生防芽胞杆菌在胡椒根际定殖及其招募机制研究

Bacillus subtilis have been widely used as biological control agents against various plant diseases over the world, because of their broad-spectrum, bear-hoarding and environmental-friendly characters. Poor root colonization of the beneficial bacteria was long ago considered a factor that can limit biocontrol efficacy. Recently, it has been proven that rhizoplane colonization indeed is required for biocontrol mechanisms. In the past, scientists make lots of efforts to reveal the root colonization mechanisms. But, almost all the works were focused on food crops and vegetables, which are planted in temperate regions. Colonization in tropical plants has rarely been reported, especially in spice crop black pepper. In previous, a strain B. subtilis Z was obtained from black pepper root, which showed excellent effects on the control of foot rot disease of black pepper. This project aimed to reveal the rhizoplane colonization and bacterial recruitment in black pepper by B. subtilis Z. First, the B. subtilis Z strain will be marked by GFP to monitor the root colonization development. Then effects on four colonization and recruitment traits, growth, chemotaxis, motility and biofilm, were observed in the response of black pepper root exudates. Last, the root exudates compounds will be screened to clear the recruitment agents. This project will give us a panoramic image that how the B. subtilis Z strain recruites and colonizes in black pepper rhizoplane. It is helpful for us to understand the colonization mechanism and make better use of biocontrol bacteria.

生防菌的田间防效与其在作物根表的定殖能力密切相关。定殖能力低下已成为许多生防菌商品化应用的制约因子。目前国内外已有的定殖研究主要集中在温带粮棉蔬菜等大宗作物上，在热带特色香料作物胡椒上基本空白。之前，项目申请单位已从胡椒根中筛选得到了高效防治胡椒瘟病的菌株Bacillus. subtilis Z（已获得国家专利授权）。在此基础上，本项目提出该菌株在胡椒根际定殖及其招募机制研究。内容包括：监测生防菌B. subtilis Z在胡椒根表定殖的时空动态；分析胡椒根系分泌物对生防菌生长、趋化性、运动和生物膜等定殖招募相关性状的影响；筛选胡椒根系分泌物中有助于生防菌招募的活性成分。本项目的完成能够明确B. subtilis Z在胡椒上的定殖特征并初步揭示其招募机制，有助于加深"生防菌-胡椒"互作的认识，同时也为改善生防菌定殖能力、开辟胡椒瘟病绿色高效防治途径提供靶标位点和理论依据。

根际定殖能力低下已成为许多生防菌商品化应用的制约因子。目前国内外已有的定殖研究主要集中在温带粮棉蔬菜等大宗作物上，在热带特色香料作物胡椒上基本空白。本项目选择热带特色作物胡椒和胡椒瘟病生防菌Bacillus. subtilis VD18R19为研究对象，开展了生防菌Bacillus subtilis VD18R19在胡椒根际定殖情况检测、胡椒根系分泌物组分分析、招募物质筛选及其对生防菌定殖性状和基因表达水平影响等研究，明确了生防菌在胡椒上定殖的空间位置偏好和时间数量变化规律；发现胡椒根系分泌物中的草酸、酒石酸和柠檬酸能够在液体环境中吸引生防菌趋向运动，能够在半固体表面增强生防菌群集运动，初步揭示了胡椒根系分泌物对生防菌B.subtilis VD18R19的招募机制。有助于加深“生防菌-胡椒根系”互作机制的认识，也为改善生防菌定殖能力、开辟胡椒瘟病绿色高效防治途径提供了靶标位点和理论依据。