Wu Qianhua, Wang Bozhen, Shen Xi, Shen Danyu, Wang Bingxin, Guo Qinggang, Li Tao, Shao Xiaolong, Qian Guoliang
College of Plant Protection, Laboratory of Plant Immunity, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, No.1 Weigang, Nanjing, Jiangsu, 210095, People's Republic of China.
Institute of Plant Protection, Hebei Academy of Agricultural and Forestry Sciences, Integrated Pest Management Center of Hebei Province, Key Laboratory of IPM on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs of China, Baoding, 071000, People's Republic of China.
Stress Biol. 2021 Dec 16;1(1):19. doi: 10.1007/s44154-021-00018-x.
Plant growth-promoting rhizobacteria (PGPR) contain various biocontrol bacteria with broad-spectrum antimicrobial activity, and their single species has been extensively applied to control crop diseases. The development of complex biocontrol community by mixing two or more PGPR members together is a promising strategy to enlarge the efficacy and scope of biocontrol. However, an effective method to assess the natural compatibility of PGPR members has not yet been established to date. Here, we developed such a tool by using the bacterial contact-dependent antibacterial activity (CDAA) as a probe. We showed that the CDAA events are common in two-species interactions in the four selected representative PGPRs, represented by the incompatible interaction of Lysobacter enzymogenes strain OH11 (OH11) and Lysobacter antibioticus strain OH13 (OH13). We further showed that the CDAA between OH11 and OH13 is jointly controlled by a contact-dependent killing device, called the type IV secretion system (T4SS). By deleting the respective T4SS synthesis genes, the T4SS in both strains was co-inactivated and this step unlocked their natural CDAA, resulting in an engineered, compatible mutant alliance that co-displayed antibacterial and antifungal activity. Therefore, this study reveals that releasing bacterial CDAA is effective to rationally engineer the biocontrol community.
植物促生根际细菌（PGPR）包含各种具有广谱抗菌活性的生防细菌，其单一菌种已被广泛应用于防治作物病害。将两种或更多PGPR成员混合在一起构建复杂的生防菌群是扩大生防效果和范围的一种有前景的策略。然而，迄今为止尚未建立一种有效的方法来评估PGPR成员之间的自然相容性。在此，我们通过使用细菌接触依赖性抗菌活性（CDAA）作为探针开发了这样一种工具。我们发现，在四种选定的代表性PGPR的两菌种相互作用中，CDAA事件很常见，以食纤维溶杆菌菌株OH11（OH11）和抗生溶杆菌菌株OH13（OH13）的不相容相互作用为代表。我们进一步表明，OH11和OH13之间的CDAA由一种称为IV型分泌系统（T4SS）的接触依赖性杀伤装置共同控制。通过删除各自的T4SS合成基因，两菌株中的T4SS被共同灭活，这一步骤开启了它们的天然CDAA，产生了一种经工程改造的、相容性突变体联盟，该联盟共同展现出抗菌和抗真菌活性。因此，本研究表明，释放细菌CDAA对于合理构建生防菌群是有效的。
