The Genome of Banana Leaf Blight Pathogen Fusarium sacchari str. FS66 Harbors Widespread Gene Transfer From Fusarium oxysporum.

Yiping Cui,Xia Chen,Bo Wu,Aitian Peng,Xiaobing Song

doi:10.3389/fpls.2021.629859

Abstract

Fusarium species have been identified as pathogens causing many different plant diseases, and here we report an emerging banana leaf blight (BLB) caused by F. sacchari (Fs) discovered in Guangdong, China. From the symptomatic tissues collected in the field, a fungal isolate was obtained, which induced similar symptoms on healthy banana seedlings after inoculation. Koch’s postulates were fulfilled after the re-isolation of the pathogen. Phylogenetic analysis on two gene segments and the whole genome sequence identified the pathogen belonging to Fs and named as Fs str. FS66. A 45.74 Mb genome of FS66 was acquired through de novo assembly using long-read sequencing data, and its contig N50 (1.97 Mb) is more than 10-fold larger than the previously available genome in the species. Based on transcriptome sequencing and ab initio gene annotation, a total of 14,486 protein-encoding genes and 418 non-coding RNAs were predicted. A total of 48 metabolite biosynthetic gene clusters including the fusaric acid biosynthesis gene cluster were predicted in silico in the FS66 genome. Comparison between FS66 and other 11 Fusarium genomes identified tens to hundreds of genes specifically gained and lost in FS66, including some previously correlated with Fusarium pathogenicity. The FS66 genome also harbors widespread gene transfer on the core chromosomes putatively from F. oxysporum species complex (FOSC), including 30 involved in Fusarium pathogenicity/virulence. This study not only reports the BLB caused by Fs, but also provides important information and clues for further understanding of the genome evolution among pathogenic Fusarium species.

Highlights

Bananas (Musa spp.) are one of the most important crops in the world that has been widely planted as staple food or fruit in many tropical and subtropical regions
We reported the banana leaf blight (BLB) disease caused by Fusarium sacchari (Fs) str
When the best BLASTN hit segment in a genome is longer than 500 bp and shares >50% nucleotide similarity with the query FS66 segment, it was identified as an ortholog of the query

Summary

Introduction

Bananas (Musa spp.) are one of the most important crops in the world that has been widely planted as staple food or fruit in many tropical and subtropical regions. The genus Fusarium includes more than 20 monophyletic species complexes and several monotypic lineages involving many destructive plant pathogens (O’Donnell et al, 2015). The pathogen Fusarium sacchari (Fs) of the reported banana leaf blight (BLB) disease belongs to the Fusarium fujikuroi species complex (FFSC) which includes approximately 50 species (O’Donnell et al, 2015). FFSC is phylogenetically close to Fusarium oxysporum species complex (FOSC) which includes Foc (Maryani et al, 2019). Except for Foc and Fs, at least seven other Fusarium species have been linked to distinct banana diseases (Jones, 1997; Du et al, 2017). The large number of pathogenic Fusarium species and frequently identified new pathogenic strains toward bananas suggest that many Fusarium species have the potential to develop pathogenicity toward bananas

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