|Marx, D - UNI OF NE|
Submitted to: Crop Science
Publication Type: Abstract Only
Publication Acceptance Date: July 29, 2002
Publication Date: N/A
Technical Abstract: A critical impediment to field testing and deployment of transgenic sorghum (Sorghum bicolor (L.) Moench) is the risk of gene flow to weedy relatives through pollen. A technique using sorghum with A3 cytoplasmic male sterility to control transgene flow through pollen while using non-transgenic pollinators is described. An experiment was designed to evaluate risk of viable pollen flow using the technique under field conditions. Percent seed set under pollinating bags (an indicator of fertile pollen) was evaluated on selfed F2 progeny grown from open pollinated seed of twelve F1 hybrids produced in A1 and A3 cytoplasm. Seed was produced in hybrid yield trials in 1997 and 1998 at the University of Nebraska Field Laboratory in Ithaca, NE. Cytoplasm was nested within hybrid and four replications were used per year. Cytoplasm effects were highly significant, with seed set on A1 F2 individuals averaging 71%, and seed set on A3 F2 individuals averaging 0.0%. Percent seed set was not significantly different (P=0.05) from zero for selfed A3 F2 progeny from all twelve hybrids. Upper confidence limits (P=0.05) for percent seed set were 1.2% or less for the progeny from all hybrids. These results indicate that gene flow through pollen can be severely restricted in sorghum.