Laboratorio de Bioproducción, Plataforma de Bioinsumos, INIA Las Brujas, Canelones, Uruguay.
Laboratorio de Protección Vegetal, INIA Las Brujas, Canelones, Uruguay; Laboratorio de Ecología Química, Facultad de Química, Universidad de la República, Montevideo, Uruguay.
Syst Appl Microbiol. 2021 Apr;44(2):126177. doi: 10.1016/j.syapm.2020.126177. Epub 2021 Jan 2.
Serratia marcescens can be a plant growth promoting bacteria (PGPB) and an opportunistic human and plant pathogen. We have identified and characterized strains of related species of Serratia and evaluated their biological control of damping-off of tomato seeds caused by Pythium cryptoirregulare. Serratia ureilytica, S. bockelmannii and S. nevei were identified by phylogenetic analysis of partial gyrB gene sequence and average nucleotide identity (ANI). Tomato seeds inoculated with S. ureilytica ILBB 145 showed higher germination percentage and reduced damping-off in greenhouse experiment resembling a commercial operation, and volatiles produced by this strain caused the nearly complete inhibition in vitro of P. cryptoirregulare. Analysis of volatile organic compounds (VOCs) showed that ILBB 145 produced dimethyl disulfide (DMDS), which can partially account for this inhibition. Serratia bockelmannii ILBB 162 performance against damping-off was intermediate and the inhibition of P. cryptoirregulare in vitro was lower and explained by volatile and diffusible metabolites. Both strains augmented DMDS production in the presence of P. cryptoirregulare, suggesting this compound may play a role in the context of interspecific competition. Serratia nevei ILBB 219 showed the lowest inhibition of P. cryptoirregulare in vitro, no DMDS production, and no biocontrol in planta. Draft genomes of the three strains were annotated and individual genes and biosynthesis gene clusters were identified in relation with the observed phenotypes. We report S. ureilytica - a low risk species- with activity as a biological control agent and DMDS produced by this bacterial species putatively involved in seed and seedling protection against P. cryptoirregulare.
粘质沙雷氏菌可以是一种植物促生细菌（PGPB）和机会性人类和植物病原体。我们已经鉴定和表征了相关种属的沙雷氏菌菌株，并评估了它们对由腐霉菌引起的番茄种子猝倒病的生物防治效果。通过部分gyrB 基因序列和平均核苷酸同一性（ANI）的系统发育分析鉴定出了 S. ureilytica、S. bockelmannii 和 S. nevei。温室实验中，用 S. ureilytica ILBB 145 接种的番茄种子表现出更高的发芽率和减少猝倒病，类似于商业操作，并且该菌株产生的挥发物在体外几乎完全抑制腐霉菌。挥发性有机化合物（VOCs）分析表明，ILBB 145 产生二甲基二硫（DMDS），这可以部分解释这种抑制作用。S. bockelmannii ILBB 162 对猝倒病的防治效果居中，体外对腐霉菌的抑制作用较低，这可以用挥发性和可扩散代谢物来解释。这两种菌株在存在腐霉菌的情况下都增加了 DMDS 的产生，表明这种化合物可能在种间竞争的背景下发挥作用。S. nevei ILBB 219 体外对腐霉菌的抑制作用最低，不产生 DMDS，在植物体内也没有生物防治作用。对这三种菌株的基因组草案进行了注释，并鉴定了与观察到的表型相关的单个基因和生物合成基因簇。我们报告了 S. ureilytica-一种低风险物种-具有生物防治剂的活性，并且该细菌物种产生的 DMDS 可能参与了对腐霉菌的种子和幼苗的保护。
