Table 1 Most successful combination of parameters for P. morum transformation using a PDS-1000/He biolistic device

Material of microprojectiles

gold

Size of microprojectiles

0.6 μm in diameter

Selectable marker plasmid

pPmr3

Coating of microprojectiles

plasmid-DNA/microcarrier/CaCl₂/spermidine/ ethanol -precipitation

Target cells

immobilized on cellulose acetate membrane filter; almost free of liquid

Burst pressure of rupture disk

1350 psi

Rupture disk-macrocarrier distance

7 mm

Macrocarrier-stopping screen distance

8 mm

Stopping screen-target cell distance

6 cm

Chamber evacuation

27 inch Hg

Cultivation after particle bombardment

in liquid medium