High-frequency stable transformation of cotton (Gossypium hirsutum L.) by particle bombardment of embryogenic cell suspension cultures

Stable transformation of cotton (Gossypium hirsutum L.) at a high frequency has been obtained by particle bombardment of embryogenic cell suspension c ultures. Transient and stable expression of the beta-glucuronidase (GUS) ge ne was monitored in cell suspension cultures. Transient expression, measure d 48 h after bombardment, was abundant, and stable expression was observed in over 4% of the transiently expressing cells. The high efficiency of stab le expression is due to the multiple bombardment of rapidly dividing cell s uspension cultures and the selection for transformed cells by gradually inc reasing the concentrations of the antibiotic Geneticin (G418). Southern ana lysis indicated a minimum transgene copy number of one to four in randomly selected plants. Fertile plants were obtained from transformed cell culture s less than 3 months old. However, transgenic and control plants from cell cultures older than 6 months produced plants with abnormal morphology and a high degree of sterility.