Defense Mechanisms in Leaves and Fruit of Trees to Fungal Infection

Adaskaveg, J. E.

doi:10.1007/978-3-662-01642-8_11

Cited by 8 publications

(7 citation statements)

References 126 publications

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“…a, anamorph(s); b, ascus; c, ascospore; d, edpidermis or cell(s); e, endodermis or cell(s); f, hymenial layer; g, gelatenous sheath; h, hypha(e); i, stroma; j, hypodermis or cell(s); k, stromatal bending of tissue; m, collapsed mesophyll cell(s); n, noncollapsed mesophyll cell(s); r, resin duct/cells; s, stationary interface material; t, teleomorph(s); v, vascular/transfusion tissue; u, dead tissue; x, green (living) tissue 34 F. F. Jewell, Sr was observed as much as 180 mm into the normal appearing tissue. Similar observations of an interface have been reported for other needle-cast fungi (WILLIAMSON et al 1976;MITCHELL et al 1978;JEWELL 1990aJEWELL , b, 1993aJEWELL , 1994ADASKAVEG 1992). A sharp demarcation of dead and green tissue (living) was evident ( Fig.…”

Section: Symptomatic Needlessupporting

confidence: 85%

Histopathology of Pinus taeda needles infected by Ploioderma lethale

Jewell

2001

Forest Pathology

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The histopathology of the host/parasite relationship of Pinus taeda needles infected by the Ascomycete Ploioderma lethale and the morphology of the fructifications of the pathogen were investigated. Amphigenous elliptical teleo‐ and anamorph stromata developed only on dead portions of affected needles. Insertion of the teleo‐ and anamorph stromata in the host needle tissue was subepidermal, and the stromata were covered by a shiny to dull black clypeus. Teleomorph stromata frequently coalesced. Abnormal host tissue was primarily confined to tissues external to the endodermis in the symptomatic portion of affected needles, where a collapse of the mesophyll cells was exhibited. An obvious narrowing of affected needles was observed at the distinct juncture of dead and green tissue. Inter‐ and intracellular hyphae colonized the collapsed mesophyll cell regions, endodermal, transfusion, vascular tissues, and resin ducts. Intercellular hyphae and an interface were present in the living mesophyll cells of the green needle tissue subtending the dead terminal portion of affected needles.

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Section: Symptomatic Needlessupporting

confidence: 85%

Histopathology of Pinus taeda needles infected by Ploioderma lethale

Jewell

2001

Forest Pathology

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“…In Chardonnay, callose was limited to some stomata and detected in later phases, starting from 5 dai. Callose contributes to the penetration resistance against some agents of powdery mildew [32] and it is involved in the restriction of bacterial colonization. Callose does not seem to play an important role in limiting the development of P. viticola in other tolerant or resistant Vitis cultivars, since it is not detected until 5 dai [25,33].…”

Section: Resultsmentioning

confidence: 99%

“…They are mainly involved in postinfectional responses to disease agents but they also act as preinfectional barriers [32,36]. During the interaction with P. viticola the main phenolic compounds detected in different grapevine varieties are stilbenes, flavonoids [37-40] and phenolic compounds oxidized by POXs [41], which are accumulated more rapidly and to a higher extent in resistant genotypes in comparison to V. vinifera .…”

Section: Resultsmentioning

confidence: 99%

Phenotypic and histochemical traits of the interaction between Plasmopara viticola and resistant or susceptible grapevine varieties

