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.
Highlights
Laurel wilt is a lethal disease of susceptible plants in the family Lauraceae, a group containing over 600 species including avocado, red bay, swamp bay, and sassafras [1]
This disease is endemic in the southeastern United States, where it is caused by the invasive ambrosia fungus, Raffaelea lauricola (Ascomycota: Ophiostomatales)
Knowledge concerning the metabolic capability of a pathogen can aid in our understanding of how the pathogenic process may be impacted by environmental and host nutrients that can be made available and used by the invading fungus
Summary
Laurel wilt is a lethal disease of susceptible plants in the family Lauraceae, a group containing over 600 species including avocado, red bay, swamp bay, and sassafras [1]. Amongst an additional 282 peptide nitrogen sources tested, R. lauricola showed little to no growth on 114 (40%) of these, including val-tyr-val, pro-hyp (hydroxy proline), and asp-trp (Supplemental Figure S3). An additional 94 different nutrient supplements were tested as potential growth substrates, and R. lauricola showed little to no growth on 81 (86%) of these including L-proline, spermidine, and L-ornithine (Supplemental Figure S2). Among the 120 chemicals tested in chemical sensitivity assays, R. lauricola showed little to no growth on 31 (26%) (Figure 4) These chemicals included sodium azide, sodium cyanate, and zaragozic acid A. Chyomphpaaerinsoo-ns ticbeeatbwle.enCNomilepaRreisdoannsdbBetOwDeIePnY-NstialeinRededsaamnpdleBsOwDitIhPiYn-csotarirneesdposnadminpgletsrewatimtheint cgorroruep- s sproenvdeainlegd gtreenaetmraellnyt cogmropuaprsablreevLeDaleddistrgiebnuetrioanllyancdosmizpea/rsahbalepe;LhDowdeisvterri,biuntitohne lanudric sizaec/isdh-gaproew; hnoswaemvperle, sin, dtihffeulsaeuflriucoarceisdc-egnrocewgnasvaemwpaleyst,odpifufunscetafltueosrpeostcsenocfeflguaovreswceanycetoat pulantcetrateimspeoptsoionftfsluuosrinesgceNnicle aRteldat,ebrutitmneotpowinitths uBsOinDgIPNYi,lesuRgegde, sbtuintgnotht awt itheBtOwDoIPdYy,es sumggaeyshtianvgethslaitgthhtelytwdioffdeyreenstmliapyidhavffiensiltiigehstalynditfhfeursenmt aliypipdroafvfidneitiueseafnudl ctohmuspmleamyepnrtoa-ry viidnefoursmefautilocnomonpliepmidendtraorpyleint fpohrmysaiotiloongyonwlhipenidudsreodpilnetppahraylsleiol.logy when used in parallel
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