Xylem Fibers Research Articles

AspWood: High-Spatial-Resolution Transcriptome Profiles Reveal Uncharacterized Modularity of Wood Formation in Populus tremula.

Trees represent the largest terrestrial carbon sink and a renewable source of ligno-cellulose. There is significant scope for yield and quality improvement in these largely undomesticated species, and efforts to engineer elite varieties will benefit from improved understanding of the transcriptional network underlying cambial growth and wood formation. We generated high-spatial-resolution RNA sequencing data spanning the secondary phloem, vascular cambium, and wood-forming tissues of Populus tremula The transcriptome comprised 28,294 expressed, annotated genes, 78 novel protein-coding genes, and 567 putative long intergenic noncoding RNAs. Most paralogs originating from the Salicaceae whole-genome duplication had diverged expression, with the exception of those highly expressed during secondary cell wall deposition. Coexpression network analyses revealed that regulation of the transcriptome underlying cambial growth and wood formation comprises numerous modules forming a continuum of active processes across the tissues. A comparative analysis revealed that a majority of these modules are conserved in Picea abies The high spatial resolution of our data enabled identification of novel roles for characterized genes involved in xylan and cellulose biosynthesis, regulators of xylem vessel and fiber differentiation and lignification. An associated web resource (AspWood, http://aspwood.popgenie.org) provides interactive tools for exploring the expression profiles and coexpression network.

Physico-Chemical Analysis of the Aerial Parts of Diplazium esculentum (Retz.) SW. (Family: Athyriaceae)

Diplazium esculentum (Retz.) Sw. (Family: Athyriaceae) is one of the very popular edible ferns, a common pteridophytes usually included in one of the major ingredients in the traditional 'Ulam' (salads) preparations in Malaysia. The plant is highly valued for its several medicinal attributes. The present paper reports the physicochemical studies of the aerial parts. Diagnostic characteristics of the aerial parts powder showed presence of lignified xylem fibres and non-lignified phloem fibres, fragments of epidermal cells containing anomocytic stomata, mesophyll, palisade cells, parenchyma and collenchyma tissues, covering trichomes and prismatic crystals of calcium oxalate. Preliminary phytochemical screening of different extracts showed presence of steroids, triterpenoids, tannins and phenolic substances, flavonoids, carbohydrates, gum and mucilage. The findings of the study will provide substantial information for the proper identification of the plant drug to the future investigators.

Growth modulation effects of CBM2a under the control of AtEXP4 and CaMV35S promoters in Arabidopsis thaliana, Nicotiana tabacum and Eucalyptus camaldulensis

The expression of cell-wall-targeted Carbohydrate Binding Modules (CBMs) can alter cell wall properties and modulate growth and development in plants such as tobacco and potato. CBM2a identified in xylanase 10A from Cellulomonas fimi is of particular interest for its ability to bind crystalline cellulose. However, its potential for promoting plant growth has not been explored. In this work, we tested the ability of CBM2a to promote growth when expressed using both CaMV35S and a vascular tissue-specific promoter derived from Arabidopsis expansin4 (AtEXP4) in three plant species: Arabidopsis, Nicotiana tabacum and Eucalyptus camaldulensis. In Arabidopsis, the expression of AtEXP4pro:CBM2a showed trends for growth promoting effects including the increase of root and hypocotyl lengths and the enlargements of the vascular xylem area, fiber cells and vessel cells. However, in N. tabacum, the expression of CBM2a under the control of either CaMV35S or AtEXP4 promoter resulted in subtle changes in the plant growth, and the thickness of secondary xylem and vessel and fiber cell sizes were generally reduced in the transgenic lines with AtEXP4pro:CBM2a. In Eucalyptus, while transgenics expressing CaMV35S:CBM2a showed very subtle changes compared to wild type, those transgenics with AtEXP4pro:CBM2a showed increases in plant height, enlargement of xylem areas and xylem fiber and vessel cells. These data provide comparative effects of expressing CBM2a protein in different plant species, and this finding can be applied for plant biomass improvement.

The influence of slope on Spartium junceum root system: morphological, anatomical and biomechanical adaptation.

