Genomic analysis of Alternaria alternata, the causal agent of black spot disease in Korla fragrant pears (Pyrus sinkiangensis Yü) in China

Alternaria alternata is a pathogenic fungus that adversely affects fruit crops and causes substantial economic loss. A specific strain of A. alternata (A923) was successfully isolated and identified from Korla fragrant pears ( Pyrus sinkiangensis Yü). The ability of this strain to induce black spot disease in pears was verified. A combination of Illumina and PacBio Sequel sequencing was used to obtain the genome sequence for understanding the A923 strain. The assembly process revealed that the genome consists of 36 070 468 bp (36.07 Mb). Consequently, the analysis primarily focused on the genes associated with pathogenicity. These findings revealed the presence of 794 CAZymes, including 119 glycosyltransferases, 26 polysaccharide lyases, 153 carbohydrate esterases, 161 auxiliary activities, 19 carbohydrate-binding modules, and 316 glycoside hydrolases. A database of fungal virulence factors identified 1258 genes in strain A923. CUTI_ALTBR, a member of the cutinase family, is responsible for catalyzing the hydrolysis of cutin, a polyester that forms the structure of the plant cuticle. This enzymatic activity allows the pathogenic fungi to breach the cuticular barrier during the initial stages of infection. Cytochrome P450 family analysis successfully annotated 11 458 genes (97.63%). The results obtained in this study provide a useful resource for further investigation of this pathogen and its pathosystem.