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GrainGenes Reference Report: GCE-48-507

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Zymogram patterns of alpha-amylase isozymes in Ethiopian tetraploid wheat landraces: insight into their evolutionary history and evidence for gene flow
Genetic Resources and Crop Evolution
Belay G
Furuta Y
Summary: The variation for alpha-amylase isozymes was analyzed in 71 tetraploid wheat (AABB genome) landraces from Ethiopia, including accessions of Triticum dicoccon Shrank, T. turgidum L., T. durum Desf., T. pyramidale Percival and T. aethiopicum Jakubz., by thin-layer polyacrylamide gel isoelectric focusing. Four zymogram phenotypes were obtained from all the materials studied. Except in T. dicoccon, however, the standard pattern of the durum wheat variety, LD222, was predominant. T. dicoccon showed two zymogram types that differed for the absence or consistently weak activity of band 18 (alpha-Amy-B1) of the malt type. Band 1 (alpha-Amy-B3) of the malt type was fixed in T. dicoccon and present in only 10% of the free-threshing (FT) types. Generally, the results indicated that the variation for alpha-amylase isozymes in cultivated tetraploid wheats, including landraces from secondary centers, is low possibly due to the founder effect or as a result of selection. The data were useful for inferences about the evolutionary history of Ethiopian wheat landraces. It is speculated that T. dicoccon was the first wheat to arrive in the Ethiopian highlands ca. 5000 years ago. However, it is not known whether the present day FT Ethiopian tetraploid wheat landraces are direct descendants of T. dicoccon, or whether they were introduced independently. The clear differences in alpha-amylase zymogram patterns favor the latter hypothesis. However, the presence of band 1 in some of the FT types indicated the occurrence of gene flow between the FT types and T. dicoccon, which may also explain the quantitative nature of spike threshability in these landraces. Possible implications for durum wheat breeding are discussed
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