Snow, Allison , Sweeney, P. M. , Grenier, C. , Kapran, I. , Tesso, T. , Bothma, G. , Ejeta, G. , Pedersen, J. F. .
Lifetime fecundity of F1 crop-wild sorghum hybrids: implications for gene flow from transgenic sorghum in Africa.
Researchers are developing transgenic crops with enhanced nutrition and higher yields for Africa, but few studies have assessed possible environmental risks of growing these crops. Plans to release transgenic sorghum (Sorghum bicolor) should consider consequences of gene flow to wild relatives, which represent valuable germplasm and sometimes occur as weeds. Our previous studies in Ethiopia and Niger showed that wild and cultivated sorghum often co-occur and flower simultaneously. Here, we tested for spontaneous hybridization between accessions of wild S. bicolor and local cultivars from eastern Africa at times when their flowering periods overlapped. Plants were grown in field plots in Ohio, with a ratio of more than 20 crop plants per wild individual. Microsatellite DNA markers showed that some seeds on wild plants were fertilized by crop pollen, as expected. We also studied the lifetime fecundity of F1 hybrids between a male-sterile cultivar and three wild accessions. Wild and hybrid progeny were grown in common garden experiments in Niger, Ohio, and Indiana. The relative fecundity of hybrids was fairly consistent across locations and differed somewhat among accessions. For two accessions, crop-wild hybrids produced considerably more seeds per plant than the wild parent. For a third accession, hybrids produced fewer seeds per plant in the USA and similar numbers of seeds per plant in Niger. In all crosses, F1 crop-wild hybrids were vigorous and fertile, indicating the ease with which this generation can contribute pollen and seeds to subsequent generations. This study shows that selectively neutral or advantageous crop alleles are expected to persist in wild sorghum populations following hybridization. Before transgenic sorghum varieties are grown in the vicinity of its wild relatives in Africa, consequences of crop-to-wild gene flow should be examined on a case-by-case basis, taking into account the transgenic traits involved and their ecological effects on other organisms.
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1 - Ohio State University, Department of Evolution, Ecology and Organismal Biology, 300 Aronoff Laboratory, 318 W. 12th Ave., Columbus, Ohio, 43210-1293, USA
2 - Purdue University, Department of Agronomy, West Lafayette, IN, 47907, USA
3 - Institut National de la Recherche Agronomique du Niger, Niamey, BP429, Niger
4 - Ethiopian Institute of Agricultural Research, Melkassa Research Center, PO Box 436, Nazareth, Ethiopia
5 - ARC-Roodeplaat, Pretoria, South Africa
6 - US Dept of Agriculture ARS, 344 Keim Hall, University of Nebraska, Lincoln, NE, 68583, USA
genetically engineered plants
Crop-to-Wild Gene Flow
Presentation Type: Oral Paper:Papers for Topics
Location: Williford A/Hilton
Date: Tuesday, July 10th, 2007
Time: 11:45 AM