Two novel Fusarium species that cause canker disease of prickly ash (Zanthoxylum bungeanum) in northern China form a novel clade with Fusarium torreyae

Abstract

Canker disease of prickly ash (Zanthoxylum bungeanum) has caused a decline in the production of this economically important spice in northern China in the past 25 y. To identify the etiological agent, 38 fungal isolates were recovered from symptomatic tissues from trees in five provinces in China. These isolates were identified by conducting BLASTN queries of NCBI GenBank and phylogenetic analyses of DNA sequence data from the nuclear ribosomal internal transcribed spacer region (ITS rDNA), a portion of the translation elongation factor 1-α (TEF1) gene, and genes encoding RNA polymerase II largest (RPB1) and second largest (RPB2) subunits. Results of these analyses suggested that 30/38 isolates belonged to two novel fusaria most closely related to the Florida torreya (Torreya taxifolia Arn.) pathogen, Fusarium torreyae in Florida and Georgia. These three canker-inducing tree pathogens form a novel clade within Fusarium here designated the F. torreyae species complex (FTOSC). BLASTN queries of GenBank also revealed that 5/38 isolates recovered from cankers represented an undescribed phylogenetic species within the F. solani species complex (FSSC) designated FSSC 6. Stem inoculations of three fusaria on Z. bungeanum resulted in consistent canker symptoms from which these three fusaria were recovered. The two novel fusaria, however, induced significantly larger lesions than FSSC 6. Herein, the two novel prickly ash pathogens are formally described as F. zanthoxyli and F. continuum.

PCR Multiplexes DiscriminateFusariumSymbionts of InvasiveEuwallaceaAmbrosia Beetles that Inflict Damage on Numerous Tree Species Throughout the United States

“…and cultivated prickly ash (Zanthoxylum bungeanum Maxim.) in China Smith et al 2011;Zhou et al 2016). Certain members of the FSSC have also been implicated as causal agents in the disease complex thousand cankers disease of walnut (Juglans spp.)…”

Fusarium incarnatum-equiseti complex from China

“…The genus Fusarium is represented by 17 species complexes on the basis of multi-locus phylogenetic analyses (Laurence et al 2011, Aoki et al 2013, O'Donnell et al 2013, Zhou et al 2016, Sandoval-Denis et al 2018a. The Fusarium incarnatumequiseti species complex (FIESC) includes only a few formally described species characterised by the typically dorsiventral curvature of macroconidia and abundant chlamydospores, which range from being single or in chains or clumps, except for F. scirpi which lacks microconidia (Booth 1971, Leslie & Summerell 2006.…”

Detection method for Fusarium torreyae the canker pathogen of the critically endangered Florida torreya, Torreya taxifolia

“…(2016) as guides, the genes encoding RNA polymerase II largest (RPB1) and second largest (RPB2) subunits were selected for development of a F. torreyae ‐specific PCR assay. The two recent studies (Aoki et al., 2013 and Zhou et al., 2016) were used to identify related taxa and sequences, supplemented with others as needed, then retrieved from GenBank (http://www.ncbi.nlm.nih.gov/genbank) and aligned in Geneious 9.1.8 (https://www.geneious.com/). Areas that were unique to F. torreyae were identified, and primers were designed for these locations.…”

“…The phylogenetic study by Zhou et al. (2016) was used to select taxa for the specificity test, which are listed in Table 1. The two closest relatives of F. torreyae , F. zanthoxyii and F. continuum , along with one taxon from each of the related species complexes and F. aywerte , representing a small but related clade, were chosen.…”