Response of in vitro strawberry to antibiotics

By identifying antibiotics that had the least phytotoxic effects on explants during genetic transformation, we evaluated the effect of various antibiotics on callus induction and morphogenesis from leaf explants and in vitro growth of Fragaria x ananassa Duch. cv. Toyonaka. Results showed that kanamycin (Kan) significantly inhibited callus induction, bud differentiation and root morphogenesis while carbenicillin (Carb), cefotaxime (Cef) and an equal concentration of Cef and Carb up to 500 mg L-1 had no significant effects on callus induction and shoot growth. Kan, even at 2.5 mg L-1, significantly inhibited callus induction, shoot regeneration and root formation, while no shoots regenerated at concentrations above 15 mg L-1. Rooting was completely inhibited in the presence of 50 mg L-1 Kan. Cef had negative effects on shoot regeneration from leaf explants and in vitro growth of strawberry. Compared to Cef, Carb at a parts per thousand currency sign300 mg L-1 significantly promoted shoot and root organogenesis. However, an equal concentration of Carb plus Cef could alleviate the negative effect of Cef on strawberry. Results from relative electrolyte leakage, root and antioxidant activities, O (2) (center dot-) production rate, H2O2, proline and MDA contents showed that Kan, Cef and Carb caused electrolyte leakage and triggered active enzymatic processes and metabolism. This offers a possible mechanism for the inhibition or stimulation of strawberry growth caused by these antibiotics.