포도나무 줄기혹병균에 대한 약용식물의 항균활성 및 병발생억제

In vitro and In vivo Antimicrobial Activities of Medicinal Plants against Crown Gall in Grapevine

항암, 항산화, 항균 활성을 나타내는 9종의 약용식물을 이용하여 포도나무 줄기혹병의 억제효과를 조사하였다. 공시한 식물 중에서 개똥쑥(15mm), 맨드라미의 꽃(27mm)과 잎(13mm), 여주의 미성숙 열매(22mm), 상사화 꽃(7mm), 질경이의 꽃(14mm)과 종자(16mm), 초석잠의 뿌리(13mm), 복숭아 나무의 수지(10mm) 추출물 등이 줄기혹병균(Rhizobium vitis)에 대해 항균활성을 나타내었다. 항균활성의 분획물의 최소억제농도를 확인한 결과 개똥쑥, 맨드라미 잎, 여주 미성숙과 분획물은 각각 50,000배, 질경이 꽃 분획물은 10,000배 희석액이 최소억제농도(MIC)로 확인되었다. 개똥쑥, 맨드라미 꽃과 잎, 여주의 미성숙 열매 추출물의 항균활성물질을 column chromatography와 thin layer chromatography(TLC)를 통하여 분획하였다. 핵산/에틸아세테이트와 메탄올/클로로포름(20:80, v/v)으로 전개한 TLC 분석에서 개똥쑥 추출물에서는 Rf 0.36, 0.69, 0.75, 0.84, 0.94, 맨드라미 꽃 추출물은 Rf 0.96, 0.99, 맨드라미 잎 추출물은 Rf 0.92, 0.97, 여주의 미성숙열매 추출물은 Rf 0.85에서 항균 활성의 분획을 획득하였다. 개똥쑥, 맨드라미 잎, 여주 미성숙 열매 추출물을 물에 희석(500, 1,000, 2,000배)하고 온실에서 R.vitis를 접종한 '거봉' 식물체에 7일 간격으로 관수한 결과, 개똥쑥 희석액은 100%, 맨드라미 잎 추출물(500배 희석액)은 67%, 여주 미성숙 열매 추출물(500배 희석액)은 83.3%의 억제효과를 나타내었다. 이러한 연구 결과는 약용식물 추출물이 포도나무 줄기혹병을 방제할 수 있는 친환경 제제로서의 적용가능성을 제시한 것이라 할 수 있다.

The objective of this study was to evaluate the antimicrobial activities of 9 kinds of medicinal plants against crown gall in grapevine. The medicinal plants extracted with several solvent systems were screened for in vitro antibacterial activity by the disc diffusion method. The ethanol and ethyl acetate extracts from magic lily flowers, tachys roots, asian plantain flowers and seeds, sweet wormwood leaves, stems and flowers, immature bitter melon fruits, cockscomb flowers, and peach tree resin showed in vitro antimicrobial activities against Rhizobium vitis with growth inhibition zones ranging from 10 to 27 mm in diameter. The minimum inhibitory concentration values of extracts against R.vitis ranged from 10,000 in Asian plantain flower and 50,000 fold diluted extracts in sweet wormwood flowers, stems, leaves, cockscomb leaves and immature bitter melon fruits. The active fractions of ethyl acetate and ethanol extracts from the medicinal plants were partially separated through silica gel column chromatography and thin layer chromatography (TLC). The active fractions were separated at Rf 0.36, 0.69, 0.75, 0.84, and 0.94 in sweet wormwood extracts, Rf 0.96 and 0.99 in cockscomb flower extracts, Rf 0.92 and 0.97 in cockscomb leaf extracts, and Rf 0.85 in immature bitter melon fruit extracts in TLC analysis developed with hexane:ethyl acetate (20:80, v/v) and methanol:chloroform (20:80, v/v). Among extracts from plants with in vitro antimicrobial activities, sweet wormwood, cockscomb leaves, and immature bitter melon fruits showed in vivo antimicrobial activities with inhibition activity of 100, 67, and 83.3%, respectively, in 'Kyoho' grapevine inoculated with R. vitis compared with the untreated control. These findings indicate that extracts of medicinal plants could be used as sustainable candidates to control crown gall disease caused by R. vitis in grapevines.