Elfstrand, M. | Search bioRxiv

bioRxiv2024

Genome sequence resources from three isolates of the apple canker pathogen Neonectria ditissima infecting forest trees.

Neonectria ditissima is a generalist ascomycete plant pathogen causing canker diseases on a variety of hardwood tree species and can cross-infect many of them. The fungus enters the plants through wounds throughout the year. N. ditissima is considered a major threat to apple production responsible for the fruit tree canker disease which damages trees and causes rotting of fruits in storage. Nearby forests and shelter belts can serve as source of inoculum for well-managed apple orchards. Thus, knowledge about the N. ditissima isolates infecting different host species is essential for designing integrated pest management strategies. Here, we describe the genomes of three N. ditissima isolates, Nd_iso34, Nd_iso35, and Nd_iso36, infecting European beech, American tulip tree, and American beech, respectively. We obtained genome assemblies of ca. 45 megabases for all isolates, covering 94% of the N. ditissima reference annotation, and 97% of the universal single-copy orthologs (BUSCOs). We conclude that these genome assemblies are a highly relevant resource considering the scarcity of genomic data available for N. ditissima.

genomics↗

bioRxiv2020

Annulohypoxylon sp. strain MUS1, an Endophyte isolated from Taxus wallichiana Zucc. produces Taxol and Other Bioactive Metabolites

Endophytes are microbial colonizers that reside in plants by symbiotic association produces several biological classes of natural products. The current study focuses on the isolation and characterization of bioactive compounds produced by endophytic fungi isolated from the Himalayan yew (Taxus wallichiana) collected from the Mustang district of Nepal. The plant materials were collected from the Lower-Mustang region in the month of October 2016 and the endophytic fungi were isolated on artificial media from inner tissues of bark and needles. Antimicrobial and antioxidant activity, along with total phenolic- and flavonoid-content assays, were used in the evaluation of bioactivity of the fermented crude extracts along with the in vitro ability of the endophytes to produce the anticancer compound Taxol was analyzed. A total of 16 fungal morphotypes were obtained from asymptomatic inner tissues of the bark and needles of T. wallichiana. Among the 16 isolates, the ethyl acetate (EA) fraction of isolate MUS1, showed antibacterial and antifungal activity against all test-pathogens used, with significant inhibition against Pseudomonas aeruginosa ATCC 27853 (MIC: 250 {micro}g/ml) and the pathogenic yeast, Candida albicans (MIC: 125 {micro}g/ml). Antioxidant activity was also evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH). At a concentration of 100 {micro}g/ml, the % radical scavenging activity was 83.15{+/-}0.40, 81.62{+/-}0.11, and 62.36{+/-}0.29, for ascorbic acid, butylated hydroxytoluene (BHT) and the EA fraction of MUS1, respectively. The DPPH-IC50 value for the EA fraction was 81.52 {micro}g/ml, compared to BHT (62.87 {micro}g/ml) and ascorbic acid (56.15 {micro}g/ml). The total phenolic and flavonoid content in the EA fraction were 16.90{+/-}0.075 {micro}g gallic acid equivalent (GAE) and 11.59{+/-}0.148 {micro}g rutin equivalent (RE), per mg of dry crude extract, respectively. Isolate MUS1, identified as an Annulohypoxylon sp. by ITS sequencing, also produced Taxol (282.05 {micro}g/L) as shown by TLC and HPLC analysis. Having the ability to produce antimicrobial and antioxidant compounds, as well as the anticancer compound Taxol, makes Annulohypoxylon sp. strain MUS1, a promising candidate for further study given that naturally occurring bioactive compounds are of great interest to the pharmacological, food and cosmetic industries.

microbiology↗