Table_4_Comparative genomics provides insights into the potential biocontrol mechanism of two Lysobacter enzymogenes strains with distinct antagonistic activities.DOCX

Lysobacter enzymogenes has been applied as an abundant beneficial microorganism to control plant disease; however, most L. enzymogenes strains have been mainly reported to control fungal diseases, not bacterial diseases. In this study, two L. enzymogenes strains were characterized, of which CX03 displayed a broad spectrum of antagonistic activities toward multiple bacteria, while CX06 exhibited a broad spectrum of antagonistic activities toward diverse fungi and oomycete, and the whole genomes of the two strains were sequenced and compared. The genome annotation showed that the CX03 genome comprised a 5,947,018 bp circular chromosome, while strain CX06 comprised a circular 6,206,196 bp chromosome. Phylogenetic analysis revealed that CX03 had a closer genetic relationship with L. enzymogenes ATCC29487T and M497-1, while CX06 was highly similar to L. enzymogenes C3. Functional gene annotation analyses of the two L. enzymogenes strains showed that many genes or gene clusters associated with the biosynthesis of different secondary metabolites were found in strains CX03 and CX06, which may be responsible for the different antagonistic activities against diverse plant pathogens. Moreover, comparative genomic analysis revealed the difference in bacterial secretory systems between L. enzymogenes strains CX03 and CX06. In addition, numerous conserved genes related to siderophore biosynthesis, quorum sensing, two-component systems, flagellar biosynthesis and chemotaxis were also identified in the genomes of strains CX03 and CX06. Most reported L. enzymogenes strains were proven mainly to suppress fungi, while CX03 exhibited direct inhibitory activities toward plant bacterial pathogens and showed an obvious role in managing bacterial disease. This study provides a novel understanding of the biocontrol mechanisms of L. enzymogenes, and reveals great potential for its application in plant disease control.

产酶溶杆菌（Lysobacter enzymogenes）作为一类资源丰富的有益微生物，已被广泛应用于植物病害防控；然而，绝大多数已报道的产酶溶杆菌菌株主要被证实可防控真菌病害，而非细菌病害。本研究对两株产酶溶杆菌菌株进行了系统表征：其中CX03对多种细菌展现出广谱拮抗活性，而CX06则对多种真菌及卵菌具有广谱拮抗活性，同时完成了两株菌株的全基因组测序与比较分析。基因组注释结果显示，CX03的基因组包含一条长度为5947018 bp的环状染色体，而CX06菌株的基因组则包含一条长度为6206196 bp的环状染色体。系统发育分析表明，CX03与产酶溶杆菌ATCC29487^T及M497-1的遗传亲缘关系更为密切，而CX06则与产酶溶杆菌C3高度相似。对两株产酶溶杆菌菌株的功能基因注释分析显示，CX03与CX06的基因组中均存在大量与不同次生代谢产物生物合成相关的基因及基因簇，这可能是二者对多种植物病原物展现出差异化拮抗活性的分子基础。此外，比较基因组分析揭示了CX03与CX06在细菌分泌系统层面的差异。同时，两株菌株的基因组中还鉴定出大量与铁载体生物合成、群体感应、双组分系统、鞭毛生物合成及趋化性相关的保守基因。已有研究报道的产酶溶杆菌菌株大多仅被证实可抑制真菌病害，而CX03则对植物细菌性病原物具有直接抑制活性，在细菌性病害的防控中展现出显著作用。本研究为产酶溶杆菌的生防机制提供了全新的认知视角，并揭示了其在植物病害防控领域的巨大应用潜力。