| 摘要: |
| 为探明芽孢杆菌处理对柑桔苗木黄龙病的抑制效果，本研究对复合菌剂进行分离得到单菌落，对No.4菌株进行细菌纯培养鉴定，通过序列测定确定其分类地位，并采用固体发酵方法制备菌剂，用该菌剂对3个品种的盆栽苗木进行灌根处理。结果表明:No.4菌株属芽孢杆菌属，革兰氏染色呈阳性；通过16S rDNA和recA基因测序分析，证明该No.4菌株与贝莱斯芽孢杆菌同源性达93%；该菌剂灌根21次时，‘沃柑’和‘沙糖橘’黄龙病阳性率由处理前的100%分别降低至50%和75%，而对照样品的阳性率均保持不变；No.4菌剂处理能促进‘沃柑’、‘沙糖橘’和南丰蜜橘3个品种的新生根系增多，褐变根系减少；扫描电镜和石蜡切片观察表明:南丰蜜橘韧皮部杆菌造成根系褐变，染病植株根系的表皮细胞易产生木栓化，表皮细胞上翘，内皮层产生空洞，结构破坏；No.4菌剂处理后，病原诱导启动子GST1及转录因子WRKY22和WRKY24基因的mRNA相对表达量提高。可见，No.4菌剂对柑桔苗木黄龙病有一定程度的抑制效果，对褐变根系有明显的缓解作用。 |
| 关键词: 贝莱斯芽孢杆菌 韧皮部杆菌 实时定量 根系褐变 抗性基因 |
| DOI：10.11841/j.issn.1007-4333.2021.08.08 |
| 投稿时间：2021-01-12 |
| 基金项目:国家重点研发计划(2019YFD1001802,2018YFD0201505)；国家自然科学基金项目(31872064) |
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| Inhibitory effect of Bacillus treatment on citrus Huanglongbing disease in nursery growth plants |
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HU Dangzhen,XU Yuanyuan,YU Mengyi,JIANG Ling
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| (College of Horticulture and Forestry/Key Laboratory of Plant Biology of Ministry of Education/The Countries Indoor Conservation Center ofVirus-Free Germplasm Resources of Fruit Trees/Key Laboratory of Horticultural Crop Biology and Germplasm Creation inCentral China of Ministry of Agriculture and Rural Affairs, Huazhong Agricultural University, Wuhan 430070, China) |
| Abstract: |
| To investigate the effect of Bacillus treatment on Huanglongbing-infected citrus nusery-growth plants, a single colony of Bacillus was isolated and purified from the compound bacterial agent. Bacterial pure culture identification tests and sequencing were performed to determine the classification status of strain No. 4, then, No. 4 bacterial agent was prepared by solid-state fermentation. The plants of three citrus varieties were irrigated with it. The results showed that No. 4 strain was gram positive stain and it belongs to the genus Bacillus, and it shared 93% homologous with Bacillus velezensis via the sequence alignment of 16S rDNA and recA genes; Irrigation the citrus plants with B. velezensis No. 4 bacterial agent for 21 times, the positive rate of HLB decreased from 100% to 50% and 75% in Citrus reticulata Blanco ‘orah' and C. reticulata cv. ‘shiyue ju' separately, the positive rate of the control samples remained unchanged. No. 4 bacterial agent could promote the root system developed well and the browning root system decreased in ‘orah', ‘shiyue ju', and ‘nanfengmiju' obviously; Microstructural observation in C. reticulata cv. Kinokuni indicated that the root system browning caused by Candidatus Liberobacter was serious, the epidermal cells of browning root showed corkization, turn upward and structural damaged by scanning electron microscopy and paraffin section; The analysis of relative expression levels of resistance-related genes indicated that the relative expression levels of mRNA of pathogen-induced promoter GST1 and transcription factors WRKY22 and WRKY24 genes were higher than those of the control group. Therefore, No. 4 Bacillus agent had inhibition effect to a certain extent on citrus Huanglongbing disease, and it had obvious relieving effect on browning root. |
| Key words: Bacillus velezensis Candidatus Liberobacter roots Browning Resistance gene |
