Bursaphelenchus xylophilus is an economically important pathogen that has caused serious damage to pine forests. Fatty acid and retinol-binding proteins (FARs) are nematode-specific proteins. One FAR gene, Bx-FAR-1, was identified from the transcriptome of B. xylophilus as a putative effector. It was upregulated in both highly and weakly virulent isolates in early infection stages. Transient expression assays showed that Bx-FAR-1 inhibited BAX- and INF1-induced cell death in Nicotiana benthamiana when secreted into the intracellular site. Bx-FAR-1 was expressed in the glandular tissues, intestines, and seminal vesicles of nematodes by in situ hybridization. Silencing Bx-FAR-1 via in vitro RNA interference attenuated the reproductive ability and pathogenicity of B. xylophilus as well as increased the expression of the pathogenesis-related gene 6 and JA biosynthesis gene LOX-5 (lipoxygenase-5) in pine trees. These results suggest that Bx-FAR-1 suppresses the plant immune response in the N. benthamiana intracellular site and may contribute to the pathogenicity of B. xylophilus in the early infection stages.

松材线虫是一种经济上重要的病原体，已对松树林造成了严重破坏。脂肪酸和视黄醇结合蛋白（FARs）是线虫特异性蛋白。从木糖双歧杆菌的转录组中鉴定出一种FAR基因Bx-FAR-1作为推定的效应子。在早期感染阶段，高毒力和弱毒力的分离株均被上调。瞬时表达分析表明Bx-FAR-1抑制了本氏烟草对BAX和INF1诱导的细胞死亡当分泌到细胞内部位时。通过原位杂交，Bx-FAR-1在线虫的腺组织，肠和精囊中表达。通过体外RNA干扰使Bx-FAR-1沉默会减弱木糖双歧杆菌的繁殖能力和致病性，并增加发病机理相关基因6和JA生物合成基因LOX-5（脂加氧酶-5）在松树中的表达。这些结果表明，Bx-FAR-1抑制了本氏烟草内细胞部位的植物免疫反应，并可能在感染的早期阶段导致了嗜木芽孢杆菌的致病性。