Pollen-mediated transformation of Sorghum bicolor plants.

Pollen from sorghum (Sorghum bicolor L. Moench) were transformed by a novel genetic transformation approach using mild ultrasonication. The plasmid pBI121 contained the NPT II gene encoding NPT II (neomycin phosphotransferase II) and a GUS (beta-glucuronidase) reporter gene. Plasmid DNA and pollen from sorghum A(2)V4B were submerged in a 0.3 mol/l sucrose solution and then subjected to ultrasonication. The treated pollen was then used for pollination of stigmas from the male sterile line A(2)V4A. Detection of transient and stable GUS activity confirmed that the GUS gene was expressed in transgenic plants. PCR amplification and Southern-blot analysis of transgenic plants confirmed that the NPT II gene had been integrated into the sorghum genome. These results indicate that direct gene transfer to pollen can be mediated by mild ultrasonication.