Abstract
A bacterial disease of small red bean (Phaseolus angularis) was observed on field-grown plants in Suwon in year 2003. Leaf symptoms initially appeared as water-soaked spots that gradually enlarged, became flaccid and necrotic and were often bordered by a small zone of lemon yellow tissue. In the case of severe infection, dead leaves were defoliated. Pod symptoms consisted of the lesions that were generally circular, slightly sunken and dark reddish brown. Isolation made from diseased leaves on yeast extract dextrose calcium carbonate agar yielded nearly pure cultures of a yellow-pigmented bacterium typical of a xanthomonad. Three bacterial strains were purified and used for further tests. Pathogenicity of strains was confirmed on 3-week-old small red bean plants sprayed with bacterial suspensions containing $10^8 cfu/ml$ of phosphate buffered saline. The representative Xanthomonas strains isolated from small red bean were compared with X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans type strains for fatty acid profiles, biochemical tests and metabolic fingerprints using Biolog GN2 microplate, showing that all outcomes were indistinguishable between our isolates and reference strains. Two of three strains produced a melanin-like brown pigment extracellularly on King's medium B agar. These results suggest that this new small red bean disease observed in Suwon is bacterial fuscous blight caused by X. axonopodis pv. phaseoli and X. axonopodis pv. phaseoli var. fuscans.
2003년 수원의 팥 재배 포장에서 새로운 병해가 발견되었다. 처음에는 잎에서 수침상 점무늬가 형성되고 점점 커져 주위로 노란색의 테두리를 형성하는 진갈색의 반점을 형성한다. 심해지면 잎이 떨어지고 잎자루 및 꼬투리에도 진갈색의 병반이 형성된다. YDC 배지에서 병원세 균을 순수 분리하였을 때 Xanthomonas속 세균의 전형적인 특징인 노란색 색소를 띤 세균이 형성되었다. 분리된 세균을 $10^8 cfu/ml$로 현탁한 후 3 주 동안 자란 팥과 콩에 분무 접종하여 병원성을 확인하였다. 지방산 조성 및 함량과 다양한 탄소원 이용정도를 이용하여 분리세균 SL4311은 X. axonopodis pv. phaseoli로 SL4309와 SL4310 은 X. axonopodis pv. phaseoli var. fuscans로 동정하였으며 이 병을 팥의 세균성잎마름병으로 명명하였다.
