The toxicity of antibiotics and herbicides on in vitro adventitious shoot formation on Pinus pinea L. cotyledons

The toxicity of three antibiotics commonly used to eliminate Agrobacterium tumefaciens from plant tissue during transfomation were tested to determine their effect on Pinus pinea L. morphogenesis. Cefotaxime and vancomycin at a dose of 250 mu g ml(-1), as well as ticarcillin at 300 mu g ml(-1), were essentially? nontoxic to the culture and significantly enhanced regenerati on and shoot development. Kanamycin, a,widely used selection agent for plan t transformation, strongly inhibited regeneration even at very low dose;. O n the contrary, phosphinothricin and its ammonium salt glufosinate in the c ommercial formulation Finale(R) proved to be the best selection agents beca use the! were less toxic to stone pine cotyledons. Thus, the! could be appl ied immediately after transformation to avoid escapes. Other schemes for se lection and recovery of transgenic stone pine trees are discussed.