Secondary development in the stem: when Arabidopsis and trees are closer than it seems

Barra-Jiménez, Azahara; Ragni, Laura

doi:10.1016/j.pbi.2016.12.002

Cited by 36 publications

(24 citation statements)

References 65 publications

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“…Different transcriptomic approaches have been employed to reveal complex regulatory mechanisms and genes behind secondary xylem development (Carvalho et al, 2013;Nakano et al, 2015;Raherison et al, 2015;Zhong and Ye, 2015;Lamara et al, 2016;Barra-Jiménez and Ragni, 2017;Jokipii-Lukkari et al, 2017. Microarray and mRNA sequencing (RNA-Seq) approaches have identified a set of genes involved in cell wall polysaccharide and lignin synthesis as essential for cell wall morphology, composition, and wood quality.…”

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confidence: 99%

Ray Parenchymal Cells Contribute to Lignification of Tracheids in Developing Xylem of Norway Spruce

et al. 2019

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A comparative transcriptomic study and a single-cell metabolome analysis were combined to determine whether parenchymal ray cells contribute to the biosynthesis of monolignols in the lignifying xylem of Norway spruce (Picea abies). Ray parenchymal cells may function in the lignification of upright tracheids by supplying monolignols. To test this hypothesis, parenchymal ray cells and upright tracheids were dissected with laser-capture microdissection from tangential cryosections of developing xylem of spruce trees. The transcriptome analysis revealed that among the genes involved in processes typical for vascular tissues, genes encoding cell wall biogenesis-related enzymes were highly expressed in both developing tracheids and ray cells. Interestingly, most of the shikimate and monolignol biosynthesis pathway-related genes were equally expressed in both cell types. Nonetheless, 1,073 differentially expressed genes were detected between developing ray cells and tracheids, among which a set of genes expressed only in ray cells was identified. In situ single cell metabolomics of semi-intact plants by picoliter pressure probe-electrospray ionization-mass spectrometry detected monolignols and their glycoconjugates in both cell types, indicating that the biosynthetic route for monolignols is active in both upright tracheids and parenchymal ray cells. The data strongly support the hypothesis that in developing xylem, ray cells produce monolignols that contribute to lignification of tracheid cell walls.

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confidence: 99%

Ray Parenchymal Cells Contribute to Lignification of Tracheids in Developing Xylem of Norway Spruce

et al. 2019

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“…The gradient of stiffness in adaxial cortical cell walls follows a secondary cell wall developmental (SCW) gradient in which walls become thicker and increasingly lignified moving from stem tip to base, as reported in monocots such as bamboo, and eudicots such as A. thaliana and various tree species 37,38,41 . This type of stiffness gradient allows the upper portions of stems/trunks/culms to be flexible and bend more readily in response to environmental factors such as wind, while the stiffer base resists movement and prevents the plant from being uprooted [42][43][44] .…”

Section: Resultsmentioning

confidence: 79%

“…These perpendicular gradients likely result from established SCW developmental gradients (e.g., increasing stem tip to base lignification [ Fig. 2] and cell wall thickness), and separate adaxial and abaxial differentiation programs 37,38,41 . S. lepidophylla has provided the opportunity to study three-dimensional gradients at small length scales that lead to macro-level actuation.…”

Section: Discussionmentioning

confidence: 99%

Nano-indentation reveals a potential role for gradients of cell wall stiffness in directional movement of the resurrection plant Selaginella lepidophylla

