오이 유묘와 과실을 활용한 검은별무늬병에 대한 저항성 품종 검정 방법

This study was conducted to elucidate the cultural and pathogenic characteristics of Cladosporium cucumerinum PT1 and resistance of 81 commercial cucumbers (Cucumis sativus). Cucumber leaves and fruits appeared as scab were collected from a plastic film house located in Pyeongtaek, Gyeonggi-province, Korea in late March, 2015. A casual fungus was isolated from the diseased fruits on potato dextrose agar and it was identified as C. cucumerinum PT1 based on the morphological characteristics. To find out the effect of wounding and fruit size on the development of cucumber scab, small (20 cm long, commercially mature fruit) size cucumber fruits were harvested, C. cucumerinum PT1 pathogens were inoculated with a single droplet of suspension ($1{\times}10^5$ spores/ml) on wounded or unwounded cucumber fruits. Small fruits were completely damaged with showing severe water-soaking symptoms and fast pathogen growth regardless of wounded or unwounded. Meanwhile slight water-soaking symptoms on medium and large size fruits occurred and disease development into plant tissues was observed only on wounded fruits. Disease resistance of 81 commercial cucumber cultivars was evaluated on third-stage seedlings and small fruits by inoculating suspension ($1{\times}10^5$ spores/ml) of C. cucumerinum PT1. As a result, mini and pickling cultivar groups were resistant, 'Cheoeumcheoreom' cultivar was symptomless and the other cultivars were resistant to medium resistant. On the other hand, most of cucumber cultivars belonging to the other groups were susceptible. Disease resistance of cucumber against cucumber scab was significantly different among cultivars and a few cucumber cultivars showed different disease resistant responses to two bioassay methods using seedlings and small fruits. Therefore, to screen scab resistance in cucumber, a test using both fruits and seedlings is advisable. We think that the selected resistant cultivars can be used to control cucumber scab effectively under the farmhouse condition. 본 연구는 검은별무늬병균의 배양적 및 병원학 특성을 구명하고, 81개 시판 오이 품종의 저항성 여부를 검정하기 위해 수행되었다. 시험균은 2015년 3월 말 경기도 평택에 위치한 시설 오이 재배농가에서 채취한 병든 과실로부터 분리하였고 PDA상에서 배양하면서 형태적인 특성에 근거하여 검은별무늬병균(C. cucumerinum PT1)으로 동정되었다. 상처 유무와 과실 크기가 검은별무늬병의 발생에 미치는 영향을 규명하기 위해 과일 크기를 유과(10 cm 미만), 중과(10-20 cm), 대과(20 cm 초과)로 구분하고 과실 크기별로 상처와 무상처 조건으로 오이 과실표면에 $1{\times}10^5$ 포자/ml 농도의 병원균을 접종하였다. 작은 과실에서는 표면 상처 여부에 관계없이 심한 수침상의 병반과 빠른 병원균 생장을 보이면서 피해정도가 매우 컸던