Root systems have a pivotal role in plant anchorage and their mechanical interactions with the soil may contribute to soil reinforcement and stabilization of slide-prone slopes. In order to understand the responses of root system to mechanical stress induced by slope, samples of Spartium junceum L., growing in slope and in plane natural conditions, were compared in their morphology, biomechanical properties and anatomical features. Soils sampled in slope and plane revealed similar characteristics, with the exception of organic matter content and penetrometer resistance, both higher in slope. Slope significantly influenced root morphology and in particular the distribution of lateral roots along the soil depth. Indeed, first-order lateral roots of plants growing on slope condition showed an asymmetric distribution between up- and down-slope. Contrarily, this asymmetric distribution was not observed in plants growing in plane. The tensile strength was higher in lateral roots growing up-slope and in plane conditions than in those growing down-slope. Anatomical investigations revealed that, while roots grown up-slope had higher area covered by xylem fibers, the ratio of xylem and phloem fibers to root diameter did not differ among the three conditions, as also, no differences were found for xylem fiber cell wall thickness. Roots growing up-slope were the main contributors to anchorage properties, which included higher strength and higher number of fibers in the xylematic tissues. Results suggested that a combination of root-specific morphological, anatomical and biomechanical traits, determines anchorage functions in slope conditions.

DROUGHT AND SALT STRESS INDUCED ANATOMICAL CHANGES IN LEAVES AND STEMS OF INDIAN BORAGE PLANTS (PLECTRANTHUS AMBOINICUS, LOUREIRO SPRENGEL)

Two pot experiments were conducted during 2014 and 2015 successive growing summer seasons to study the anatomical structure changes in leaves and stems of Indian borage plants (Plectranthus amboinicus Lour. Sprengel) due to exposure drought and salt stress. The anatomical analysis data showed that plants supplied with 65% of water holding capacity (WHC) showed considerable increase in both leaves and stems dimensions as compared to the other irrigation levels of water (45 and 25% of WHC). In addition, the highest drought stress level (25% of WHC) markedly decreased all tested parameters of both leaves and stems of Indian borage plant. As for the effect salinity on the anatomical structure of the leaf blade through the midrib region as well as lamina indicated that increasing salinity level decreased anatomical dimensions of midrib region (midrib thickness), dimensions of the midvein bundle (length, width, number of xylem vessels and average diameter of xylem vessel) and dimensions of the lamina (lamina thickness, palisade thickness and spongy tissue thickness). It was clear that the high level of salinity ECw (11.7 dSm-1) caused destroy almost the contents of vascular bundle in midrib region. The same trend was noticed on stem anatomical parameters and showed that increasing salinity level markedly reduced most of stem anatomical characters, i.e., diameter of the whole section, vascular cylinder thickness, fibers tissue thickness, phloem thickness, xylem thickness, average number of xylem vessel, average diameter of xylem vessel and pith diameter mean while thickness of cortex was increased. It was noticed that the high quantities xylem fibers in control plants was recorded and it decreased with low salinity level ECw (3.9 dSm-1), whereas, moderate and high salinity levels ECw (7.8 and 11.7 dSm-1) led to absence xylem fibers.

PtoMYB156 is involved in negative regulation of phenylpropanoid metabolism and secondary cell wall biosynthesis during wood formation in poplar

Some R2R3 MYB transcription factors have been shown to be major regulators of phenylpropanoid biosynthetic pathway and impact secondary wall formation in plants. In this study, we describe the functional characterization of PtoMYB156, encoding a R2R3-MYB transcription factor, from Populus tomentosa. Expression pattern analysis showed that PtoMYB156 is widely expressed in all tissues examined, but predominantly in leaves and developing wood cells. PtoMYB156 localized to the nucleus and acted as a transcriptional repressor. Overexpression of PtoMYB156 in poplar repressed phenylpropanoid biosynthetic genes, leading to a reduction in the amounts of total phenolic and flavonoid compounds. Transgenic plants overexpressing PtoMYB156 also displayed a dramatic decrease in secondary wall thicknesses of xylem fibers and the content of cellulose, lignin and xylose compared with wild-type plants. Transcript accumulation of secondary wall biosynthetic genes was down-regulated by PtoMYB156 overexpression. Transcriptional activation assays revealed that PtoMYB156 was able to repress the promoter activities of poplar CESA17, C4H2 and GT43B. By contrast, knockout of PtoMYB156 by CRISPR/Cas9 in poplar resulted in ectopic deposition of lignin, xylan and cellulose during secondary cell wall formation. Taken together, these results show that PtoMYB156 may repress phenylpropanoid biosynthesis and negatively regulate secondary cell wall formation in poplar.

