Unique Attributes of the Laurel Wilt Fungal Pathogen, Raffaelea lauricola, as Revealed by Metabolic Profiling

Abstract

Raffaelea lauricola is the causative agent of laurel wilt, a devastating disease of lauraceous trees. R. lauricola is also an obligate nutritional symbiont of several ambrosia beetle species who act as vectors for the pathogen. Here, we sought to establish the baseline “phenome” of R. lauricola with knowledge concerning its metabolic capability, expanding our understanding of how these processes are impacted by environmental and host nutrients. Phenotypic screening using a microarray of over one thousand compounds was used to generate a detailed profile of R. lauricola substrate utilization and chemical sensitivity. These data revealed (i) relatively restricted carbon utilization, (ii) broad sulfur and phosphate utilization, and (iii) pH and osmotic sensitivities that could be rescued by specific compounds. Additional growth profiling on fatty acids revealed toxicity on C10 substrates and lower, with robust growth on C12–C18 fatty acids. Conditions for lipid droplet (LD) visualization and LD dynamics were examined using a series of lipid dyes. These data provide unique insights regarding R. lauricola metabolism and physiology, and identify distinct patterns of substrate usage and sensitivity which likely reflect important aspects of the host-microbe interface and can be exploited for the development of strategies for mitigating the spread of laurel wilt.

Risk assessment of Hass avocado and Mexican Lauraceae for attack by redbay ambrosia beetle (Coleoptera: Curculionidae: Scolytinae)

“…Susceptible trees begin to show symptoms within 2 weeks after infection and can die as early as 4 to 6 weeks post‐infection (Hughes et al, 2015a). Although the complete pathology of H. lauricola infection is still unknown, metabolic profiling is beginning to reveal the underlying mechanisms in susceptible hosts (Joseph et al, 2021). For a thorough review of the X. glabratus , H. lauricola , and laurel wilt systems, see Ploetz, Kendra, Choudhury et al (2017) and Olatinwo et al (2021).…”

Symbiotic Fungi Associated With Xyleborine Ambrosia Beetles (Coleoptera: Curculionidae: Scolytinae) and the Imperative of Global Collaboration

“…examination(Joseph et al 2021). However, effective methods for controlling the movement of X. glabratus and other vectors are very limited(Rivera et al 2020), and there are few effective treatments for trees infected with H. lauricola(Olatinwo et al 2021).…”

Selection of redox dye and inoculum conditions for the optimisation of respirometric indices in <i>Verticillium</i> and <i>Trichoderma</i>

“…For inoculum preparation, the FF inoculum fluid proposed by Biolog TM for filamentous fungi Pertile et al, 2020) and the PM3.5-8 inoculum fluid (Joseph et al, 2021) that, as previously demonstrated, are adequate for the evaluation of fungal response in microplate functional assays, were compared. In addition to the inoculum fluid and the type of indicator compound, it was necessary to test different concentrations of a nitrogen source.…”