蕹菜對蕹菜白銹菌的抗病性研究

Abstract

蕹菜（Ipomoea aquatica Forsk.）為台灣重要的夏季蔬菜，卻容易感染白銹病。由子葉感染法感染蕹菜幼苗的結果發現，白籽竹葉蕹菜對於白銹病的抗病能力最強。在可能與抗病相關的蕹菜生理性狀探究中，氣孔密度、光合色素含量（葉綠素a、葉綠素b和類胡蘿蔔素）、以及葡萄糖與果糖濃度對蕹菜的幼苗發病率有非線性正相關，而蔗糖濃度與幼苗發病率成負相關，其中氣孔密度、葉綠素a、葉綠素b、葡萄糖與果糖濃度之XY散佈圖數據呈分群的現象。植株園藝性狀對蕹菜感染白銹病的嚴重程度成複迴歸關係，共有六種園藝性狀參與，此複迴歸方程式對罹病率的預測度可達六成。進一步以逢機引子增殖多型性分子標誌技術(RAPD)分析強抗病品系2002-026與感病品系之間的差異，逢機引子O15在相同PCR條件下，顯示強抗病種2002-026有一段位於1500 bp附近的DNA分子標誌，而其他感病品系則無。我們期望此研究可作為未來篩選抗病品系或抗病基因的基礎。

Water spinach (Ipomoea aquatica Forsk.), an important summer vegetable in Taiwan, is easily infected by Albugo ipomoeae-aquaticae, in the result of white rust disease. By cotyledon inoculation, our result shows ‘white-seed Jwu Yeh’ lines were most strongly resistant to white rust disease. We also surveyed several factors of water spinach to evaluate the association with disease proportion; Such as stomatal density of cotyledon, contents of photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids), concentration of glucose and fructose had positive correlation with disease proportion of juvenile stage in non-linear regression. On the other hand, the concentration of sucrose became negative correlation in simple linear regression. The XY scattered graphs of stomatal density, chlorophyll a, chlorophyll b, glucose and fructose with disease proportion were suggested that they exhibited a grouping relationship. Besides, there was multiple regression correlation between six horticultural characteristics and disease severity. From r2, the predictive power of the multiple regression equation would exceed 0.6. We further used Random Amplified Polymorphic DNA (RAPD) to analyze the different banding patterns between one strong resistance line, 2002-026, and other susceptive lines. The random primer O15 produced an unique band (about 1500 bp) which is present only in the lane of DNA amplified from line, 2002-026, but absent in others. We hope the results of our investigation could help in the further research on resistance breeding and defense gene screening.