Production and release of the phytotoxin prehelminthosporol by Bipolaris sorokiniana during growth
1993
Nilsson, P. | Akesson, H. | Jansson, H.B. | Odham, G.
Toxin production by Bipolaris sorokiniana and toxin release from spores and hyphae were studied during a 3-week culture period. Prehelminthosporol was quantified in hyphae and surrounding liquid medium by reverse phase HPLC. To evaluate early toxin release during germination of spores a GC method was developed. The concentration of prehelminthosporol was 4.8 pg/spore in the nongerminated spores. Prehelminthosporol was released on contact with water prior to germination. The maximum concentration of prehelminthosporol was reached after 12 days in the liquid medium and after 14 days in the hyphae. After approximately 6 days' incubation and until day 16 a constant amount of about 0.6 microgram of prehelminthosporol/mg hyphae was found in the liquid medium. The amount of prehelminthosporol released from the spores was calculated to give a concentration of 0.1-0.3 micrograms/microliter in barley cells, a concentration dose approximately that which has previously been shown to produce necrosis in leaves. We thus propose that prehelminthosporol plays a major role in the early stages of infection of barley by B. sorokiniana.
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