“有活力但不可培养”(VBNC)状态是指细菌失去了在常规培养基上生长并形成菌落的能力，但仍然具有活性和复苏能力。VBNC状态的病原细菌复苏后能够重新形成菌落、恢复代谢活性和致病性。然而，VBNC概念提出距今已经30多年，其机制仍未得到全面的阐述。本项目在前期已经证实番茄溃疡病菌在铜离子和酸性条件诱导下进入VBNC状态，并确证可复苏的基础上，计划以番茄溃疡病菌这一重要的检疫性革兰氏阳性植物病原细菌为材料，通过转录组测序、VBNC菌体的形态变化研究、细胞壁组成分析、抗逆性和致病性测定，阐明参与VBNC状态的关键基因，并进行敲除和互补验证，全面解析番茄溃疡病菌VBNC 状态的机制。预期结果将填补国内外植物病原细菌VBNC状态机制研究的空白，拓展对革兰氏阳性植物病原细菌存活状态的认识，解析VBNC状态番茄溃疡病菌的抗逆机制及其潜在风险，为控制检疫性有害生物入侵和植物细菌病害综合防治提供新思路。

Bacteria in the viable but non-culturable (VBNC) state fail to grow on routine culture media on which they would normally grow and develop into colonies, but are alive and capable of renewed metabolic activity. The bacterial cells in VBNC state can resuscitate, return to an actively metabolizing and culturable form, and retain virulence in some adaptable conditions. However, the molecular mechanism is still unsolved after more than thirty years of VBNC state research. Clavibacter michiganensis subsp. michignensis (Cmm) is one of the most important quarantine phytopathogenic bacteria in China. As the causal agent of bacterial canker disease of tomato, its occurrence has caused substantial economic losses for seed production and fresh/processing tomato production worldwide. In previous studies, we proved that the culturable Cmm cells can be induced into VBNC state by copper and low pH condition. The VBNC-Cmm cells resuscitated and regained their culturability and pathogenicity when they were grown in tomato seedling homogenate media or inoculated on tomato seedlings. In this project, we plan to reveal the mechanism of VBNC-Cmm cells, based on the transcriptome RNA-Seq analysis, bacterial morphological characteristics observation, the cell wall peptidoglycan architecture and structure analysis, as well as the resistance and pathogenicity tests of VBNC-Cmm cells, and disclose the key genes involved in VBNC state and confirm their functions by gene knockout and complementation technology. It is the first study on VBNC state for Gram-positive phytopathogenic bacteria, as well as the first VBNC study on phytopathogenic bacteria in China. The expected results of this project will contribute to bacterial biology and resistance mechanism, and provide novel viewpoints for detection of plant pathogenic bacteria, invasion of quarantine pests and management of crop diseases.