IP, and secondary phloem fibers. The time-course study showed that IPs made connections with each other, merged, and became larger through the proliferation of IPs parenchyma cells and the cleaving of secondary xylem in a narrow zone 400 to 1000 μm deep inside the girdled edge. This led to the formation of a complete circular sheath of vascular cambium, followed by the regeneration of vascular tissue. It is worth noting that the secondary xylem is regenerated always following the formation of a thick belt of wound xylem.


Genes ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 619 ◽  
Author(s):  
Zhenhao Guo ◽  
Hui Hua ◽  
Jin Xu ◽  
Jiaxing Mo ◽  
Hui Zhao ◽  
...  

Cryptomeria fortunei, also known as the Chinese cedar, is an important timber species in southern China. The primary component of its woody tissues is lignin, mainly present in secondary cell walls. Therefore, continuous lignin synthesis is crucial for wood formation. In this study, we aimed to discover key genes involved in lignin synthesis expressed in the vascular cambium of C. fortunei. Through transcriptome sequencing, we detected expression of two genes, 4CL and CCoAOMT, known to be homologous to enzymes involved in the lignin synthesis pathway. We studied the function of these genes through bioinformatics analysis, cloning, vascular cambium expression analysis, and transgenic cross-species functional validation studies. Our results show that Cf4CL and CfCCoAOMT do indeed function in the pathway of lignin synthesis and likely perform this function in C. fortunei. They are prime candidates for future (gene-editing) studies aimed at optimizing C. fortunei wood production.


Endocrinology ◽  
2019 ◽  
Vol 160 (12) ◽  
pp. 2969-2980 ◽  
Author(s):  
Marietta R Easterling ◽  
Kristin M Engbrecht ◽  
Erica J Crespi

Abstract Studies aiming to uncover primary mechanisms of regeneration have predominantly focused on genetic pathways regulating specific stages in the regeneration process: wound healing, blastema formation, and pattern formation. However, studies across organisms show that environmental conditions and the physiological state of the animal can affect the rate or quality of regeneration, and endocrine signals are likely the mediators of these effects. Endocrine signals acting directly on receptors expressed in the tissue or via neuroendocrine pathways can affect regeneration by regulating the immune response to injury, allocation of energetic resources, or by enhancing or inhibiting proliferation and differentiation pathways involved in regeneration. This review discusses the cumulative knowledge in the literature about endocrine regulation of regeneration and its importance in future research to advance biomedical research.


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