Genome sequence of the potato pathogenic fungus Alternaria solani HWC-168 reveals clues for its conidiation and virulence

Dai Zhang,Parham Haddadi,Lisong Ma,Jia-Yu He,Zhi-Hui Yang,Jie-Hua Zhu

doi:10.1186/s12866-018-1324-3

Dai Zhang, Parham Haddadi + Show 4 more

Open Access

https://doi.org/10.1186/s12866-018-1324-3

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Abstract

BackgroundAlternaria solani is a known air-born deuteromycete fungus with a polycyclic life cycle and is the causal agent of early blight that causes significant yield losses of potato worldwide. However, the molecular mechanisms underlying the conidiation and pathogenicity remain largely unknown.ResultsWe produced a high-quality genome assembly of A. solani HWC-168 that was isolated from a major potato-producing region of Northern China, which facilitated a comprehensive gene annotation, the accurate prediction of genes encoding secreted proteins and identification of conidiation-related genes. The assembled genome of A. solani HWC-168 has a genome size 32.8 Mb and encodes 10,358 predicted genes that are highly similar with related Alternaria species including Alternaria arborescens and Alternaria brassicicola. We identified conidiation-related genes in the genome of A. solani HWC-168 by searching for sporulation-related homologues identified from Aspergillus nidulans. A total of 975 secreted protein-encoding genes, which might act as virulence factors, were identified in the genome of A. solani HWC-168. The predicted secretome of A. solani HWC-168 possesses 261 carbohydrate-active enzymes (CAZy), 119 proteins containing RxLx[EDQ] motif and 27 secreted proteins unique to A. solani.ConclusionsOur findings will facilitate the identification of conidiation- and virulence-related genes in the genome of A. solani. This will permit new insights into understanding the molecular mechanisms underlying the A. solani-potato pathosystem and will add value to the global fungal genome database.

Highlights

Alternaria solani is a known air-born deuteromycete fungus with a polycyclic life cycle and is the causal agent of early blight that causes significant yield losses of potato worldwide
Genome sequencing and assembly To gain a better understanding of A. solani genome, we generated a high-quality genome sequence of A. solani HWC-168 using an Illumina HiSeq 2000 sequencing platform
These findings suggest that the presence of these species-specific secreted protein-encoding genes in the genome of A. solani HWC-168 may have originated by two possibilities: either the genome of A. solani HWC-168 possesses

Summary

Introduction

Alternaria solani is a known air-born deuteromycete fungus with a polycyclic life cycle and is the causal agent of early blight that causes significant yield losses of potato worldwide. Alternaria solani is known as the causal agent of early blight of potato and tomato. Understanding the factors influencing spore formation and identification of a wide range of secondary metabolites produced by A. solani have been the subject of extensive studies in the past many years. A. solani is capable of producing extracellular polysaccharides, carbohydrases, proteases, the new zinniol-related phytotoxins [4, 5], and other secondary metabolites during infection [6, 7]. Genetic and pathogenic variations of A. solani have

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