Histological evidence of resistance to Endocronartium harknessii in Pinus contorta var. latifolia

1990 ◽  
Vol 68 (8) ◽  
pp. 1728-1737 ◽  
Author(s):  
E. A. Allen ◽  
P. V. Blenis ◽  
Y. Hiratsuka
Keyword(s):  
Pinus Contorta ◽  
Secondary Xylem ◽  
Rust Fungus ◽  
Cortical Lesions ◽  
Gall Formation ◽  
Cortical Cells ◽  
Endocronartium Harknessii ◽  
Infected Cells ◽  
Initial Resistance ◽  
Resistance To Infection

Resistance to the western gall rust fungus, Endocronartium harknessii, was observed in 3-, 10-, 20-, and 33-month-old greenhouse-grown seedlings of lodgepole pine (Pinus contorta var. latifolia). Three sites of resistance were identified: epidermal, cortical, and cambial. In cases of epidermal resistance, penetration of the epidermis occurred, but infection was prevented by an apparent hypersensitive response. Cortical resistance occurred where infected cells in the cortex were successfully isolated by necrophylactic periderm and the infected tissue was exfoliated with the rhytidome. In cambial resistance, infections progressed to the vascular cambium where infected cells and cambial initials were inactivated. This resulted in abnormal secondary xylem development, characterized by a zone of pathological tissue extending from the pith to the epidermis. In a number of infected seedlings, cambial function was restored and infected lesions were overgrown. Live mycelium was often maintained in cortical lesions and in some cases reinvaded healthy cortical cells. These latent-type infections resulted in the initiation of gall formation up to 1 year after initial resistance to infection occurred. Key words: tree improvement, western gall rust, pine stem rust.

Early symptom development in lodgepole pine seedlings infected with Endocronartium harknessii

1990 ◽  
Vol 68 (2) ◽  
pp. 270-277 ◽  
Author(s):  
Eric A. Allen ◽  
P. V. Blenis ◽  
Y. Hiratsuka
Keyword(s):  
Pinus Contorta ◽  
Rust Fungus ◽  
Infected Tissue ◽  
Cortical Cells ◽  
Subsequent Formation ◽  
Early Symptom ◽  
Pine Seedlings ◽  
Endocronartium Harknessii ◽  
Periderm Formation ◽  
Lignin Deposition

Six-week-old Pinus contorta seedlings were inoculated with spores of the western gall rust fungus Endocronartium harknessii. Of 660 seedlings inoculated, 174 showed early symptoms and were sampled for histological observation in the 7 weeks following inoculation. Pigmentation of epidermal cells was the first externally visible response to infection, generally occurring 14–28 days after inoculation. Developing symptoms were extremely variable, ranging from little or no visible response to severe necrosis. The appearance of external symptoms was largely due to changes occurring in underlying infected cortical cells such as the production of phenolic compounds, necrophylactic periderm, or necrotic tissue. Intercellular lignin deposition was observed in infected tissue and was thought to be associated with necrophylactic periderm formation. Suppression of normal exophylactic periderm development was evident in virtually all infected tissue zones. Infection of the vascular cambium occurred as early as 21 days after inoculation and resulted in the subsequent formation of distorted xylem tracheids typical of gall tissue.

Early symptoms and resistance of lodgepole pine seedlings inoculated with western gall rust

1992 ◽  
Vol 70 (6) ◽  
pp. 1274-1278 ◽  
Author(s):  
H. O. Kojwang ◽  
B. J. van der Kamp
Keyword(s):  
Pinus Contorta ◽  
Rust Fungus ◽  
Good Prediction ◽  
Gall Formation ◽  
Inoculum Concentration ◽  
Early Symptoms ◽  
Pine Seedlings ◽  
Endocronartium Harknessii ◽  
One Year ◽  
Two Stages

One-year-old seedlings in 10 open-pollinated Pinus contorta families were inoculated with spores of the rust fungus Endocronartium harknessii at two stages of seedling maturity and two levels of inoculum concentration. The early symptoms (general red stain, red flecks, red streaks) that appeared on the seedlings were recorded 2, 4, and 8 weeks after inoculation, while the number of galls was recorded 1 year after inoculation. The frequency of general red stain and red flecks varied significantly among families. Resistance of families as percent of seedlings producing galls also varied significantly. The frequency of early symptoms was only poorly correlated with family resistance. Also, the occurrence of early symptoms on individual seedlings did not give a good prediction of gall formation on them. These results suggest that early symptoms cannot accurately identify resistant families or individuals. Key words: Endocronartium harknessii, Pinus contorta, symptoms, resistance.

