Some Aspects of Host-Pathogen Interactions

Daly, J.M.

doi:10.1007/978-3-642-66279-9_2

Cited by 16 publications

(4 citation statements)

References 51 publications

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“…Associated with these changes is an increase in the numbers of localized infections and a reduction in numbers of neerotic cells, suggesting more effective localization of the fungus by fungistatic mechanisms. However, this pattern of diminishing susceptibility is typical of biotrophie systems in general (Bell, 1980) and may also reflect diminishing adaptive capability of the leaf cells and eventual failure to adjust to a balaneed system oi compatibility (Daly, 1972(Daly, , 1976bHaberlach et al. 1978), This explanation appears the more plausible, since the reverse pattern occurs with most necrotrophic systems in leaf tissues (Bell, 1980 and references contained therein) and therefore the changes cannot simply be explained by general changes in levels of resistance.…”

Section: Discussionmentioning

confidence: 99%

The establishment of systemic infection in leaves of oilseed rape by Leptosphaeria maculans

Hammond

Lewis

1987

Plant Pathology

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In a series of growth room experiments in which leaves of Brassica napus var. oleifera were inoculated with ascospores or pycnidiospores of Leptosphaeria maculans successful infections progressed through three consecutive phases. Initial establishment in the mesophyll was succeeded by a phase of intercellular exploration, when hyphal proliferation was highly variable and host cell necrosis always ensued, and then by a systemic phase when hyphae were consistently sparse. Host cells associated with the hyphal front were capable of autofluorescence, accumulation of vital stains and plasmolysis, indicating that they were viable and that the pathogen was biotrophic throughout this sequence. During either of the first two phases permanent fungistatic containment, involving the formation of vesicles by disintegration of the hyphae, often occurred. Localization at the first phase was symptomless; at the second it was signified by a lesion with a clearly defined margin. There was a negative correlation between biotrophic potential and necrotrophic potential of three pathogenic isolates, on both the moderately susceptible cultivar Primor and the resistant cultivar Jet Neuf. As leaves aged, a progressively larger proportion of infections failed to become systemic. With increasing inoculum load, symptomless localization of infection diminished, the phase of necrosis extended, and the probability of irreversible systemic development increased.

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Section: Discussionmentioning

confidence: 99%

The establishment of systemic infection in leaves of oilseed rape by Leptosphaeria maculans

Hammond

Lewis

1987

Plant Pathology

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“…This could operate simply, for example, through a 'sink' effect (Hwang & Heitefuss, 1982) in which the presence of one isolate alters the metabolites available for another. Daly (1976) pointed out that this need not necessarily be so; the responses to the individual isolates in a multiple test are observed by the interaction that affects both isolates and the host. The multiple inoculation tests did reveal some differences between the isolates other than the major qualitative effects.…”

Section: Discussionmentioning

confidence: 99%

Host‐mediated interactions between pathogen genotypes

1984

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Barley c ltivars with different resistance genes were inoculated with various sequences of virulent and non‐virulent isolates of Erysiphe graminis f.sp. hordei. The resistance induced in incompatible reactions decreased infection by virulent isolates while, conversely, the degree of susceptibility induced in compatible reactions was sufficient to increase the ability of normally non‐virulent isolates to infect a resistant host. The net effect of interactions was always overall reduction of conidial production when compared with inoculation of a virulent isolate alone. Each interaction between isolates was dependent on the host cultivar, the pathogen isolates used and on the inoculation sequence. Often, induced resistance was most obvious when a nonvirulent isolate was inoculated prior to a virulent isolate. Induced susceptibility was usually more apparent when the virulent isolate was inoculated first. However, on the cultivar Wing, induced susceptibility was more apparent following prior inoculation of a non‐virulent isolate. On the cultivar Hassan, prior inoculation with a virulent isolate sometimes induced susceptibility, but in some cases more susceptibility was induced by prior inoculation with a non‐virulent isolate. In the latter instances, although relatively little infection developed, the majority of the spores produced were those of the normally non‐virulent isolate. There was some evidence of non‐virulent isolates acquiring the ability to infect normally incompatible hosts. This effect disappeared after several generations in the absence of the virulent isolate.

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“…Infection of plants by bacterial pathogens cause deleterious shifts in the physiological and biochemical processes required for normal cellular reproduction, function, and differentiation ( Daly, 1976 ). At the physiological level, the interaction between plants and pathogenic bacteria is predominantly manifested in osmotic adjustment, photosynthesis, oxidation and antioxidation, and synthesis of defense enzymes ( Liang et al, 2006 ).…”

Section: Introductionmentioning

confidence: 99%

Seed-Borne Erwinia persicina Affects the Growth and Physiology of Alfalfa (Medicago sativa L.)

et al. 2022

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Seed-borne Erwinia persicina can be transmitted globally via alfalfa (Medicago sativa L.) seed trade, but there is limited information about the impact of this plant-pathogenic bacterium on alfalfa plants. In this study, strain Cp2, isolated from alfalfa seeds, was confirmed by whole-genome sequencing to belong to E. persicina. Subsequently, the effects of Cp2 on alfalfa growth and physiology were evaluated by constructing a rhizosphere infection model. Strain Cp2 had a strong inhibitory effect on the elongation and growth of alfalfa roots, which was very unfavorable to these perennial plants. Furthermore, an increased number of leaf spots and yellowing symptoms were observed in plants of the Cp2 group from day 10 to day 21 and the strain Cp2 was re-isolated from these leaves. Correlation between growth and photosynthetic parameters was analyzed and the significant decreases in fresh weight and root and plant lengths in the Cp2 group were related to the marked reduction of chlorophyll b, carotenoid, transpiration rate, and stomatal conductance of leaves (r > 0.75). In addition, nine physiological indicators of root, stem, and leaf were measured in the plants 21 days after treatment with Cp2. The physiological response of root and leaf to Cp2 treatment was stronger than that of stem. The physiological indicators with the greatest response to Cp2 infection were further explored through principal component analysis, and superoxide dismutase, peroxidase, ascorbate peroxidase, and soluble protein showed the greatest changes in roots, stems, and leaves (P < 0.001). Among tissues, the commonality was the change of soluble protein. Therefore, soluble protein is speculated to be a physiological marker during alfalfa–E. persicina interactions. These findings indicate that once E. persicina spreads from alfalfa seeds to the rhizosphere, it can invade alfalfa roots and cause disease. This study demonstrates that this plant pathogenic bacterium may be a potential threat to new environment when they spread via seed trade and these “dangerous hitchhikers” warrant further attention, especially in the study of bacterial diseases in pasture-based production systems.

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Some Aspects of Host-Pathogen Interactions

Cited by 16 publications

References 51 publications

The establishment of systemic infection in leaves of oilseed rape by Leptosphaeria maculans

The establishment of systemic infection in leaves of oilseed rape by Leptosphaeria maculans

Host‐mediated interactions between pathogen genotypes

Seed-Borne Erwinia persicina Affects the Growth and Physiology of Alfalfa (Medicago sativa L.)

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