松树是重要的经济树种,但是松树枯萎病(PWD)严重威胁着松树的生存。松材线虫引起的PWD是世界范围内的一种主要检疫疾病,会造成巨大的经济损失。然而,需要更多关于其分子发病机制的信息,导致缺乏有效的预防和治疗措施。近年来,效应因子已成为探索病原体分子致病机制的热点。这里,我们确定了一个特定的效应器,BxNMP1,来自B。原位杂交实验表明,BxNMP1在背腺细胞和肠细胞中特异性表达,RT-qPCR实验显示BxNMP1在感染早期表达上调。BxNMP1在无毒菌株中的序列不同,当BxNMP1沉默的木偶双歧杆菌被接种到桑贝吉幼苗中时,疾病严重程度显著降低。我们证明了BxNMP1与Thaumatin样蛋白PtTLP-L2相互作用。此外,我们发现β-1,3-葡聚糖酶PtGLU与PtTLP-L2相互作用。因此,我们假设BxNMP1可能通过PtTLP-L2作为中间介体与PtGLU间接相互作用.这两个目标都可以对感染做出反应,PtTLP-L2可以增强松树的抵抗力。此外,当BxNMP1沉默或添加PtTLP-L2重组蛋白时,我们检测到接种木偶双歧杆菌的桑柏幼苗中水杨酸含量增加。总之,我们确定了PWN的一个关键毒力效应子,BxNMP1.它正向调节木线菌的致病性,并直接与PtTLP-L2相互作用,间接与PtGLU相互作用。它还抑制两个靶标和宿主水杨酸途径的表达。本研究为防治PWD和抗病育种提供了理论指导和实践依据。
Pinus is an important economic tree species, but pine wilt disease (PWD) seriously threatens the survival of pine trees. PWD caused by Bursaphelenchus xylophilus is a major quarantine disease worldwide that causes significant economic losses. However, more information about its molecular pathogenesis is needed, resulting in a lack of effective prevention and treatment measures. In recent years, effectors have become a hot topic in exploring the molecular pathogenic mechanism of pathogens. Here, we identified a specific
effector, BxNMP1, from B. xylophilus. In situ hybridization experiments revealed that BxNMP1 was specifically expressed in dorsal gland cells and intestinal cells, and RT-qPCR experiments revealed that BxNMP1 was upregulated in the early stage of infection. The sequence of BxNMP1 was different in the avirulent strain, and when BxNMP1-silenced B. xylophilus was inoculated into P. thunbergii seedlings, the disease severity significantly decreased. We demonstrated that BxNMP1 interacted with the thaumatin-like protein PtTLP-L2 in P. thunbergii. Additionally, we found that the β-1,3-glucanase PtGLU interacted with PtTLP-L2. Therefore, we hypothesized that BxNMP1 might indirectly interact with PtGLU through PtTLP-L2 as an intermediate mediator. Both targets can respond to infection, and PtTLP-L2 can enhance the resistance of pine trees. Moreover, we detected increased salicylic acid contents in P. thunbergii seedlings inoculated with B. xylophilus when BxNMP1 was silenced or when the PtTLP-L2 recombinant protein was added. In summary, we identified a key virulence
effector of PWNs, BxNMP1. It positively regulates the pathogenicity of B. xylophilus and interacts directly with PtTLP-L2 and indirectly with PtGLU. It also inhibits the expression of two targets and the host salicylic acid pathway. This study provides theoretical guidance and a practical basis for controlling PWD and breeding for disease resistance.