Resistant responses in juvenile seedlings of Pinus densiflora (Japanese red pine) inoculated with Endocronartium harknessii

1989 ◽  
Vol 67 (12) ◽  
pp. 3545-3552 ◽  
Author(s):  
A. A. Hopkin ◽  
P. V. Blenis ◽  
Y. Hiratsuka
Keyword(s):  
Host Cell ◽  
Vascular Tissue ◽  
Pinus Densiflora ◽  
Light And Electron Microscopy ◽  
Host Cells ◽  
Cortical Cells ◽  
Host Cell Death ◽  
Endocronartium Harknessii ◽  
Infected Cells ◽  
Endodermal Cells

Hypocotyls of Pinus densiflora, a species known to be resistant to western gall rust, were inoculated with Endocronartium harknessii and examined by light and electron microscopy. Host cells, when initially infected, were apparently unaffected, as were the haustoria within them. Seedlings were observed to respond to infection in two ways. In the first type of response, infected cells showed signs of necrosis by 9 days after inoculation, although infecting haustoria appeared normal. By 18 days, most cortical cells in the centre of the infected region were necrotic, as were the haustoria within them. Infected cells at the colony margin still appeared healthy, indicating that host cell necrosis lagged behind infection and only occurred after the haustorium was established. Four weeks after inoculation, a ring of suberized and lignified endodermal cells separated the infected cortex from the uninfected vascular tissue and appeared to prevent further inward growth of the fungus. The second response type involved production of encapsulations around haustoria. Encapsulations appeared to have formed after haustoria senescence and were eventually followed by host cell death.

Susceptibility of Pinus contorta - Pinus banksiana complex to Endocronartium harknessii: host-pathogen interactions

1999 ◽  
Vol 77 (7) ◽  
pp. 1035-1043 ◽  
Author(s):  
Rong-Cai Yang ◽  
Zhihong Ye ◽  
Yasu Hiratsuka
Keyword(s):  
Pinus Banksiana ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Rust Fungus ◽  
Jack Pine ◽  
Natural Hybridization ◽  
Host Group ◽  
Group Interactions ◽  
Endocronartium Harknessii ◽  
Rust Susceptibility

Lodgepole (Pinus contorta Dougl. ex Lound.) and jack (Pinus banksiana Lamb.) pines occur sympatrically and hybridize in central and northwestern Alberta, providing opportunities for studying unique ecological and evolutionary interactions. We conducted a greenhouse inoculation experiment to investigate interactions between 40 populations of lodgepole and jack pines and their putative hybrids across this hybrid zone and two sources of the western gall rust fungus, Endocronartium harknessii (J.P. Moore) Y. Hiratsuka, one from lodgepole pine and the other from jack pine. Rust susceptibility and height were assessed when the seedlings were 6 months and 1 year old. Lodgepole pine and the hybrids were significantly more susceptible to the rust infection than jack pine. Jack pine grew significantly faster than the hybrids and lodgepole pine. In addition, the seedlings infected with spores from lodgepole pine grew significantly slower than those with spores from jack pine. While the overall rust scores indicated that spores from lodgepole pine was more virulent to the hosts than those from jack pine, both spore sources were better adapted to their own host species, causing significant spore source × host group interactions. However, such host specificity in the western gall rust is far from stabilized (equilibrium) because of continued gene exchanges among the two parental species and their hybrids.Key words: Pinus contorta - Pinus banksiana complex, western gall rust, natural hybridization, coevolutionary genetics.

Random amplified polymorphic DNA variability among geographic isolates of western gall rust fungus in Canada

2001 ◽  
Vol 31 (8) ◽  
pp. 1304-1311 ◽  
Author(s):  
Changxi Li ◽  
Francis C Yeh ◽  
Yasu Hiratsuka
Keyword(s):  
Pinus Banksiana ◽  
Pinus Contorta ◽  
Lodgepole Pine ◽  
Random Amplified Polymorphic Dna ◽  
Rust Fungus ◽  
Jack Pine ◽  
Fungal Isolates ◽  
Rapd Pattern ◽  
Endocronartium Harknessii ◽  
East West

