【作者】 刘菊；

【导师】 张明方；

【作者基本信息】 浙江大学 ， 园艺学， 2012， 硕士

【摘要】 本文通过PDA培养及田间灌根的方法,研究不同浓度的鼠李糖脂对西瓜枯萎病菌的孢子萌发、菌丝生长、孢子结构及葡聚糖酶和几丁质酶活性的影响。进而研究鼠李糖脂对西瓜枯萎病的防治效果,初步探索鼠李糖脂的对西瓜枯萎病菌的作用机制。主要研究结果如下：1鼠李糖脂对西瓜枯萎病菌菌丝生长和孢子萌发的影响用浓度分别为0.5g/L、1.0g/L、2.0g/L、5.0g/L的鼠李糖脂PDA培养基培养西瓜专化型枯萎病病菌,其中不含鼠李糖脂的PDA培养基作为对照,结果发现鼠李糖脂对西瓜枯萎病病菌菌丝生长及孢子的萌发均表现出的抑制作用,鼠李糖脂为0.5g/L时即可明显抑制西瓜枯萎病病菌生长,鼠李糖脂浓度的越高,其抑制作用越明显,当浓度达到5.0g/L时几乎是完全地抑制了菌丝的生长。相对应时期显微镜下观察孢子的数量发现,枯萎病菌孢子萌发的数量也越来越少。2鼠李糖脂田间灌根对西瓜枯萎病的防治效果研究分别用0.5g/L、1.0g/L、2.0g/L、5.0g/L的鼠李糖脂溶液灌根,等量清水灌根作为对照。结果发现,鼠李糖脂对西瓜枯萎病的发生具有较好的延缓作用,当鼠李糖脂浓度为0.5g/L时,发病初期的发病率与对照即呈现出显著差异,并且鼠李糖脂浓度越高,发病率就越低,但是鼠李糖脂浓度过高对西瓜幼苗的生长具有一定的抑制作用,综合因素考虑,鼠李糖脂防治西瓜枯萎病的最佳浓度为1.0g/L。3鼠李糖脂对西瓜枯萎病菌孢子结构的影响分别用0.1g/L和0.5g/L的鼠李糖脂溶液处理西瓜转化型枯萎病菌的孢子悬浮液,清水处理作为对照,在显微镜下观察,结果发现,鼠李糖脂对孢子的表面结构变化不大,但是鼠李糖脂对孢子的内部结构影响比较明显,并有泡化现象出现,并且鼠李糖脂浓度越高,孢子内部的结构的泡化现象越明显。4鼠李糖脂对植株体内与抗性有关的酶活性的影响本研究中证明了鼠李糖脂能够在温室环境下通过诱导植物抗性反应来防御西瓜幼苗枯萎病。通过对几丁质酶和β-1,3-葡聚糖酶的活性测定,表明不同浓度的鼠李糖脂处理48h以后两种酶的活性均有显著的增加。我们发现在叶喷鼠李糖脂4天后,离体植株真叶中几丁质酶和p-1,3-葡聚糖酶的活性都呈现出一致的升高,尤其在鼠李糖脂浓度为1.0g/L时,β-1,3-葡聚糖酶和几丁质酶的活性分别比对照高63.04%和49.95%,这也说明鼠李糖脂能够有效引发西瓜的抗性反应来抵抗真菌的侵染。更多还原

【Abstract】 In this study, we investigated the influence of rhamnolipids on the spore germination, mycelium growth, the structure of spores and the activity of chitinase and beta1,3-glucance enzyme through the methods of the PDA training and irrigation of watermelon root, and attempted to study the effect of different concentrations of rhamnolipid in preventing the disease incidence of watermelon and preliminary explored the mechanism of rhamnolipid in preventing the disease incidence of watermelon. The main research results were as follows:1The influence of rhamnolipid treatments on the spore germination and mycelium growth of fusarium wilt of watermelonThe concentrations of rhamnolipid were0.5g/L,1.0g/L,2.0g/L,5.0g/L of PDA medium, while PDA training fusarium oxysporum f.s p.niveum, having no rhamnolipid PDA medium was used as control. The results showed that rhamnolipid obviously inhibited the spore germination and mycelium growth of fusarium wilt. When the concentration was0.5g/L, the inhibition was the least, which increased gradually as the concentration increased, while with the concentration of5.0g/L, a complete inhibition of the growth of fusarium wilt was observed. Likewise, rhamnolipids also influenced number of spores. It was found that there was inverse relationship between rhamnolipid concentrations and number of spores. The numbers of spores were decreasing with the increasing concentrations.2The effect of rhamnolipid irrigation of watermelon root on watermelon fusarium wiltThe concentrations of rhamnolipid0.5g/L,1.0g/L,2.0g/L,5.0g/L, and equivalent water as control were used to irrigate watermelon root. The results indicated that rhamnolipid obviously inhibited the fusarium wilt of watermelon. When the concentration was0.5g/L, they presented a significant difference as compared to control. The higher concentrations showed the the lower rates of disease incidence. But very higher concentrations of rhamnolipid inhibited the growth of watermelon seedlings. Hence, keeping in view a few factors, the optimum concentration was1.0g/L.3The influence of rhamnolipid treaments on spores surface and the internal structure of fusarium oxysporiumThe fusarium oxysporium spore suspension with0.1g/L and0.5g/L of rhamnolipid, and clear water treatment as control, were observed under a microscope. We noted that the influence of rhamnolipid on spores’surface structure was not significant, but the internal structure was significant, and appeared like a bubble. As the concentration was getting higher, the devastating effect on internal spores’ structures was also increasing.4The influence of rhamnolipid on enzymes activities related to fusarium wilt resistance.This study proved that the rhamnolipid in the greenhouse environment can induce plant resistance to defend the watermelon blight. The chitinase and beta1,3-glucance enzyme activity determination showed that after48h of different concentrations of rhamnolipid treatments, two kinds of the enzyme were significantly increased. We found that four days after foliar spray treatments, the activity of chitinase and beta1,3-glucance enzyme presented a consistent increase, especially when the concentration of rhamnolipid was1.0g/L, the activities of beta1,3-glucance (63.04%) and chitinase (49.95%) were higher than the control. Hence it was concluded that rhamnolipid can effectively protect watermelon from fungal infection.更多还原