Valley Laboratory, Connecticut Agricultural Experiment Station, Windsor, CT, USA.
Department of Biomolecular Chemistry, University of Wisconsin-Madison, School of Medicine and Public Health, Madison, WI, USA.
Commun Biol. 2024 Mar 21;7(1):348. doi: 10.1038/s42003-024-06034-7.
Secreted laccases are important enzymes on a broad ecological scale for their role in mediating plant-microbe interactions, but within ascomycete fungi these enzymes have been primarily associated with melanin biosynthesis. In this study, a putatively secreted laccase, Sslac2, was characterized from the broad-host-range plant pathogen Sclerotinia sclerotiorum, which is largely unpigmented and is not dependent on melanogenesis for plant infection. Gene knockouts of Sslac2 demonstrate wide ranging developmental phenotypes and are functionally non-pathogenic. These mutants also displayed indiscriminate growth behaviors and enhanced biomass formation, seemingly as a result of their inability to respond to canonical environmental growth cues, a phenomenon further confirmed through chemical stress, physiological, and transcriptomic analyses. Transmission and scanning electron microscopy demonstrate apparent differences in extracellular matrix structure between WT and mutant strains that likely explain the inability of the mutants to respond to their environment. Targeting Sslac2 using host-induced gene silencing significantly improved resistance to S. sclerotiorum, suggesting that fungal laccases could be a valuable target of disease control. Collectively, we identified a laccase critical to the development and virulence of the broad-host-range pathogen S. sclerotiorum and propose a potentially novel role for fungal laccases in modulating environmental sensing.
分泌漆酶在介导植物-微生物相互作用方面具有广泛的生态意义，是重要的酶，但在子囊菌真菌中，这些酶主要与黑色素生物合成有关。在这项研究中，从广谱植物病原菌核盘菌中鉴定出一种假定的分泌漆酶Sslac2，该菌基本无色，并且不依赖黑色素生成进行植物感染。Sslac2 的基因敲除显示出广泛的发育表型，并且在功能上是非致病性的。这些突变体还表现出不分青红皂白的生长行为和增强的生物量形成，似乎是由于它们无法响应典型的环境生长线索，这一现象通过化学应激、生理和转录组分析进一步得到证实。透射和扫描电子显微镜显示 WT 和突变菌株之间细胞外基质结构存在明显差异，这可能解释了突变体无法响应其环境的原因。使用宿主诱导基因沉默靶向 Sslac2 显著提高了对核盘菌的抗性，这表明真菌漆酶可能是疾病控制的一个有价值的靶点。总的来说，我们鉴定出一种对广谱病原菌核盘菌的发育和毒力至关重要的漆酶，并提出真菌漆酶在调节环境感应方面的潜在新作用。
