欧美杨细菌性溃疡病菌双组分系统lqp0812-lqp0813基因功能研究

  Lonsdalea quercina subsp. populi引起的欧美杨溃疡病是严重威胁欧美杨人工林生产的细菌性病害。双组分系统是细菌最重要的信号转导通路之一,在细菌的生长繁殖、环境适应、胁迫耐受性以及致病过程中发挥重要作用。为探索L. quercina 中双组分系统编码基因的功能,本研究利用同源重组对双组分系统编码基因lqp0812和lqp0813进行缺失突变,并研究其生物学功能。表型分析显示,与野生型菌株N-5-1相比,Δlqp0812和Δlqp0813突变体在生长速率、金属离子胁迫、盐胁迫、渗透胁迫及致病性方面没有显著差异;但Δlqp0812突变体在游动性上与野生型N-5-1相比显著减弱;Δlqp0812和Δlqp0813突变体生物被膜的形成能力,对过氧化氢、抗生素的耐受性都显著增强。qRT-PCR结果显示,在Δlqp0812和Δlqp0813突变体中,外排泵基因acrA、mdtB、aaeB的表达量与野生型相比显著升高。研究结果表明,lqp0812参与病原菌的游动性,lqp0812与lqp0813共同负调控菌株生物膜的形成和对氧化胁迫、抗生素胁迫的耐受性。

Functional analysis of lqp0812-lqp0813 genes of the two-component system from Lonsdalea quercina subsp. populi

Poplar canker disease caused by Lonsdalea quercina subsp. populi is a bacterial disease that seriously threatens the production of Populus × euramericana plants. The two-component system is one of the most important signal transduction pathways and plays a crucial role in the growth, reproduction, adaption, stress tolerance and pathogenicity of bacteria. To explore the function of two-component system encoding genes in L. quercina, this study used homologous recombination to carry out deletion mutations on the two-component system encoding genes lqp0812-lqp0813 in strain N-5-1, and studied their biological functions. Compared with the wild-type strain, the growth rate, tolerances to heavy metal stress, salt stress, osmotic stress and pathogenicity were not changed in Δlqp0812 and Δlqp0813 mutants. However, the swimming motility was significantly impaired in Δlqp0812 mutant than that of the wild-type. In addition, the biofilm formation, hydrogen peroxide and antibiotic resistance were significantly increased in Δlqp0812 and Δlqp0813 mutants compared with the wild-type. qRT-PCR analysis showed that the expression levels of the efflux pump genes acrA, mdtB and aaeB were greatly increased in the lqp0812 and lqp0813 deletion mutants. These results indicated that lqp0812 is involved in the swimming motility of L. quercina subsp. populi, and lqp0812 and lqp0813 negatively regulated biofilm formation and tolerance to H₂O₂ and antibiotic stress together.