Inhibition Effect of Avirulent Pseudomonas solanacearum on the Multiplication of Virulent Isolate in Tobacco Plant

비병원성균주 전처리에 의한 담배세균성마름병균(Pseudomonas solanacearum)의 식물체내 침입 및 증식억제

Significant reduction in disease severity of bacterial wilt (Pseudomonas solanacearum) on the susceptible tobacco cultivar BY 4 was observed until mid-July in a naturally infested field when bacterial suspensions of avirulent isolate were applied to tobacco root zones at one day before and fourty days after transplanting into the field. However, rapid increase in disease severity after mid-July resulted in the same severity $(70\%)$ as on cultivar BY 4 without the application of the avirulent bacterial suspension at the end of the season. Yield increase in cultivar BY 4 was $35\%$ due to the treatment, resulting in $10\%$ price increase. The suppression me chanism did not appear to be dependent upon the inhibition of the virulent bacterial multiplication by the avirulent bacteria in tobacco rhizosphere soil because of no significant difference in the density of the patho genic bacteria between treated and untreated plant root zones. However. penetration of the virulent bacteria into the root systems and their multiplication in tobacco stem were inhibited remarkably by preinoculation with avirulent one, suggesting that those are related to the suppression of disease incidence.

BY4품종의 담배를 포장에 이식하면서 이식 하루전과 40일 후에 비병원성 Pseudomonas solanacearum의 현탁액을 담배근권토양에 관주한 결과 7월 상순까지 세균성마름병 발생 속도가 지연되었으나 그 후에는 방제효과가 급속히 감소되었다. 그 결과 잎담배의 $35\%$ 증수 및 kg당 대금으로 $10\%$의 품질상승 효과를 얻을 수 있었다. 비병원성균주처리에 의한 근권상양내 병원균의 밀도증가억제는 인정되지 않았다. $^{32}P$로 표식된 비병원성균주의 담배뿌리를 통한 침입 및 식물체내 이동이 확인되었으며 비병원성균주에 전접종된 담배에 대하여 병원성균주의 침입 및 식물체내 증식이 억제되었다. 이러한 병원성균주의 식물체내 침입 및 증식억제 현상이 병진전 억제와 관련이 있는 것으로 생각되었다.