Transcriptome analysis provides insights into wood formation during larch tree aging

Tree age affects wood formation and yield. However, the underlying mechanisms are poorly understood, particularly at the molecular level. In this study, we investigated the transcriptomic changes of the uppermost main stems of Larix kaempferi in an entire rotation period using the RNA-Seq method. In total, ∼151 million reads were obtained from the stems of 1-, 2-, 5-, 10-, 25-, and 50-year-old L. kaempferi trees. Combining these with the published Illumina sequencing reads, 299,637 assembled transcripts were generated, of which 161,232 were annotated. Time series expression profiling identified 12,927 transcripts as differentially expressed genes (DEGs); function enrichment analysis of these DEGs showed that 459 gene ontology terms in the biological process category were enriched. These terms were associated with the processes of wood formation, such as cell differentiation, growth and death, and its hormonal regulation. Based on the expression patterns of L. kaempferi homologues of genes associated with ethylene, calcium, and cell wall expansion and synthesis, the regulatory network of tracheid growth was outlined. Altogether, the comparative transcriptomic analysis reported here demonstrated the molecular aspects of aging effects on L. kaempferi wood formation. The identification of genes involved in the regulatory network of tracheid growth provides a means of investigating the regulation of wood formation in gymnosperm trees and also offers potential targets for genetic manipulation to improve the properties of xylem fibers.

Experimental investigation on Tensile property of Ricinus Communis L plant fiber to make polymer reinforced composites

Day by day demand has been increasing for light weight, high strength, high stiffed and eco-friendly composites in many engineering applications like Automobile, Aerospace, Structural etc. Natural fiber polymer composites are best suitable for making of light weight, high strength, stiffness and eco-friendly composites. Many engineers and researchers are working for the development and improvement of natural fiber reinforce polymer composites. The present work aims at introducing new natural fiber as reinforcement in polymer matrix. The method of fiber extraction is also presented. Cortex (Bark fibers) and Xylem (wood type) fiber of castor oil plant (Ricinus Communis L) are extracted. The tensile properties of single cortex fiber and single xylem fiber are tested as per the ASTM standards. The tensile strength of (323 MPa for 300 µm (0.3mm) diameter) single castor oil plant cortex fiber is comparatively very high as with the tensile strength (100 MPa for 300 µm (0.3mm) diameter) of the single castor oil plant xylem fiber. The preliminary studies of the fiber revealed that the fiber can be used as reinforcement for natural fiber composites.

Pharmacognostic Standardization of Aralia racemosa L. Stem

The present study was taken up to standardize the stem of Aralia racemosa L. for quality, purity and sample identification. Various standardization parameters like morphological, microscopical and physicochemical evaluations, preliminary phytochemical screening and fluorescence analysis of the stem of A. racemosa were done and qualitative parameters were reported. Macro and microscopic evaluation studies were performed as per the routine laboratory procedures. Phytochemical, physicochemical, florescence analysis, behaviour of powdered drug have been conducted as per the World Health Organization guidelines. Microscopy of stem revealed the presence of phellem, phellogen, phelloderm, medullary rays usually bi-serrate and powder analysis showed the presence of cork cells, lignified xylem vessels, xylem fibers and parenchyma cells. Phytochemical analysis showed the presence of saponins, flavonoids, tannins, phenols, glycosides and volatile oil. Physicochemical parameters such as moisture content, ash value, extractive value and fluorescent behaviour of stem powder were determined. These parameters are useful tools to differentiate the powdered drug material. The findings of this study will be helpful in the identificat0ion of A. racemosa stem.

Identification and expression analyses of new potential regulators of xylem development and cambium activity in cassava (Manihot esculenta).

We have identified new potential regulators of xylem cell-type determination and cellular proliferation in cassava and studied their expression in roots. Results are highly relevant for cassava biotechnology. Cassava's root system is composed of two types of root that coexist in every individual: the fibrous and the storage roots. Whether a root becomes fibrous or storage depends on the xylem cell types that it develops: fibrous roots develop xylem fibres and vessels while storage roots develop parenchyma xylem, the starch-storing tissue. A crucial question in cassava root development is how the specific xylem cell types differentiate and proliferate in the fibrous and storage roots. Using phylogenetic, protein sequence and synteny analyses we identified (1) MeVND6, MeVND7.1, MeVND7.2, MeNST3.1 and MeNST3.2 as the potential cassava orthologues of the Arabidopsis regulators of xylem cell type determination AtVND6, AtVND7 and AtNST3; and (2) MeWOX4.1 and MeWOX4.2 as the potential cassava orthologues of the Arabidopsis cambium regulator AtWOX4. Fibrous and storage roots were anatomically characterised and tested for the expression of the identified genes. Results revealed that (1) MeVND7.1 and MeVND7.2 are expressed in the fibrous but not in the storage roots; (2) MeVND6 shows low expression in both root types; (3) MeNST3.1 is not expressed in the fibrous or storage roots, while MeNST3.2 is highly expressed in both root-types and (4) MeWOX4.1 and, to a higher level, MeWOX4.2 are expressed in both the fibrous and storage roots. Results open new avenues for research in cassava root development and for food security-oriented biotechnology programmes.