Asgari

Brulé

Western

et al. 2020

Sci Rep

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Stiffness, defined as the ability of a material to resist deformation in response to an applied stress, determines the direction and extent of conformational changes undertaken by a material and hence is a critical mechanical property governing actuation response. The stiffer a material is, the less it deforms under a mechanical load. By layering or otherwise locally joining materials with dissimilar stiffness in a composite material, it is possible to control the global deformation in a specific direction 14,15. Stiffness profiles leading to deformation in S. lepidophylla have been studied at the organ and tissue level 10,11. Here, we present a complementary nanoscale investigation that sheds light on previously unexplored factors controlling the stiffness of S. lepidophylla in static and time-varying loads. The specific focus is on the elastic moduli of cortical cell walls, and the aim is to understand their contribution to the observed direction and degree of curling of inner stems. We take advantage of atomic force microscopy (AFM), a technique frequently used to study plant cell wall mechanics 16-18. In particular, we use AFM indentation to locally measure the nanoscale elastic properties of cell walls, as well as to assess the level of inhomogeneity and stiffness gradients of the tissue across representative transverse sections of the plant, both longitudinally (stem tip to base) and between adaxial and abaxial stem sides. We also preliminarily investigate the viscoelastic behaviour at given loading rates. Materials and Methods Plant materials. Mature S. lepidophylla plants were purchased from Canadian Air Plants (New Brunswick, Canada), and maintained in a desiccated state at 25 °C and ~30-50% relative humidity until use. Prior to experimentation, S. lepidophylla plants were placed in a plate of water and allowed to rehydrate for three consecutive days to achieve 100% relative water content. Time-lapse video capture. Video capture was adapted from the protocol in Rafsanjani et al. 10. Time-lapse videos were captured using a Logitech C920 HD Pro Webcam (1080p, Carl Zeiss optics) and Video Velocity Time-Lapse Studio software (Candylabs). S. lepidophylla plants were allowed to rehydrate for 24 hours. Individual inner stems were cut from the plant at the root-stem interface and secured in a metal clamp, which was affixed to the base of a square Petri dish. Stems were then allowed to air-dry for approximately 6 hours, during which time changes in their curvature were captured via time-lapse filming at frame rate of 1 min 21 s. Stems were taken from four different S. lepidophylla plants. In total, four inner stems were tested and displayed similar curling/uncurling patterns.

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“…Comparative analysis of the wox4 pxy, wox14 pxy and wox4 wox14 double mutants have also indicated that their regulation differs in Arabidopsis (Hirakawa et al ., ; Ji et al ., ). As many signaling pathways with a WOX gene also include a CLE/PXY‐like ligand/receptor (Barra‐Jimenez and Ragni, ), we can propose a regulatory model in Arabidopsis where an additional xylem promotor signal (CLE/PXY‐like) also controls the expression of WOX14 to promote GA production for optimizing vascular cell differentiation during wood formation, and overcomes the CLE41/PXY/WOX4 signal implicated in cambial stem cell proliferation (Figure ).…”

Section: Discussionmentioning

confidence: 99%

WOX14 promotes bioactive gibberellin synthesis and vascular cell differentiation in Arabidopsis

et al. 2017

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Procambial and cambial stem cells provide the initial cells that allow the formation of vascular tissues. WOX4 and WOX14 have been shown to act redundantly to promote procambial cell proliferation and differentiation. Gibberellins (GAs), which have an important role in wood formation, also stimulate cambial cell division. Here we show that the loss of WOX14 function phenocopies some traits of GA-deficient mutants that can be complemented by exogenous GA application, whereas WOX14 overexpression stimulates the expression of GA3ox anabolism genes and represses GA2ox catabolism genes, promoting the accumulation of bioactive GA. More importantly, our data clearly indicate that WOX14 but not WOX4 promotes vascular cell differentiation and lignification in inflorescence stems of Arabidopsis.

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Secondary development in the stem: when Arabidopsis and trees are closer than it seems

Cited by 36 publications

References 65 publications

Ray Parenchymal Cells Contribute to Lignification of Tracheids in Developing Xylem of Norway Spruce

Ray Parenchymal Cells Contribute to Lignification of Tracheids in Developing Xylem of Norway Spruce

Nano-indentation reveals a potential role for gradients of cell wall stiffness in directional movement of the resurrection plant Selaginella lepidophylla

WOX14 promotes bioactive gibberellin synthesis and vascular cell differentiation in Arabidopsis

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