ARS | Publication request: Gene Flow from Cultivated Sorghum to Weedy Relatives

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: April 30, 2010
Publication Date: June 21, 2010
Citation: Pedersen, J.F., Schmidt, J.J., Lindquist, J.L., Bernards, M.L. 2010. Gene Flow from Cultivated Sorghum to Weedy Relatives. Meeting Proceedings presented at 2010 Australian Summer Grains Conference, Gold Coast, QLD June 21-24.

Interpretive Summary: Sorghum is usually self pollinating, but may vary in extent of outcrossing due to openness of the head and proximity to other compatible sorghum plants. Previous researchers have shown that sorghum crosses at considerable distance from a pollen source using male sterile lines as seed parents. Our research describes the extent of outcrossing of self-fertile shattercane growing in a soybean field at varying distances from cultivated sorghum. Outcrossing was 3.6% for shattercane planted within the cultivated sorghum and declined to 0.09% at 200 m. Progeny from 101 of 105 panicles evaluated at greater than 10m contained outcrossed seed. Results from a separate study on the fitness of shattercane x sorghum hybrids indicate that the relative fitness of shattercane x sorghum hybrids may be equal to or greater than the wild shattercane parent. Additional studies are planned to investigate fitness of succeeding generations of such hybrid populations, and to model gene flow in shattercane populations. Results will be important in developing management strategies for sorghum with transgenic or herbicide resistance traits.

Technical Abstract: Sorghum (Sorghum bicolor) is predominately sexually self-compatible, but may vary in extent of outcrossing due to panicle morphology and proximity to other compatible individuals. Using male-sterile lines and field designs not typical of production agriculture, previous researchers have documented the ability for sorghum to cross at considerable distance from a pollen source. Our research documents in situ outcrossing of self-fertile shattercane (S. bicolor subsp. drummondii) growing in a soybean (Glycine max (L.) Merr.) field at varying distances from a cultivated sorghum pollen source and flowering in synchrony with that source. Outcrossing was 3.6% for shattercane planted within the cultivated sorghum and generally declined to 0.09% at 200 m. Progeny from 101 of the 105 panicles evaluated at =10m contained outcrossed seed. Results from a separate study on the fitness of shattercane x cultivated sorghum hybrids indicate that the relative fitness of shattercane x cultivated sorghum F1 hybrids may be equal to or greater than the wild shattercane parent. Studies are planned to investigate fitness of F2 populations, and to model gene flow in shattercane populations. These results will be important in developing management strategies for sorghum with transgenic or herbicide resistance traits.