Geographic variability among western gall rust (WGR) fungus (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka) was studied by random amplified polymorphic DNA (RAPD). Samples were taken from lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) host at four locations in British Columbia and Alberta and from jack pine (Pinus banksiana Lamb.) host at nine locations in Alberta, Saskatchewan, Manitoba, and Ontario. Of 90 random oligonucleotide primers screened, 9 were chosen for analysis. These nine primers consistently amplified 41 sharp and reproducible RAPDs (fragments) of the WGR fungal isolates over several independent runs. Eighteen of the 41 RAPDs were polymorphic (showing the presence of both marker and null phenotypes), of which 15 could discriminate WGR isolates of lodgepole pine hosts from jack pine ones. Of these 15 RAPDs, five were unique to isolates of lodgepole and five to jack pine. The remaining five RAPDs were significantly heterogeneous in the RAPD frequency between WGR isolates of the two host origins. The RAPD pattern of WGR isolates from lodgepole pine was uniform. However, isolates from jack pine differed significantly in the frequency of four RAPDs among locations, with an east-west trend of decreasing similarity in RAPD. Analysis of molecular variance apportioned 76.3, 14.4, and 9.3% of the total RAPD variability to differences among hosts, to differences among locations within hosts, and to differences within locations, respectively. The large differentiation between WGR fungal isolates sampled in lodgepole pine and jack pine hosts might suggest that selective pressure for host specificity in sampled populations was strong.

REACTION TISSUES IN GNETUM GNEMON A PRELIMINARY REPORT

IAWA Journal ◽  
2001 ◽  
Vol 22 (4) ◽  
pp. 401-413 ◽  
Author(s):  
P. B. Tomlinson
Keyword(s):  
Cell Walls ◽  
Tension Wood ◽  
Secondary Xylem ◽  
Secondary Phloem ◽  
Outer Cortex ◽  
Cortical Cells ◽  
Wood Fibres ◽  
Developmental Feature ◽  
Gnetum Gnemon ◽  
Clear Differentiation

Gnetum gnemon exhibits Rouxʼs model of tree architecture, with clear differentiation of orthotropic from plagiotropic axes. All axes have similar anatomy and react to displacement in the same way. Secondary xylem of displaced stems shows little eccentricity of development and no reaction anatomy. In contrast, there is considerable eccentricity in extra-xylary tissue involving both primary and secondary production of apparent tension-wood fibres (gelatinous fibres) of three main kinds. Narrow primary fibres occur concentrically in all axes in the outer cortex as a normal developmental feature. In displaced axes gelatinous fibres are developed abundantly and eccentrically on the topographically upper side, from pre-existing and previously undetermined primary cortical cells. They are wide with lamellate cell walls. In addition narrow secondary phloem fibres are also differentiated abundantly and eccentrically on the upper side of displaced axes. These gelatinous fibres are narrow and without obviously lamellate cell walls. Eccentric gelatinous fibres thus occupy a position that suggests they have the function of tension wood fibres as found in angiosperms. This may be the first report in a gymnosperm of fibres with tension capability. Gnetum gne-mon thus exhibits reaction tissues of unique types, which are neither gymnospermous nor angiospermous. Reaction tissues seem important in maintaining the distinctive architecture of the tree.

Ontogenèse des nodules caulinaires du Sesbania rostrata (légumineuses)

1984 ◽  
Vol 62 (5) ◽  
pp. 982-994 ◽  
Author(s):  
E. Duhoux
Keyword(s):  
Sesbania Rostrata ◽  
Cortical Cells ◽  
Root Cortex ◽  
Central Mass ◽  
Intracellular Release ◽  
Infection Threads ◽  
Bacterial Penetration ◽  
Infected Cells ◽  
Determinate Growth

Stem nodules of the legume Sesbania rostrata are ovoids, contain chlorophyll and have determinate growth. They possess a large central mass of infected cells. Stem mamillae are regularly arranged in vertical files along the stem and develop into nodules when they are infected by a specific Rhizobium. Each nodule arises from the development of an infected region of the incipient root cortex. The infection in S. rostrata has been shown to proceed in four sequential stages. Some of them have never been shown to occur in other legumes: (i) bacterial penetration takes place in degenerated (dead) cortical cells; (ii) proliferation of the bacteria occurs in the intercellular cavities and initiates a meristematic nodule; (iii) protusion of infection threads at first occurs intercellularly and then intracellularly from the cavities; (iv) finally there is an intracellular release of Rhizobia by an endocytotic process.

Anatomy and ultrastructure of a Rhododendron root–fungus association

1980 ◽  
Vol 58 (23) ◽  
pp. 2421-2433 ◽  
Author(s):  
T. A. Peterson ◽  
W. C. Mueller ◽  
L. Englander
Keyword(s):  
Fungal Infection ◽  
Secondary Growth ◽  
Cortical Layer ◽  
Electron Microscopic ◽  
Cortical Cells ◽  
Host Cytoplasm ◽  
Hair Roots ◽  
Short Period ◽  
Infected Cells ◽  
Hyphal Coils

