[目的]为研究大豆/白菜轮作及大豆秸秆还田对白菜根肿病的防治机理,并为今后该种植的绿色综合防控模式提供理论基础和技术支撑,探索防治白菜根肿病新方法提供可靠思路.[方法]利用实时荧光定量PCR、土壤微生物高通量测序和温室盆栽防效测定等方法,研究大豆/白菜轮作和大豆秸秆还田处理对白菜根肿病发生和根际微生物群落的影响.[结果]大豆与白菜轮作+大豆秸秆还田处理防治白菜根肿病的相对防效高达52.59％.大豆轮作处理的白菜根际土壤样品中每克土壤所含根肿菌休眠孢子数量减少了约77％,由原来的105个/克土壤减少到104个/克土壤.与白菜连作模式相比,大豆白菜轮作后根际土壤中细菌的OTU数,Ace,Chao1和Shannon指数均显著增加,表明大豆与白菜轮作模式能够增加根际土壤细菌的多样性.白菜连作根际土壤富集假单胞菌属(Pseudomonas)、葡萄球菌属(Staphylococcus)和阿克曼菌属(Akkermansia)等,使得根际土壤微生物种群较少,而大豆与白菜轮作的根际土壤中增加了根瘤菌、鞘氨醇单胞菌等有益微生物菌的群落多样性.在真菌属水平群落结构的测序结果发现,大豆白菜轮作和大豆/白菜轮作+大豆秸秆还田的2种模式相对白菜连作模式,都显著增加了小被孢霉属(Mortierella)的丰度.进一步灌施分离来自大豆根瘤的8株根瘤菌,测定该8株根瘤菌对白菜根肿病的防效,结果显示8株根瘤菌的防治效果都高于45％,其中防治效果最好的是RG-4菌株,相对防效达到66.39％,表明大豆根瘤菌在大豆轮作中防治白菜根肿病起到重要作用.[结论]大豆/白菜轮作后显著降低了白菜根肿病的病情指数,对控制白菜根肿病具有良好的效果,该种植模式可作为防治白菜根肿病的重要栽培措施,在未来的农业生产中具有较好的应用推广前景.

Clubroot disease caused by the obligate parasite Plasmodiophora brassicae is a serious threat to cabbage production worldwide. Current clubroot control primarily relies on a fungicide, but this has a negative impact on the environment and the use of a single biocontrol agent cannot efficiently control the disease. Thus, the combined application of different biocontrol agents has been proposed as a promising alternative. In this study, we used bacterial biocontrol agents as a co-culture (inter-genus and intra-genus) and mono-culture to mitigate the clubroot disease of Chinese cabbage. We evaluated their biocontrol effect and plant growth promoter (PGP) traits in in vitro and in vivo experiments. This study revealed that the inter-genus bacterial co-culture significantly suppresses the incidence of clubroot disease and enhances plant growth compared with intra-genus and mono-culture. In pairwise interaction, we observed that Bacillus cereus BT-23 promotes the growth of Lysobacter antibioticus 13-6 (inter-genus bacterial co-culture), whereas L. capsici ZST1-2 and L. antibioticus 13-6 (intra-genus microbial co-culture) are antagonists to each other. Furthermore, a total of 5575 metabolites, 732 differentially expressed metabolites (DEMs), and 510 unique metabolites were detected through the LC-MS/MS technique in the bacterial co-culture. The number of unique metabolites in inter-genus bacterial co-culture (393 metabolites) was significantly higher than in the intra-genus bacterial co-culture (117 metabolites). Further analysis of DEMs showed that the DEMs were mainly involved in four kinds of metabolism pathways, i.e., carbohydrate metabolism, amino metabolism, nucleotide metabolism, and metabolism of cofactors and vitamins. The contents of some secondary metabolites with biocontrol activity and plant growth-promoting functions were increased in inter-genus bacterial co-culture, indicating that inter-genus bacterial co-culture has a solid potential to suppress clubroot disease. We conclude that the inter-genus bacterial interaction changes the community metabolism and improves several secondary metabolites functions with respect to disease control and PGP ability.

玉米小斑病是玉米生产中的重要病害之一,本研究利用传统植物病理学和荧光定量PCR方法,研究抗生素溶杆菌对玉米小斑病菌(Bipolaris maydis)的生防效果和作用机制,为玉米小斑病的生物防控提供理论依据.结果显示,抗生素溶杆菌13-6对玉米小斑病菌丝生长和孢子萌发具有显著抑制作用,造成菌丝顶端生长受阻、表面粗糙,部分菌丝破裂,代谢粗提物抑制孢子萌发率高达92.19％,PI荧光染色显示病原菌孢子破裂并死亡.温室叶面喷施13-6发酵液、发酵液粗提物后显著降低玉米小斑病病情指数,相对防效分别达到42.43％和68.06％.诱导抗性实验表明:13-6对玉米小斑病的诱导防效达49.57％.玉米植株体内相关抗性基因表达结果显示,在灌根处理3 d后,抗病相关基因PR1和PR5、脂氧合酶LOX、乙烯受体ETR1均被激活表达,9 d达到最大值.研究证实抗生素溶杆菌13-6对玉米小斑病具有较好的生防效果,直接喷施可减缓玉米小斑病的发生,灌根施用使植株产生诱导抗性.