LysR家族调控因子BysR调控Burkholderia sp. JP2-270生防活性机理研究

Rice sheath blight is a fungal disease caused by Rhizoctonia solani and one of the most serious diseases in rice production. Burkholderia sp. JP2-270, isolated from the rhizosphere of rice, is a biocontrol bacterium which can effectively inhibit the growth of R. solani. Previous studies have found that BysR, a transcriptional regulatory protein of LysR type, plays a key role in the inhibition of Burkholderia sp. JP2-270 against Rhizoctonia solani. We plan to study the role of BysR involved in the antagonism of JP2-270 against R. solon through transcriptome, molecular biology and metabolic analysis in this study. Pre-research of this study revealed that the synthetic gene cluster of occidiofungin, a glycopeptide, is regulated by BysR. Occidiofungin has antifungal activity, and its synthesis is regulated by LuxR-type pathway-specific transcription regulators AmbR1 and AmbR2. At present, no studies have shown that occidiofungin synthesis is also regulated by other types of transcriptional regulators. Therefore, the problems that need to be solved in this study are as follows. First, we need to confirm that JP2-270 can synthesize occidiofungin-like substances and that they can inhibit rice sheath blight. Second, we need to clarify the synthesis mode of occidiofungin regulated by BysR. This study will expand the research scope of occidiofungins on fungal diseases, and enrich the regulatory network of the this compound. This study provides a theoretical basis for optimizing the synthesis of occidiofungins-like substances.

水稻纹枯病是由立枯丝核菌引起的一种真菌性病害，是水稻生产中最严重的病害之一。Burkholderia sp. JP2-270是本研究室自主分离得到的一株能有效拮抗水稻纹枯病菌的生防细菌。前期研究发现LysR类型的转录调控蛋白BysR对JP2-270抑制水稻纹枯病菌起关键作用，本申请项目拟通过转录组测序分析、分子生物学技术和代谢分析的方法研究BysR在JP2-270抑制水稻纹枯病菌方面所扮演的角色。本申请项目预研结果显示，一种糖肽类物质-occidiofungin的合成基因簇受BysR调控。项目需解决的问题包括：1. 证实JP2-270能够合成occidiofungin类物质，且该物质对水稻纹枯病具有抑制作用。2. 明确JP2-270中的LysR类型的全局转录调控蛋白-BysR调控occidiofungin的合成模式。

抗真菌糖肽occidiofungin是一种由某些伯克霍尔德氏菌产生的高效抗真菌次生代谢物。负责occidiofungin生物合成的ocf基因簇受同一基因簇内ambR同源物编码的簇内特异性调控因子调控，而occidiofungin生物合成与核心调控网络的连接程度尚不清楚。本项目利用突变体材料构建、表型鉴定、基因克隆表达、DNA-蛋白体外互作、实时荧光定量PCR、免疫亲和纯化测序、转录组测序、组学数据深度挖掘等方法，鉴定了LysR转录因子家族成员BysR在调控伯克霍尔德氏菌次生代谢物合成过程中的具体生物学功能，解析了BysR通过直接调控occidiofungin合成的途径特异性转录调控因子ambR1的表达进而正调控occidiofungin类物质合成的新机制，拓展了occidiofungin生物合成的分子信号调控网络。本项目同时首次报道了BysR在转录水平上调控pyrrolnitrin类物质的合成。转录组DNA免疫亲和纯化测序分析显示，BysR是多效调控蛋白，参与多种生物学过程相关基因的表达调控。BysR是伯克霍尔德氏菌中连接核心和次生代谢的一个重要节点，该类蛋白的发现和调控机制的研究能够拓宽我们对细菌核心代谢和次生代谢调控网络互作的理解，为我们定向选育和改造获得有生产价值的微生物菌种资源提供理论和技术支撑。此外，评估了伯克霍尔德氏菌JP2-270发酵产物在温室条件下对水稻稻瘟病和纹枯病的防治效果，为进一步研究开发微生物生物防治剂提供数据和理论支撑。