Physicochemical Evaluation and Pharmacognostical Standardization of Pellionia heyneana Wedd. Leaf

Introduction: Pellionia heyneana Wedd. Leaves have long been employed as a traditional remedy by the Cholanaikan tribe of South India to treat various ailments. Methods: Pharmacological and physicochemical evaluation of P. heyneana leaf has been carried out to determine its macro and microscopic characters, and also some of its quantitative characters as per standard procedures. Results: The pharmacognostical evaluation of P. heyneana leaves revealed the presence of characteristic microscopic features of the crude drug like cystoliths in upper epidermis, helicocytic stomata in lower epidermis, large number of peculiar shaped, huge (200-400 μm) foliar sclereids, absence of palisade tissue in the lamina etc. Powder microscopy showed the presence of calcium oxalate crystals, stone cells, multicellular trichomes, resinous blocks, spiral vessels, xylem fibre, starch grains, simple fibre etc. Conclusions: All the parameters evaluated in the study will aid to identify the authenticity of P. heyneana leaf even from the crushed or powdered form.

Determining the Syringyl/Guaiacyl Lignin Ratio in the Vessel and Fiber Cell Walls of Transgenic Populus Plants

Observation of the spatial lignin distribution throughout the plant cell wall provides insight into the physicochemical characteristics of lignocellulosic biomass. The distribution of syringyl (S) and guaiacyl (G) lignin in cell walls of a genetically modified Populus deltoides and its corresponding empty vector control were analyzed with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and then mapped to determine the S/G lignin ratio of the sample surface and specific regions of interest (ROIs). The surface characterizations of transgenic cross-sections within 1 cm vertical distance of each other on the stem possess similar S/G lignin ratios. The analysis of the ROIs determined that there was a 50% decrease in the S/G lignin ratio of the transgenic xylem fiber cell walls.

PERBEDAAN STRUKTUR XILEM BATANG SENGON (Falcataria moluccana) DARI PROVENAN SOLOMON DAN WAMENA

Sengon (Falcataria moluccana) is fast growing species mostly planted by farmers due to its high productivity. Sengon originating from Solomon Island has been known with the high productivity eventhough susceptible to gall rust attack; on the other hand, sengon originating from Wamena is known to be more tolerant to gall rust attack. There is no previous study in terms of stem xylem structures comparing sengon from those seed origins. Therefore, this study was undertaken to identify the differences in anatomical structure of sengon stem; and to compare the xylem cell based on proportions and dimensions of the stems between the two provenances. Six stem samples of tolerant Wamena provenance and six samples of susceptible Solomon provenance were used in this study. Samples were collected from progeny trial of sengon in Lumajang, Jawa Timur. The observations include the anatomical structures and vessel element, parenchyma apotracheal cell, parenchyma paratracheal cell, xylem fiber, fiber length, and fiber diameter. The result showed that there was no difference in terms of anatomical structures between sengon Wamena (tolerant) and Solomon (susceptible) stem in cross section, tangential and radial section of periderm, phloem, secondary xylem (vessel cell, xylem fiber, and parenchyma xylem) and pith. However, in one of susceptible stem sample, a black reaction zone on the secondary xylem was found. Analysis of variance showed that parenchyma paratracheal cell, apotracheal cell, number of xylem fibers, xylem fiber diameter and length were not significantly different between stem of sengon Wamena (tolerant) and Solomon (susceptible).

The anatomical features of the desert halophytes Zygophyllum album L.F. and Nitraria retusa (Forssk.) Asch

The morpho-anatomical features of Zygophyllum album L.F. and Nitraria retusa growing on the El sokhna region, adjacent western coast of Red sea, Egypt, which contribute for their adaptation to the stressful habitat conditions were studied. An analysis of the morphological and anatomical characters of their leaves, stems and roots revealed representative of the halo-xerophilic characters among these plants. Adaptation is achieved by succulence, the presence of trichomes, sunken stomata, cylindrical leaves, laminate unifacial leaves, xylem fibers, sclerenchyma tissue, storage materials and crystals. The above mentioned morpho-anatomical features in response to the stressful conditions could be considered as anatomical function to adaptation to drought, salinity and heat stress.

