Search Results (2)

Thielaviopsis paradoxa sensu lato is a soilborne fungal pathogen that causes Thielaviopsis trunk rot and heart rot in palms. The loss of structural integrity resulting from trunk rot can cause the palm trunk to collapse suddenly and poses a serious threat to life and property. Even though rudimentary knowledge about the Thielaviopsis infection process in palms is available, nothing is known about the T. paradoxa species complex in the US. The aim of this study was to characterize T. paradoxa s. lat. isolates collected from diseased palms grown in Florida. Multi-locus phylogeny using three genes, ITS, β-tubulin, and tef1-α, revealed that the isolates separate into two distinct clades with high bootstrap support. The majority of the isolates clustered with the species T. ethacetica, while two isolates formed a separate clade, distinct from T. musarum, and might represent an undescribed Thielaviopsis species. One representative isolate from each clade, when grown on three distinct media and at four different temperatures, showed differences in gross colony morphology, as well as growth rates. The T. ethacetica isolate TP5448 and the Thielaviopsis sp. isolate PLM300 grew better at opposite ends of the temperature spectrum tested in this study, i.e., 35 °C and 10 °C, respectively. In pathogenicity assays on whole plants, the T. ethacetica isolate proved to be more aggressive than Thielaviopsis sp. isolate PLM300, as it produced larger lesions when inoculated on wounded leaflets. An unequal distribution was observed for the mating-type locus of T. ethacetica, as 12 isolates carried the MAT1-1-1 allele, while the status for four isolates remained undefined. Variation in mycelial growth in response to different fungicides was also observed between the two clades. These results demonstrate the existence of two Thielaviopsis clades that can infect palms in Florida and underscore the need for targeted sampling to help uncover the diversity of Thielaviopsis species across palm-growing regions in the US. Full article

The black scorch disease of date palm caused by Thielaviopsis punctulata is a serious threat to the cultivation and productivity of date palm in Arabian Peninsula. The virulence factors that contribute to pathogenicity of T. punctulata have not been identified yet. In the present study, using bioinformatics approach, secretory proteins of T. punctulata were identified and functionally characterized. A total of 197 putative secretory proteins were identified, of which 74 were identified as enzymes for carbohydrate degradation (CAZymes), 25 were proteases, and 47 were predicted as putative effectors. Within the CAZymes, 50 cell wall-degrading enzymes, potentially to degrade cell wall components such as cellulose, hemicellulose, lignin, and pectin, were identified. Of the 47 putative effectors, 34 possessed at least one functional domain. The secretome of T. punctulata was compared to the predicted secretome of five closely related species (T. musarum, T. ethacetica, T. euricoi, T. cerberus, and T. populi) and identified species specific CAZymes and putative effector genes in T. punctulata, providing a valuable resource for the research aimed at understanding the molecular mechanism underlying the pathogenicity of T. punctulata on Date palm. Full article