Light and electron microscopic investigations of the roots of Rhododendron and other ericaceous plants growing in the vicinity of Clavaria fruiting structures showed a fungal infection consistently associated with the epidermal and cortical cells of the "hair roots." Uninfected hair roots consisted of an epidermis and a one cell thick cortical layer surrounding the stele. Secondary growth in the stele and formation of a cork layer by division of the pericycle caused the cortex and epidermis to slough as the root matured. The structure of the infected hair roots was similar except for the presence of fungus in epidermal and cortical cells. As judged by the appearance of septa, at least two fungi were involved, one with dolipore septa that formed hyphal coils in the infected cells, and one with septa associated with Woronin bodies that occurred as single hyphal strands. Hyphae were found penetrating the cells from the exterior of the root and also passing from cell to cell. No correlation between fungal infection and the phenolic content of the cells could be made. Dissolution of both the fungal and host cytoplasm appeared to occur as the cells were sloughed. It appears that the fungus–root relationship is complex and is limited in duration to a short period of time during the development of the hair roots.

Lodgepole pine provenances differ in chemical defense capacities against foliage and stem diseases

2010 ◽  
Vol 40 (12) ◽  
pp. 2333-2344 ◽  
Author(s):  
Christopher M. Wallis ◽  
Richard W. Reich ◽  
Kathy J. Lewis ◽  
Dezene P.W. Huber
Keyword(s):  
Secondary Metabolites ◽  
Pinus Contorta ◽  
Dominant Species ◽  
Lodgepole Pine ◽  
Quantitative Resistance ◽  
Foliar Diseases ◽  
Seed Sources ◽  
Endocronartium Harknessii ◽  
Foliar Concentrations ◽  
Foliar Pathogens

Maximization of lodgepole pine ( Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson) growth in a future climate with increased pest activity requires an understanding of the natural variability of quantitative resistance to disease. Foliar and bark secondary metabolites from different lodgepole pine provenances (populations) were quantified and correlated with severity of foliar diseases caused by Lophodermella spp. ( Lophodermella concolor (Dearn.) Darker or Lophodermella montivaga Petre.) or Elytroderma deformans (Wier) Darker and bark diseases caused by Elytroderma or Endocronartium harknessii (J.P. Moore) Y. Hiratsuka. Greater foliar concentrations of lignin, tannins, and some phenolics were associated with increased resistance to single or multiple foliar pathogens. Bark secondary metabolites levels were generally unassociated with resistance to bark diseases. Provenances appearing to originate in ecosystems where lodgepole pine are not the dominant species generally were more susceptible to foliar diseases and had less foliar defense-associated compounds than trees from areas where pines were the dominant species, yet clear trends proved to be elusive. Regardless, pine provenances with greater foliar levels of identified defense-associated compounds should be preferred seed sources for replanting forests in areas in which foliar disease is expected to be increasingly prevalent.

scholarly journals Nodulation of Aeschynomene afraspera and A. indica by Photosynthetic Bradyrhizobium Sp. Strain ORS285: The Nod-Dependent Versus the Nod-Independent Symbiotic Interaction

2011 ◽  
Vol 24 (11) ◽  
pp. 1359-1371 ◽  
Author(s):  
Katia Bonaldi ◽  
Daniel Gargani ◽  
Yves Prin ◽  
Joel Fardoux ◽  
Djamel Gully ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Lateral Roots ◽  
Root Hairs ◽  
Infection Process ◽  
Cortical Cells ◽  
Symbiotic Interaction ◽  
Root Cortex ◽  
Bradyrhizobium Sp ◽  
Infected Cells ◽  
Green Fluorescent

Here, we present a comparative analysis of the nodulation processes of Aeschynomene afraspera and A. indica that differ in their requirement for Nod factors (NF) to initiate symbiosis with photosynthetic bradyrhizobia. The infection process and nodule organogenesis was examined using the green fluorescent protein–labeled Bradyrhizobium sp. strain ORS285 able to nodulate both species. In A. indica, when the NF-independent strategy is used, bacteria penetrated the root intercellularly between axillary root hairs and invaded the subepidermal cortical cells by invagination of the host cell wall. Whereas the first infected cortical cells collapsed, the infected ones immediately beneath kept their integrity and divided repeatedly to form the nodule. In A. afraspera, when the NF-dependent strategy is used, bacteria entered the plant through epidermal fissures generated by the emergence of lateral roots and spread deeper intercellularly in the root cortex, infecting some cortical cells during their progression. Whereas the infected cells of the lower cortical layers divided rapidly to form the nodule, the infected cells of the upper layers gave rise to an outgrowth in which the bacteria remained enclosed in large tubular structures. Together, two distinct modes of infection and nodule organogenesis coexist in Aeschynomene legumes, each displaying original features.

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