Abstract:

Walnut blight is the most serious bacterial disease in walnut production. Chemical control is easy to cause pollution and resistance problems, and green and efficient biocontrol resources are urgently needed. As an important biocontrol agent, Streptomyces caeruleatus WMF106 exhibits good antagonistic effect on the pathogen of walnut blight. To further understand the characteristics and secondary metabolites of this actinomycete, which is beneficial for the application of antimicrobial agent in the control of the disease, the whole genome sequencing of strain WMF106 was conducted, and the sequencing data were analyzed for gene prediction, functional annotation, and analysis of secondary metabolite biosynthesis gene clusters. The results indicated that WMF106 genome consisted of one chromosomal DNA and two plasmid DNAs. The genome of chromosomal DNA was 10,377,577 bp long with the G+C content of 71.16%, encoding 9 253 protein-coding genes. Genes annotated in NR, eggNOG, Swiss-port, KEEG, GO, CAZy, TCDB, CARD, PHI, and VFDB databases numbered 8981, 7933, 5787, 2979, 6426, 510, 1319, 142, 7 and 1507, respectively. In addition, 36 biosynthetic gene clusters were identified, and several of them associated with antibacterial activity were detected, such as those responsible for the biosynthesis of collinomycin, 1,3,6,8-THN, coelichelin and ε-poly-L-lysine. The genome did not contain typical virulence factors and had high biosafety. The genetic background and biocontrol potential of strain WMF106 were clarified, which provided important genetic resources and theoretical support for the discovery of new antibacterial active substances and the development of biological control agents for walnut blight.

Key words: Streptomyces caeruleatus, walnut blight, whole genome sequencing, gene annotation, secondary metabolism, biocontrol