Life Cycle of Mycosphaerella brassicicola (Duby) Lindau and Ascospore Production in vitro

• Published in: Journal of phytopathology Vol. 139; no. 4; pp. 298 - 308
• Main Authors: Götz, M., Zornbach, W., Boyle, C.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.1993; Blackwell
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Phytopathology. Animal pests. Plant and forest protection; Systematics. Morphology. Development cycle. Physiology; Plant pathogen; Ascospore; Host agent relation; Plant leaf; Brassica oleracea var. capitata; Epidemiology; In vitro; Fungi; Life cycle; Symptomatology; Vegetable crop; Cruciferae; Sporulation; Seasonal variation; Dicotyledones; Angiospermae; Ascomycetes; Spermatophyta; Mycosphaerella brassicicola; Thallophyta
• ISSN: 0931-1785; 1439-0434
• DOI: 10.1111/j.1439-0434.1993.tb01431.x

The germ‐hyphae of the M. brassicicola ascospores penetrated the host leaves (white cabbage) 10 days after inoculation during the summer at 17 °C. The penetration occurred without exception by way of the stomata. Following a period of intercellular growth which lasted up to 15 days, brownish discolourations of the host cell walls and the destruction of mesophyll cells were observed. At this stage of infection, fruit‐body primordia developed from hyaline, thick‐walled, granulated mycelium, which blackend after conglomeration due to melanine deposits. The further ascocarp development was ascolocular. Ascospore production of M. brassicicola was increased in vitro by variation of the incubation temperatures, medium‐pH and irradiation. The highest sporulation rate was obtained in cultures on vegetable juice medium adjusted to pH 6, incubated at 17 °C and subjected immediately after onset of growth to 4 h UVA radiation. The percentage of germinated ascospores (70 %) corresponded to that of the dark incubated controls. Fructification and infectivity were subject to seasonal fluctuations under growth chamber conditions.