UDP-glucose pyrophosphorylase (UGP, EC 2.7.7.9) is an essential enzyme involved in carbohydrate metabolism. In Saccharomyces cerevisiae and other fungi, the UGP gene is indispensable for normal cell development, polysaccharide synthesis, and stress response. However, the function of the UGP homolog in plant pathogenic fungi has been rarely explored during pathogenesis. In this study, we characterize a UGP homolog named VdUGP from Verticillium dahliae, a soil-borne fungus that causes plant vascular wilt. In comparison with wild-type strain V07DF2 and complementation strains, the VdUGP knocked down mutant 24C9 exhibited sensitivity to sodium dodecyl sulfate (perturbing membrane integrity) and high sodium chloride concentration (high osmotic pressure stress). More than 25 % of the conidia of the mutant developed into short and swollen hypha and formed hyperbranching and compact colonies. The mutant exhibited decreased virulence on cotton and tobacco seedlings. Further investigation determined that the germination of the mutant spores was significantly delayed compared with the wild-type strain on the host roots. RNA-seq analysis revealed that a considerable number of genes encoding secreted proteins and carbohydrate-active enzymes were significantly downregulated in the mutant at an early stage of infection compared with those of the wild-type strain. RNA-seq data indicated that mutation affected many Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways both in the pathogen and in the inoculated plants at the infection stage. These alterations of the mutant in cultural phenotypes, virulence, and gene expression profiles clearly indicated that VdUGP played important roles in fungal cell morphogenesis, stress responses, and host infection.

中文翻译：

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来自大丽轮枝菌的 UDP-葡萄糖焦磷酸化酶参与细胞形态发生、应激反应和宿主感染

UDP-葡萄糖焦磷酸化酶（UGP，EC 2.7.7.9）是参与碳水化合物代谢的必需酶。在酿酒酵母和其他真菌中，UGP 基因对于正常细胞发育、多糖合成和应激反应是必不可少的。然而，在植物病原真菌中 UGP 同源物的功能在发病过程中很少被探索。在这项研究中，我们表征了来自大丽轮枝菌的一种名为 VdUGP 的 UGP 同源物，大丽轮枝菌是一种导致植物维管枯萎的土传真菌。与野生型菌株 V07DF2 和互补菌株相比，VdUGP 敲低突变体 24C9 表现出对十二烷基硫酸钠（扰乱膜完整性）和高氯化钠浓度（高渗透压应力）的敏感性。超过 25% 的突变体分生孢子发育成短而肿胀的菌丝，并形成超分枝和紧凑的菌落。该突变体对棉花和烟草幼苗表现出降低的毒力。进一步研究确定，与寄主根上的野生型菌株相比，突变孢子的萌发显着延迟。RNA-seq 分析显示，与野生型菌株相比，在感染早期的突变体中，相当多的编码分泌蛋白和碳水化合物活性酶的基因显着下调。RNA-seq数据表明，突变影响了病原体和感染阶段接种植物中的许多京都基因和基因组百科全书（KEGG）途径。这些突变体在培养表型、毒力、