gacS基因在荧光假单胞菌FD6防治番茄灰霉病中的功能分析

 荧光假单胞菌（Pseudomonas fluorescens）FD6可产生多种抗菌物质，对多种植物病原真菌生长都有抑制作用。将FD6菌株感应激酶gacS基因部分保守区片段克隆到自杀载体中得到质粒pBS-S，将该质粒电击转化到FD6菌株中，利用同源重组构建了gacS基因插入突变体。经测定该突变体不产生抗生素硝吡咯菌素、2,4–二乙酰基间苯三酚、藤黄绿脓菌素、蛋白酶和氢氰酸，与野生型菌株相比形成生物膜和嗜铁素能力显著降低，并且丧失了对番茄灰霉病防病能力。gacS基因互补试验结果表明，gacS基因表达可恢复产生次生抗菌物质的能力，且对番茄灰霉病的防治效果与野生型菌株接近。由此证明，gacS基因是影响拮抗细菌FD6抗生素产生和对病害抑制能力的重要调控因子。

Functional Analysis of the gacS Gene in a Tomato Grey Mould Suppressive Bacterium Pseudomonas fluorescens FD6

Pseudomonas fluorescens FD6 strain produces several antifungal metabolites and inhibits mycelial growth of many plant pathogenic fungi. The partial sequence of sensor kinase gacS gene was PCR-amplified and used to construct a suicide vector pBS-S，which was introduced into strain FD6 to generate a gacS gene-insertion mutant FD6-MS by homologous recombinant. FD6-MS could not produce pyrrolnitrin，2,4-diacetylphloroglucinol，pyoluteorin，proteinase and HCN，and the siderphore production and biofilm formation were markedly reduced. The mutant FD6-MS failed to protect tomato fruits from grey mould caused by Botrytis cinerea HY2-1. The gacS complementary strain could restore the production of above antifungal compounds and protective effect against tomato grey mold. Our results suggest that the gacS gene in strain FD6 act as an important regulatory element in antibiotic production and disease suppression activity.