Lignin Deposition in Cotton Cells ? Where is the lignin?

and poplar have been investigated, detailed examination of lignin deposition in agriculturally important crops such as cotton has been very limited. Lignin is a complex polymeric structure of phenolic compounds containing monolignols (coniferyl alcohol (guaiacyl, G-lignin monomer), sinapyl alcohol (sinapyl, S-lignin monomer), p-coumaryl alcohol (hydroxyphenyl, H-lignin monomer) and 5-OH coniferyl alcohol (5-hydroxyguaiacyl, 5-OH G-lignin monomer)) [1]. The key genes involved in lignin biosynthesis have been identified and functionally characterized in model plants allowing the realisation of lignin manipulation for potential useful application in plants (reviewed by Bedon and Legay) [2]. The lignin monomers are generally associated with the plant secondary cell wall (SCW) typified by specialised cells such as xylem vessels, xylem fibres in angiosperms, and tracheids in gymnosperms. The SCWs in these cells function to allow water transport via xylem vessels and tracheids, to provide mechanical support via tracheids, xylem fibres and phloem fibres, and to protect against biotic attack and abiotic stresses. The physical properties of lignin that contribute to its roles in different cell types is highly dependent on its quantity and quality, the latter determined by the ratio of the monolignols and how they are covalently linked. Cotton

Trait selection to improve windfirmness in trees.

Abstract Windfirmness of trees, the ability to withstand strong winds without incurring internal damage to xylem (fibre buckling in timber) or structural failure due to stem snap (wind snap) or over turning of root plates (wind throw), is a complex phenomenon that results from the interaction of multiple traits. Selective tree breeding has the potential to improve windfirmness, but to date there have been few examples where this has been attempted. A key difficulty is that windfirmness is not simply associated with a single trait that can be selected for, but instead requires a comprehensive understanding of tree biomechanics and the different developmental responses to wind. This review summarizes the elastic and plastic responses in trees due to wind to assist in the identification of those traits associated with windfirmness in growth allometry, wood properties and root growth. It addresses recent attempts to begin the selection process to improve the windfirmness of forests and plantations in light of changing wind regimes around the world. Finally, it discusses the unintended consequences that could occur from selective breeding for windfirmness, which could potentially compromise tree growth and yield as well as wood quality.

TBL3 and TBL31, Two Arabidopsis DUF231 Domain Proteins, are Required for 3-O-Monoacetylation of Xylan.

Xylan, a major constituent of secondary cell walls, is made of a linear chain of β-1,4-linked xylosyl residues that are often substituted with glucuronic acid/methylglucuronic acid side chains and acetylated at O-2 and O-3. Previous studies have shown that ESK1, an Arabidopsis DUF231 protein, is an acetyltransferase catalyzing 2-O- and 3-O-monoacetylation of xylan. However, the esk1 mutation only causes a partial loss of xylan 2-O- and 3-O-monoacetylation, suggesting that additional xylan acetyltransferase activities are involved. In this report, we demonstrated the essential roles of two other Arabidopsis DUF231 genes, TBL3 and TBL31, in xylan acetylation. The expression of both TBL3 and TBL31 was shown to be induced by overexpression of the secondary wall master transcriptional regulator SND1 (secondary wall-associated NAC domain protein1) and down-regulated by simultaneous mutations of SND1 and its paralog NST1, indicating their involvement in secondary wall biosynthesis. β-Glucurondase (GUS) reporter gene analysis showed that TBL3 and TBL31 were specifically expressed in the xylem and interfascicular fibers in stems and the secondary xylem in root hypocotyls. Expression of fluorescent protein-tagged TBL3 and TBL31 in protoplasts revealed their localization in the Golgi, where xylan biosynthesis occurs. Although mutation of either TBL3 or TBL31 alone did not cause any apparent alterations in cell wall composition, their simultaneous mutations were found to result in a reduction in xylan acetylation. Further structural analysis demonstrated that the tbl3 tbl31 double mutant had a specific reduction in 3-O-acetylation of xylan. In addition, the tbl3 tbl31 esk1 triple mutant displayed a much more drastic decrease in 3-O-acetylation of xylan, indicating their functional redundancy in xylan 3-O-acetylation. These findings indicate that TBL3 and TBL31 are secondary wall-associated DUF231 genes specifically involved in xylan 3-O-acetylation.

