Chung Eu Jin, Hossain Mohammad Tofajjal, Khan Ajmal, Kim Kyung Hyun, Jeon Che Ok, Chung Young Ryun
Division of Applied Life Science (BK21 Plus), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Korea.
Department of Life Science, Chung-Ang University, Seoul 156-756, Korea.
Plant Pathol J. 2015 Jun;31(2):152-64. doi: 10.5423/PPJ.OA.12.2014.0136. Epub 2015 Jun 30.
Biological control of major rice diseases has been attempted in several rice-growing countries in Asia during the last few decades and its application using antagonistic bacteria has proved to be somewhat successful for controlling various fungal diseases in field trials. Two novel endophytic Bacillus species, designated strains YC7007 and YC7010(T), with anti-microbial, plant growth-promoting, and systemic resistance-inducing activities were isolated from the roots of rice in paddy fields at Jinju, Korea, and their multifunctional activities were analyzed. Strain YC7007 inhibited mycelial growth of major rice fungal pathogens strongly in vitro. Bacterial blight and panicle blight caused by Xanthomonas oryzae pv. oryzae (KACC 10208) and Burkholderia glumae (KACC 44022), respectively, were also suppressed effectively by drenching a bacterial suspension (10(7) cfu/ml) of strain YC7007 on the rhizosphere of rice. Additionally, strain YC7007 promoted the growth of rice seedlings with higher germination rates and more tillers than the untreated control. The taxonomic position of the strains was also investigated. Phylogenetic analyses based on 16S rRNA gene sequences indicated that both strains belong to the genus Bacillus, with high similarity to the closely related strains, Bacillus siamensis KACC 15859(T) (99.67%), Bacillus methylotrophicus KACC 13105(T) (99.65%), Bacillus amyloliquefaciens subsp. plantarum KACC 17177(T) (99.60%), and Bacillus tequilensis KACC 15944(T) (99.45%). The DNA-DNA relatedness value between strain YC7010(T) and the most closely related strain, B. siamensis KACC 15859(T) was 50.4±3.5%, but it was 91.5±11.0% between two strains YC7007 and YC7010(T), indicating the same species. The major fatty acids of two strains were anteiso-C15:0 and iso C15:0. Both strains contained MK-7 as a major respiratory quinone system. The G+C contents of the genomic DNA of two strains were 50.5 mol% and 51.2 mol%, respectively. Based on these polyphasic studies, the two strains YC7007 and YC7010(T) represent novel species of the genus Bacillus, for which the name Bacillus oryzicola sp. nov. is proposed. The type strain is YC7010(T) (= KACC 18228(T)). Taken together, our findings suggest that novel endophytic Bacillus strains can be used for the biological control of rice diseases.
在过去几十年里，亚洲的几个水稻种植国家已尝试对主要水稻病害进行生物防治，并且在田间试验中，利用拮抗细菌进行生物防治已被证明在控制各种真菌病害方面取得了一定成功。从韩国晋州稻田的水稻根部分离出了两种具有抗菌、促进植物生长和诱导系统抗性活性的新型内生芽孢杆菌，分别命名为菌株YC7007和YC7010(T)，并对它们的多功能活性进行了分析。菌株YC7007在体外能强烈抑制主要水稻真菌病原体的菌丝生长。通过在水稻根际浇灌菌株YC7007的细菌悬液（10(7) cfu/ml），也有效抑制了分别由水稻黄单胞菌稻瘟致病变种（KACC 10208）和颖枯伯克霍尔德菌（KACC 44022）引起的白叶枯病和穗枯病。此外，菌株YC7007促进了水稻幼苗的生长，其发芽率和分蘖数均高于未处理的对照。还对这些菌株的分类地位进行了研究。基于16S rRNA基因序列的系统发育分析表明，这两种菌株都属于芽孢杆菌属，与密切相关的菌株暹罗芽孢杆菌KACC 15859(T)（99.67%）、甲基营养型芽孢杆菌KACC 13105(T)（99.65%）、解淀粉芽孢杆菌植物亚种KACC 17177(T)（99.60%）和特基拉芽孢杆菌KACC 15944(T)（99.45%）具有高度相似性。菌株YC7010(T)与最密切相关的菌株暹罗芽孢杆菌KACC 15859(T)之间的DNA-DNA相关性值为50.4±3.5%，但在菌株YC7007和YC7010(T)之间为91.5±11.0%，表明它们为同一物种。两种菌株的主要脂肪酸为anteiso-C15:0和iso C15:0。两种菌株都含有MK-7作为主要呼吸醌系统。两种菌株基因组DNA的G+C含量分别为50.5 mol%和51.2 mol%。基于这些多相研究，菌株YC7007和YC7010(T)代表芽孢杆菌属的新物种，为此提出新名称芽孢杆菌稻栖菌（Bacillus oryzicola sp. nov.）。模式菌株为YC7010(T)（= KACC 18228(T)）。综上所述，我们的研究结果表明，新型内生芽孢杆菌菌株可用于水稻病害的生物防治。
