The oospore stage of Plasmopara obducens, impatiens downy mildew.
Mycologia
; 111(4): 632-646, 2019.
Article
de En
| MEDLINE
| ID: mdl-31136264
ABSTRACT
Impatiens downy mildew is caused by Plasmopara obducens, a pathogen known in the United States for over a hundred years, but newly attacking ornamental Impatiens walleriana in production and in the landscape. Little is known about the life cycle of P. obducens; thus, in this study an attempt was made to determine whether the pathogen is homothallic or heterothallic. Fourteen single-sporangium isolates and three single-zoospore isolates were used in single and dual inoculations of stem tissue to see whether the pathogen was homothallic or heterothallic; all isolates tested were able to produce oospores when inoculated singly, suggesting homothally. Cold treatment at 0 C for at least 1 mo induced oospores to germinate and produce primary sporangia. Inoculation of plant tissue with germinating oospores resulted in infection. Other incubation temperatures (-10, 10, and 20 C) did not induce germination, but fluctuating temperatures (between -10 and 0 C, or 0 and 10 C) induced some germination. Spores incubated at -10 C had significantly thicker walls than spores incubated at other temperatures. Evidence suggests that oospores can serve as an overwintering stage.
Mots clés
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Oomycetes
/
Maladies des plantes
/
Spores
Langue:
En
Journal:
Mycologia
Année:
2019
Type de document:
Article