The tomato plastidic fructokinase SlFRK3 plays a role in xylem development.

Plants have two kinds of fructokinases (FRKs) that catalyze the key step of fructose phosphorylation, cytosolic and plastidic. The major cytosolic tomato FRK, SlFRK2, is essential for the development of xylem vessels. In order to study the role of SlFRK3, which encodes the only plastidic FRK, we generated transgenic tomato (Solanum lycopersicon) plants with RNAi suppression of SlFRK3 as well as plants expressing beta-glucoronidase (GUS) under the SlFRK3 promoter. GUS staining indicated SlFRK3 expression in vascular tissues of the leaves and stems, including cambium, differentiating xylem, young xylem fibers and phloem companion cells. Suppression of SlFRK3 reduced the stem xylem area, stem and root water conductance, and whole-plant transpiration, with minor effects on plant development. However, suppression of SlFRK3 accompanied by partial suppression of SlFRK2 induced significant growth-inhibition effects, including the wilting of mature leaves. Grafting experiments revealed that these growth effects are imposed primarily by the leaves, whose petioles had unlignified, thin-walled xylem fibers with collapsed parenchyma cells around the vessels. A cross between the SlFRK2-antisense and SlFRK3-RNAi lines exhibited similar wilting and anatomical effects, confirming that these effects are the result of the combined suppression of SlFRK3 and SlFRK2. These results demonstrate a role of the plastidic SlFRK3 in xylem development and hydraulic conductance.

Overexpression of ARBORKNOX1 delays the differentiation of induced somatic sector analysis (ISSA) derived xylem fibre cells in poplar stems

ARBORKNOX1 (ARK1), a poplar functional homolog of the Arabidopsis Class-I KNOTTED- like homeobox (KNOXI) transcription factor SHOOT MERISTEMLESS (STM), has been shown to have a role in maintaining meristematic cells in an undifferentiated state. Studies in which this gene was ectopically overexpressed identified a delay in the differentiation of cambial derivatives. Overexpression of ARK1 in poplar stem sectors, using the induced somatic sector analysis (ISSA) experimental system, was undertaken to further investigate its role in the differentiation of xylem fibre cells. ISSA involves the in vivo transformation of a small number of cambial cells in the stem with a gene of interest giving rise to a discreet transgenic tissue sector that can be directly compared to adjacent non-transgenic fibres to elucidate gene function. Phenotypes obtained were comparable with the proposed role of ARK1, where a delay in the development of the cell wall in differentiating fibre cells of active cambia was observed. Additional evidence suggests a role for ARK1 in the positive regulation of cell viability in the cambium. The significance of dormancy signals in the context of differentiation was also highlighted, as some transgenic fibres failed to fully differentiate prior to the onset of dormancy. Our findings are discussed in the context of wood formation and the use of ISSA as an experimental system.

Deciphering the Niches of Colonisation of Vitis vinifera L. by the Esca-Associated Fungus Phaeoacremonium aleophilum Using a gfp Marked Strain and Cutting Systems.

IntroductionEsca disease has become a major threat for viticulture. Phaeoacremonium aleophilum is considered a pioneer of the esca complex pathosystem, but its colonisation behaviour inside plants remains poorly investigated.Material and MethodsIn this study, P. aleophilum::gfp7 colonisation was assessed six and twelve weeks post-inoculation in two different types of tissues: in the node and the internode of one year-old rooted cuttings of Cabernet Sauvignon. These processes of colonisation were compared with the colonisation by the wild-type strain using a non-specific lectin probe Alexa Fluor 488-WGA.ResultsData showed that six weeks post-inoculation of the internode, the fungus had colonised the inoculation point, the bark and xylem fibres. Bark, pith and xylem fibres were strongly colonised by the fungus twelve weeks post-inoculation and it can progress up to 8 mm from the point of inoculation using pith, bark and fibres. P. aleophilum was additionally detected in the lumen of xylem vessels in which tyloses blocked its progression. Different plant responses in specific tissues were additionally visualised. Inoculation of nodes led to restricted colonisation of P. aleophilum and this colonisation was associated with a plant response six weeks post-inoculation. The fungus was however detected in xylem vessels, bark and inside the pith twelve weeks post-inoculation.ConclusionsThese results demonstrate that P. aleophilum colonisation can vary according to the type of tissues and the type of spread using pith, bark and fibres. Woody tissues can respond to the injury and to the presence of this fungus, and xylem fibres play a key role in the early colonisation of the internode by P. aleophilum before the fungus can colonise xylem vessels.