In vivo effects of the fungicide ethaboxam on microtubule integrity in Phytophthora infestans.

The effects of ethaboxam (LGC-30473), a novel thiazole carboxamide, on microtubule organization was investigated in Phytophthora infestans (Mont) de Bary (Oomycota) at the light microscope level using standard immunofluorescence and laser scanning confocal microscopy. Hyphal cells were exposed to various concentrations ranging from 0.01 to 1.0 microg ml(-1) of ethaboxam at incubation times of 30, 60 and 120 min. Microtubules were disrupted after exposure to ethaboxam for 30 min at 0.01 microg ml(-1). Similar experimental conditions were used to document the effects of ethaboxam on microtubule integrity in the model fungus Aspergillus nidulans (Eidam) Winter (Ascomycota) and in mammalian mouse 17 clone 1 cells. Under these conditions, there was no evidence to suggest that microtubules in A. nidulans and mouse culture cells were affected by the ethaboxam. These results indicate that ethaboxam is specific for the targeting of microtubule disruption in P. infestans.

Synthesis and fungicidal activity of ethaboxam against Oomycetes.

This study describes the chemical synthesis and intrinsic fungicidal activity of ethaboxam [(RS)-N-(alpha-cyano-2-thenyl)-4-ethyl-2-(ethylamino)-1,3-thiazole-5-carboxamide], a new Oomycetes fungicide. In in vitro tests, ethaboxam showed inhibitory activity against isolates of Phytophthora and some Pythium spp, with MIC values ranging from 0.1 to 0.5 mg litre(-1) for nine isolates of Phytophthora infestans (Montagne) de Bary and from 1.0 to 5.0 mg litre(-1) for eight isolates of Phytophthora capsici Leonian. In tests to determine time and concentration for complete inactivation of each pathogen (five isolates of P infestans and five isolates of P capsici), ethaboxam inactivated all isolates of P infestans within 48h at 10 mg litre(-1) and those of P capsici within 96 h at 10 mg litre(-1). Ethaboxam effectively suppressed development of tomato late blight caused by P infestans and pepper Phytophthora blight caused by P capsici in the studies conducted to determine its preventive, curative, persistent and systemic activity. These results show that ethaboxam has desirable fungicidal characteristics as an Oomycetes fungicide.

Paenibacillus elgii sp. nov., with broad antimicrobial activity.

Two novel spore-forming bacteria with broad antimicrobial activity were isolated from roots of Perilla frutescens. The isolates, SD17(T) and SD18, were facultatively anaerobic and showed variable Gram reaction. Growth was observed between 20 and 45 degrees C. DNA G+C content of SD17(T) was 51.7 mol%, and the major fatty acid was anteiso-C(15 : 0) (54.1 %). 16S rRNA gene sequence similarity of SD17(T) ranged from 98.6 to 91.3 % with other Paenibacillus species. The phylogenetic tree showed that isolate SD17(T) formed a significant monophyletic clade with Paenibacillus koreensis KCTC 2393(T) and Paenibacillus ehimensis IFO 15659(T). DNA-DNA relatedness values for strain SD17(T) with Paenibacillus koreensis KCTC 2393(T) and Paenibacillus ehimensis IFO 15659(T) were 17.4 and 19.8 %, respectively. These isolates thus merit species status within Paenibacillus, for which the name Paenibacillus elgii sp. nov. is proposed. The type strain is SD17(T) (=KCTC 10016BP(T)=NBRC 100335(T)).