The effect of endophytic bacteria on in vitro shoot growth of Prunus yedoensis and its identification and elimination

Abstract

Tissue cultures of Prunus yedoensis, a famous ornamental tree species, are important to mass-propagate true-to-type plants. Within in vitro cultures, bacterial contamination of explants hinders the propagation of sustainable cultures. Negative effects of endophytic bacteria vary from leaf yellowing to shoot-tip necrosis, ultimately resulting in shoot death. Explants with an overgrowth of endophytic bacteria on basal parts showed inferior growth than explants with no bacterial growth. Shoot growth and contamination became severe as the shoots were subcultured. Two endophytic bacteria, Pantoea spp. and Curtobacterium spp., were identified from the in vitro shoots using 16S rRNA gene sequences. Bacterial susceptibility to antibiotics was screened using different antibiotics. Two antibiotics, cefotaxime and tetracycline, effectively controlled bacteria growth. Although both antibiotics killed the bacteria, tetracycline adversely affected plant growth by reducing shoot growth. A broad range of cefotaxime concentrations had no toxic effects to the in vitro plants. However, concentrations between 50 and 150 mg/L showed no difference in eliminating bacteria. Shoot growth, induction, and elongation were greater in a medium supplemented with cefotaxime compared with a control (without antibiotics) and a medium amended with tetracycline.