During gel (gum) formation in angiosperm trees, fibrillar material accumulated protective layers of xylem parenchyma cells before being secreted across half-bordered pit membranes into vessel elements. Immunogold labeling demonstrated that this was mainly composed partially esterified pectic polysaccharides. The primary wall expanding tyloses, an extension the layer, similar substances to completely block In most studies, these occluding structures were reported be formed response causative...

Summary Accurate wood identification is crucial for combatting the illegal logging and trade of forest products worldwide. However, certain challenges such as small specimen size, high density, level degradation can complicate process. There therefore a need to develop methods use complementary techniques in forensic identification, particularly difficult samples. This study utilized confocal laser scanning microscopy (CLSM) detect locate autofluorescence axial parenchyma cells (APCs)...

ABSTRACT Aluminum and bisulfite salts inhibit the growth of several fungi bacteria, their application effectively controls potato soft rot caused by Erwinia carotovora . In an effort to understand inhibitory action, ultrastructural changes in subsp. atroseptica after exposure (0 20 min) different concentrations (0.05, 0.1, 0.2 M) these were examined using transmission electron microscopy. Plasma membrane integrity was evaluated SYTOX Green fluorochrome that penetrates only cells with altered...

Barrier zone formation was studied in small branches of Ulmus americana L., Prunus pensylvanica L.f., and Populus balsamifera L. following inoculation with Ophiostoma ulmi (Buism.) Nannf. (the Dutch elm disease pathogen). zones were continuous the nonhosts whereas they generally discontinuous U. americana; barrier also occurred at a later stage infection latter than former. formed parenchyma cells fibers americana, mainly pensylvanica, balsamifera. Fibers as principal component are described...

The host–pathogen interaction leading to Dutch elm disease was analyzed using histo- and cyto-chemical tests in an vitro system. Friable hard susceptible Ulmus americana callus cultures were inoculated with the highly aggressive pathogen Ophiostoma novo-ulmi. Inoculated tissues compared water-treated studied light microscopy (LM), transmission-electron (TEM), scanning-electron (SEM). New aspects of this are described. These include histological observation, for first time plant cultures,...

An ultrastructural and cytochemical investigation of the development Rigidoporus lignosus , a white-rot fungus inoculated into wood blocks, was carried out to gain better insight structure role extracellular sheaths produced by this during degradation. Fungal had dense or loose fibrillar appearance were differentiated from fungal cell wall early after inoculation. Close association between fibrils walls observed at both advanced stages alteration. often seen deep in host walls, sometimes...

Ophiostoma ulmi (the Dutch elm disease pathogen) was inoculated into 13 nonhost tree and shrub species. Four classes were recognized based on their susceptibility to this pathogen. In Prunus pensylvanica (class I), bubbles formed in vessel members within 3 days after inoculation, gels 5 later. At day 5, the vascular cambium covering colonized zone became altered. A barrier 60% of twigs. When twigs wilted, vessels around twig occluded, formation partial. Populus balsamifera II), tyloses...

This report presents a survey of previous and more recent ultrastructural cytochemical investigations disease development in elm, caused by Ophiostoma novo-ulmi, with results some comparative studies other wilt diseases f.spp., Fusarium oxysporum Verticillium sp. For studies, probes complexed to colloidal gold detect cellulose, pectin, chitin, DNA were used. Thus, the formation tyloses, pit membrane alterations, effect on parenchyma cells mature as well young tissue characterized. Vessel...

Aluminum chloride (AlCl(3)) and sodium metabisulfite (Na(2)S(2)O(5)) have received increasing attention as antifungal agents for the control of plant diseases. In an effort to understand their toxic action on fungi, ultrastructural changes membrane damage in Fusarium sambucinum (Ascomycota) Heterobasidion annosum (Basidiomycota) response salt exposure was investigated using transmission electron microscopy. Conidial quantified SYTOX Green stain, which only enters altered membranes. The...

ABSTRACT A histological study was conducted to provide insights into the defense mechanisms of Pinus banksiana resistant European (EU) race Gremmeniella abietina in naturally infected sites. At time sampling, only apparent symptom a blight induced at tip shoots. The identity G. during microscopic examinations confirmed by an immunogold labeling method. Once fungus had succeeded penetrating bracts through stomata, it invaded stem cortex and phloem cells attained vascular cambium. progression...

