State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, China.
Fujian Institute for Food and Drug Quality Control, Fuzhou, China.
Curr Genet. 2019 Jun;65(3):773-783. doi: 10.1007/s00294-019-00931-9. Epub 2019 Jan 10.
The soil-borne, asexual fungus Fusarium oxysporum f.sp. lycopersici (Fol) is a causal agent of tomato wilt disease. The infection process of Fol comprises root recognition, adhesion, penetration, colonization of the root cortex and hyphal proliferation within the xylem vessels, which are under the regulation of virulence-involved transcription factors (TFs). In this study, we identified a gene, designated FolCZF1, which encodes a CH TF in Fol. The homologs of FolCzf1 are also known to affect pathogenicity in F. graminearum and Magnaporthe oryzae on wheat and rice, respectively. We learned that FolCZF1 transcript level is upregulated in conidia and early host infection stage, which led us to hypothesize that FolCzf1 is associated with early host infection in Fol. The FolCZF1 deletion mutant (ΔFolCZF1) exhibited defects in growth rate, conidiation, conidia morphology and a complete loss of virulence on tomato root. Further microscopic observation showed that ΔFolCZF1 can penetrate the root but the primary infection hypha cannot extend its colonization inside the host tissue, suggesting that FolCzf1 TF plays an important role in early infection. Fusaric acid, a secondary metabolite produced by Fusarium species, is suggested as a virulence factor in many crop diseases. We found that FolCzf1 plays a critical role in fusaric acid production by regulating the expression of fusaric acid biosynthesis genes. In summary, FolCzf1 is required for conidiation, secondary metabolism, and early host infection in Fol, and we propose that homologs of FolCzf1 are required for early parasitic growth in other plant pathogenic filamentous fungi.
土壤传播的无性真菌尖孢镰刀菌番茄专化型（Fol）是番茄枯萎病的病原体。Fol 的感染过程包括根的识别、附着、穿透、根皮层的定殖和木质部导管内的菌丝增殖，这些过程受致病相关转录因子（TFs）的调节。在本研究中，我们鉴定了一个基因 FolCZF1，它编码 Fol 中的一个 CH TF。FolCzf1 的同源物也分别影响禾谷镰刀菌和稻瘟病菌在小麦和水稻上的致病性。我们发现 FolCZF1 的转录水平在分生孢子和早期宿主感染阶段上调，这使我们假设 FolCzf1 与 Fol 中的早期宿主感染有关。FolCZF1 缺失突变体（ΔFolCZF1）在生长速度、产孢、分生孢子形态和对番茄根的完全丧失毒力方面表现出缺陷。进一步的显微镜观察表明，ΔFolCZF1 可以穿透根，但初级感染菌丝不能在宿主组织内扩展其定殖，这表明 FolCzf1 TF 在早期感染中起着重要作用。黄曲霉酸是许多作物病害中由镰刀菌属产生的一种次生代谢物，被认为是一种毒力因子。我们发现 FolCzf1 通过调节黄曲霉酸生物合成基因的表达在黄曲霉酸产生中起关键作用。总之，FolCzf1 是 Fol 中分生孢子形成、次生代谢和早期宿主感染所必需的，我们提出 FolCzf1 的同源物是其他植物病原丝状真菌早期寄生生长所必需的。
