解淀粉芽孢杆菌（Bacillus amyloliquefaciens）PG12是从苹果果实中分离获得的对苹果轮纹病（Botryosphaeria dothidea）有良好防效的有益细菌，产生具有抑菌活性的脂肽类化合物Iturin A是其重要的生防机制。关于Iturin A的研究，主要集中在抑菌活性方面，而它与定殖的相关性研究较少。本项目以B. amyloliquefaciens PG12为研究对象，拟通过反向遗传学研究途径，利用基因敲除和功能互补验证等功能基因组学研究方法，结合运动性、生物膜、在苹果果实上定殖量的测定和定殖位点的观察，探究Iturin A与B. amyloliquefaciens PG12在苹果果实上定殖的相关性。本项目不仅有利于揭示解淀粉芽孢杆菌在苹果上定殖的分子机制，而且有助于深入研究解淀粉芽孢杆菌的生防机理。

Apple ring rot disease, caused by Botryosphaeria dothidea, was one of the most important diseases on apple fruits in Asia. The preliminary study of this topic indicates that Bacillus amyloliquefaciens PG12 was one of high antagonistic Bacillus strains isolated from Fuji apple fruits against B. dothidea. Iturin A production by B. amyloliquefaciens PG12 plays a major role in this disease suppression. Iturins were at first mostly studied for their antagonistic activity for a wide range of potential phytopathogens. Recent investigations have shed light on the fact that these iturins can also involved at different levels of the colonization process, which is the precondition to be successful in field application of biocontrol agents. In this study, we aim to explore the relationship between Iturin A and colonization of B. amyloliquefaciens PG12 relying on the way of reverse genetic methods, including ituD disruption and functional complementation, antifungal activity detections in vitro and the analysis of colonization related characters. These results will further demonstrate the role of Iturin A on the colonization process. This study not only helps to reveal the molecular mechanism of colonization in the apple, but also helps to further study the bio-control mechanism of Bacillus.