Inhibition of extracellular DNase activity of barley microspores in the presence of polyethylene glycol and silicon carbide fibers

Nucleolytic activity was detected extracellularly in barley microspore (MS) cultures directly for up to 6 days after isolation. Treatment of MS with p olyethylene glycol (PEG) enhanced nucleolytic activity, whereas the additio n of silicon carbide fibers (SCF) resulted in some protection of DNA. Extra cellular nucleolytic activity was reduced when MS were treated with 12% PEG after addition of a mixture of 8 mmol/L dNTP, 8 mmol/L EDTA, 40 mmol/L spe rmidine and 1.7 mg/mL proteinase K. In the presence of SCF a mixture withou t nucleotides was also effective. Gene transfer approaches with PEG and SCF were carried out under conditions of nuclease inhibition, but transient GU S activity was obtained very rarely.