et al. 2012

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BackgroundGrapevine downy mildew, caused by Plasmopara viticola, is a very serious disease affecting mainly Vitis vinifera cultivated varieties around the world. Breeding for resistance through the crossing with less susceptible species is one of the possible means to reduce the disease incidence and the application of fungicides. The hybrid Bianca and some of its siblings are considered very promising but their resistance level can vary depending on the pathogen strain. Moreover, virulent strains characterized by high fitness can represent a potential threat to the hybrid cultivation.ResultsThe host response and the pathogen virulence were quantitatively assessed by artificially inoculating cv Chardonnay, cv Bianca and their siblings with P. viticola isolates derived from single germinating oospores collected in various Italian viticultural areas. The host phenotypes were classified as susceptible, intermediate and resistant, according to the Area Under the Disease Progress Curve caused by the inoculated strain. Host responses in cv Bianca and its siblings significantly varied depending on the P. viticola isolates, which in turn differed in their virulence levels. The fitness of the most virulent strain did not significantly vary on the different hybrids including Bianca in comparison with the susceptible cv Chardonnay, suggesting that no costs are associated with virulence. Among the individual fitness components, only sporangia production was significantly reduced in cv Bianca and in some hybrids. Comparative histological analysis revealed differences between susceptible and resistant plants in the pathogen diffusion and cytology from 48 h after inoculation onwards. Defence mechanisms included callose depositions in the infected stomata, increase in peroxidase activity, synthesis of phenolic compounds and flavonoids and the necrosis of stomata and cells immediately surrounding the point of invasion and determined alterations in the size of the infected areas and in the number of sporangia differentiated.ConclusionsSome hybrids were able to maintain an intermediate-resistant behaviour even when inoculated with the most virulent strain. Such hybrids should be considered for further field trials.

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“…The cicatrice or wound periderm initially consisted of meristematic tissue that encircled the infection and later differentiated into lignified-suberized barriers. This reaction is well documented in previous studies as a pathogenic (fungal and bacterial) and nonpathogenic (physical injury) response of Prunus species (Samuel 1927;Cunningham 1928;Akai 1959;Adaskaveg 1992). Samuel (1927) described abscission and nonabscission responses in almond and correlated them with different times of the year and stages of leaf development.…”

Section: Discussionmentioning

confidence: 71%

Conidial morphology, host colonization, and development of shot hole of almond caused by Wilsonomyces carpophilus

Adaskaveg¹

1995

Can. J. Bot.

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Morphology and ultrastructure of shot hole disease of almond infected by conidia of Wilsono~rzyces carpophilus were examined using light, scanning, and transmission electron microscopy. The multicelled conidia of the fungus were thick-walled and darkly pigmented. The conidial wall was multilayered and mainly consisted of an electron-dense, outer-wall layer and an electron-translucent, inner-wall layer. Septa of conidia were also multilayered. An electron-translucent zone separated the electron-dense, septa-wall layers of adjacent cells, and this zone extended to the inside of the outer-wall layer of a conidium. Conidia lacked true septa (distoseptate) and germinated by rupturing the outer-wall layers. Germination hyphae penetrated indirectly through stomata or directly through the cuticle into leaf tissue from appressoria that were produced terminally or on lateral branches of germ tubes. An extracellular mucilaginous matrix was commonly observed around hyphae and germ tubes in contact with leaf surfaces. Within leaf tissue, hyphae ramified throughout intercellular spaces and degraded cell walls of epidermal cells apparently without cuticle degradation. Diseased host tissue was tan brown and collapsed; ultrastructurally, diseased leaf cells were reduced in size, nonvacuolated, and had disrupted chloroplasts. A healthy host tissue response, adjacent to an infection site on leaves of potted plants, was the formation of a wound periderm. Within 10-14 days after an infection period (16 h of wetness), the periderm became a lignified-suberized barrier at 15°C or a suberized abscission layer at 22°C based on the histological stains Safranin 0 , Sudan 111, and Sudan Black. At lS°C, no abscission occurred and meristematic cells remained isodiametric but their walls became suberized and lignified, whereas cells adjacent to diseased tissue became lignified. At 22"C, abscission occurred as cells adjacent to diseased tissue became vacuolated, enlarged, and suberized. Subsequently, the epidermis ruptured and the enlarged cells separated along the middle lamella to form an abscission layer. Hyphal growth was limited to the boundaries of the walled-off diseased tissue. Under favorable environmental conditions, hyphae replaced host epidermal cells and aggregated above the palisade layer to form pulvinate sporodochia. Sporodochia consisted of hyphae, numerous sympodially developing conidiogenous cells, and conidia that ruptured the host cuticle.

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Defense Mechanisms in Leaves and Fruit of Trees to Fungal Infection

Cited by 8 publications

References 126 publications

Histopathology of Pinus taeda needles infected by Ploioderma lethale

Histopathology of Pinus taeda needles infected by Ploioderma lethale

Phenotypic and histochemical traits of the interaction between Plasmopara viticola and resistant or susceptible grapevine varieties

Conidial morphology, host colonization, and development of shot hole of almond caused by Wilsonomyces carpophilus

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