Variation in Streptomycin Resistance Mechanisms in Clavibacter michiganensis

Abstract

Clavibacter michiganensis is the causal agent of bacterial canker of tomato, which causes significant economic losses because of the lack of resistant tomato varieties. Chemical control with streptomycin or cupric bactericides is the last defensive line in canker disease management. Streptomycin is an aminoglycoside antibiotic that inhibits protein synthesis and targets the 30S ribosomal protein RpsL. Streptomycin has been used to control multiple plant bacterial diseases. However, identification and characterization of streptomycin resistance in C. michiganensis have remained unexplored. In this study, a naturally occurring C. michiganensis strain TX-0702 exhibiting spontaneous streptomycin resistance was identified, with a minimum inhibitory concentration of 128 μg/ml. Additionally, an induced streptomycin-resistant strain BT-0505-R was generated by experimental evolution of the sensitive C. michiganensis strain BT-0505. Genome sequencing and functional analyses were used to identify the genes conferring resistance. A point mutation at the 128th nucleotide in the rpsL gene of strain BT-0505-R is responsible for conferring streptomycin resistance. However, in TX-0702, resistance is not attributed to mutation of rpsL, streptomycin inactivation enzymes, or multidrug efflux pumps. The mechanism of resistance in TX-0702 is independent of previously reported bacterial loci. Taken together, these data highlight diverse mechanisms used by a Gram-positive plant pathogenic bacterium to confer antibiotic resistance.

Deletion of pbpC Enhances Bacterial Pathogenicity on Tomato by Affecting Biofilm Formation, Exopolysaccharides Production, and Exoenzyme Activities in Clavibacter michiganensis

“…Strain GS12102 harbors two plasmids, pCM1 and pCM2; the other strain, BT0505 only harbors pCM1. The knock-out mutants of pbpC and the complementation strains were prepared as previously described [ 17 , 67 ]. The C. michiganensis strains were grown on Luria–Bertani (LB) agar or in LB broth medium (10 g of tryptone, 5 g of yeast extract, 5 g of NaCl, and 16 g of agar for solid medium per liter) at 28 °C for 72 h, whereas the Escherichia coli strains were cultured at 37 °C with shaking as required (at 160 or 200 rpm).…”

A Genetic Toxicology Study of the Rapid Detection of Nitrosamine Compounds by the rpsL Gene Mutation Assay

“…Under normal circumstances, the combination of streptomycin and S12 protein makes the protein biosynthesis unable to proceed, and the cell stops growing; the mutation of the rpsL gene makes the streptomycin loose effective binding with S12 protein, so that the strain with this gene mutation has resistance to streptomycin. It can grow on plates containing streptomycin, so mutant strains were selected [12,13]. The host strain MF101 used in this experiment has streptomycin resistance, and the plasmid pMOL21 contains ampicillin resistance and the rpsL gene sequence [14].…”

Physiological responses and antibiotic-degradation capacity of duckweed (Lemna aequinoctialis) exposed to streptomycin

“…Streptomycin is an aminoglycoside antibiotic with a molecular formula C 21 H 39 N 7 O 12 . Due to its simple availability and cost effectiveness, streptomycin is usually used alone or in combination with other antibiotics to treat bacterial diseases ( Lyu et al., 2019 ). Streptomycin is also widely used in agricultural production to prevent and control plant diseases caused by various pathogenic microorganisms ( Walsh et al., 2014 ).…”