Nature and location of increased ribonuclease activity in potato leaves following infection with Phytohpthora infestans

Pitt, D.

doi:10.1016/s0007-1536(76)80051-4

Cited by 5 publications

(5 citation statements)

References 12 publications

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“…The enzyme ribcnuclease has been extensively studied in diseased plants, due to its central role in RNA metabolism (Chakravorty & Shaw, 1977). The substantial increases detected in the present study appear similar to those observed in other susceptible hostpathogen combinations (Scrubb et al, 1972;Pitt, 1976). Diethyl pyrocarbonate (DEP), an established nuclease inhibitor (Solymosy eta/., 1968), eliminated the post-infectional increase while activity in extracts from control seedlings and fungal spores was unaffected.…”

Section: Discussionsupporting

confidence: 73%

“…Alterations in the activity and subcellular location of acid hydrolase enzymes have been recorded in several plant diseases caused by fungi (Staples &Stahmann, 1964;Scrubb etal., 1972;Reddy et aL, 1973;Pitt, 1976;Rai et al, 1979). Such changes may be important in pathogenesis and in particular in the necrosis of host cells (Pitt & Galpin, 1973;Mansfield & Sexton, 1974).…”

Section: Discussionmentioning

confidence: 99%

“…The insensitivity of fungal RNase to DEP inhibition has been previously demonstrated with Phytophthora infestans (Mo'iit.) de Bary (Pitt, 1976), and it is therefore probable that increased RNase activity is of host origin.…”

Section: Discussionmentioning

confidence: 99%

“…The possible origm of the increase in RNase activity in susceptible infected tissues was investigated using several enzyme inhibitors (Pitt, 1976), in extracts of cauliflower infected with isolate Cl (Table 2). Diethyl pyrocarbonate (DEP) differentially inhibited RNase in infected tissue extracts, reducing the activity to levels similar to those found in uninfected controls.…”

Section: Ribonuclease Inhibitorsmentioning

confidence: 99%

“…Amounts of chlorophyll and electrolyte leakage, which have been used to detect permeability changes in infected tissues (Hall & Wood, 1973), were monitored at daily intervals following inoculation. The activities of several enzymes implicated in pathogeoesis and cell necrosis in other hostpathogen systems (Reddy et al, 1973;Mansfield & Sexton, 1974;Cohen, 1975;Ohguchi & Asada, 1975;Pitt, 1976;Rai et al, 1979) were also measured, and any changes related where possible to the differing degrees of pathogen development and host resistance.…”

Section: Introductionmentioning

confidence: 99%

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Development and physiology of infection by the downy mildew fungus Peronospora parasitica (Pers. ex Fr.) Fr. in susceptible and resistant Brassica species

Kluczewski

Lucas

1982

Plant Pathology

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The growth of two isolates of the downy mOdew fungus Peronospora parasitiea, one obtained from cauliflower (Brassica oleracea) and the other from oilseed rape (B. napus) was assessed in their respective hosts of origin, and also in the alternative combination. Both isolates were capable of infecting either host, but there were marked contrasts in the time course and extent of mycelial development, the amounts of associated host-cell necrosis, and eventual intensity of sporulation. Oilseed rape, which was partially resistant to the isolate from cauliflower, exhibited extensive necrosis of mesophyll cells, in conjunction with reduced mycelial development, and delayed and reduced sporulatioo by the pathogen. The isolate from, oilseed rape was virulent on both host species. Pathogenesis in the susceptible combinations was accompanied by large increases in electrolyte leakage, and increased activity of the enzymes /3-glucosidase, ribonuclease, and perO'Xidase. Effects OD chlorophyll content were variable and activities of acid phosphatase and acid phosphodiesterase were unaffected. Electrophoretic analyses of extracts from fungal sporangia and infected seedlings indicated that the large increases in j3-glucosi,dase were of pathogen origin, while evidence from inhibitor studies suggested that enhanced ribonuclease activity was due to a new post-infectional fonn of the enzyme. The significance of these findings is discussed in relation to pathogenesis and host resistance mechanisms.

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Ribonuclease Inhibitorsmentioning

confidence: 99%