To better characterize the host–pathogen interaction leading to Dutch elm disease, pathogenicity tests were carried out under controlled conditions. Putative resistant hybrid clones 2213 and 2245 from same Ulmus parvifolia Jacq. × americana L. cross putative U. clone 503, as well saplings of grown seeds, inoculated with strains Ophiostoma ulmi (Buism.) Nannf. or novo-ulmi Brasier, including H327 AST27, which carry different alleles at Pat1 locus display levels aggressiveness. The occurrence...

The colonization processes of the xylem in susceptible carnation cv. Early Sam and resistant Novada were studied ultrastructurally following inoculation with Fusarium oxysporum f.sp. dianthi. Samples from 1 to 3 cm above incision collected over 5 weeks processed conventional procedures as well probes for cellulose, N-acetyl-glucosamine, pectin. fungus grew profusely vessel lumina cultivar. Some colonized vessels lined coating material connected fungal cell wall extending into host through...

An ultrastructural and cytochemical investigation of the development Phellinus noxius, a white-rot fungus, in wood chips Betula papyrifera was done to gain insight into cellular mechanisms cell wall degradation. Extracellular sheaths microhyphae were seen be involved colonization. Close association observed between these fungal structures walls at both early advanced stages alteration. Fungal often deep inside host walls, sometimes enclosing residual fragments. Investigations using gold...

Ophiognomonia clavigignenti-juglandacearum endangers the survival of butternut (Juglans cinerea) throughout its native range. While screening for disease resistance, we found that artificial inoculations 48 seedlings with O. induced expression external symptoms, but only after a period dormancy. Before dormancy, compartmentalized tissues such as necrophylactic periderms (NPs) and xylem reaction zones (RZs) contributed to limiting pathogen invasion. Phenols were regularly detected in RZs,...

Barrier zone formation was studied in annual shoots and small branches of Ulmus americana L., Prunus pensylvanica L.f., Populus balsamifera L. following inoculation with Ophiostoma ulmi (Buism.) Nannf. Ultrastructural observations showed that electron-opaque compounds, which usually were identified as containing phenolics by previous histochemical tests, often present within cells this tissue. Many lipidic globules also observed some barrier balsamifera. Additional wall layers, suberized or...

The intercellular ascomycetous pathogen Cymadothea trifolii, causing sooty blotch of clover, proliferates within leaves Trifolium spp. and produces a complex structure called interaction apparatus (IA) in its own hyphae. Opposite the IA plant plasmalemma invaginates to form bubble. Both structures are connected by tube with an electron-dense sheath. Using immunocytochemistry on high-pressure frozen freeze-substituted samples, we examined several fungal cell wall components, including those...

In eastern Canada, the white pine weevil (Pissodes strobi Peck) is a pest of several native and spruce species introduced species, Norway (Picea abies Karst). We evaluated feeding activities, oviposition rate adult emergence on field-grown subjected to jasmonic acid or wounding pretreatments. also monitored host–plant reaction attack, treatments by quantifying mono- sesquiterpenes in bark characterizing some molecular aspects terpenoid response. Two cDNA sequences were identified that had...

In vitro effects of the antimicrobial synthetic D2A21 peptide on structure spores four fungal pathogens causing important tree diseases were examined by microscopy in parallel with tests to measure inhibition spore germination. With light microscopy, use SYTOX ® green stain indicated that rapidly altered plasma membrane conidia three Ascomycetes: Gremmeniella abietina (Lagerberg) Morelet var. Petrini et al., Ophiostoma ulmi (Buism.) Nannf., and Nectria galligena Bres. basidiospores...

Summary Here, cell and wall modifications in resistant (cv. I ) susceptible II carnation inoculated with Fusarium oxysporum are characterized. Samples, of various days after inoculation (dai), were double‐fixed gold‐complexed probes used for cellulose, pectin, chitin. In cv. , mature paratracheal cells contained appositions mostly bound by a cellulose layer over the densely opaque native walls. Middle lamellae younger cells, many hyperplastic much distorted, obliterated, displayed mingling...