Location: Cereal Crops Research
Title: Molecular and comparative mapping of genes governing spike compactness inherited from wild emmer wheat Authors
Submitted to: Molecular Genetics and Genomics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2014
Publication Date: March 23, 2014
Citation: Faris, J.D., Zhang, Z., Garvin, D.F., Xu, S.S. 2014. Molecular and comparative mapping of genes governing spike compactness inherited from wild emmer wheat. Molecular Genetics and Genomics. DOI 10.1007/s00438-014-0836-2 Interpretive Summary: The development and morphology of the wheat spike, or head, is important because the spike is where reproduction occurs and it holds the grains until harvest. Therefore, genes that influence spike morphology are of interest from both theoretical and practical stand points. Wild emmer wheat is a wild relative of today's durum and bread wheat, and it is often used as a source of useful genes for improvement of modern varieties. In this research, we evaluated genes in a wild emmer wheat line that influenced spike length and the number of spikelets per spike, the latter of which is an important yield component. We found that the two traits are controlled by different genes on the same chromosome, and the forms of the genes contributed by the wild emmer wheat accession conferred fewer spikelets per spike and a shorter spike compared to modern day durum wheat. Further analysis suggested that the gene governing spike length might be a form of the same gene found in barley that also influences spike length as well as flowering time and cleistogamy, or openness of the florets. Other research has suggested that shorter more compact spikes may help increase tolerance to drought. Therefore, the gene conferring a shorter, more compact spike derived from wild emmer might be useful for the improvement of drought resistance in modern durum varieties.
Technical Abstract: The development and morphology of the wheat spike is important because the spike is where reproduction occurs and it holds the grains until harvest. Therefore, genes that influence spike morphology are of interest from both theoretical and practical stand points. When substituted for the native chromosome 2A in the tetraploid Langdon (LDN) durum wheat background, the Triticum turgidum ssp. dicoccoides chromosome 2A from accession IsraelA confers a short, compact spike with fewer spikelets per spike compared to LDN. Molecular mapping and quantitative trait loci (QTL) analysis of these traits in a homozygous recombinant (HR) population derived from LDN × the chromosome 2A substitution line (LDNIsA-2A) indicated that the number of spikelets per spike and spike length were controlled by linked, but different, loci on the long arm of 2A. A QTL explaining most of the variation for spike compactness coincided with the QTL for spike length. Comparative mapping indicated that the QTL for number of spikelets per spike overlapped with a previously mapped QTL for Fusarium head blight susceptibility. The genes governing spike length and compactness were not orthologous to either sog or C, genes known to confer compact spikes in diploid and hexaploid wheat, respectively. However, it is possible that the gene governing spike length and compactness derived from wild emmer could be a homolog of the barley Cly1 gene, which is an AP2-like gene affecting cleistogamy, flowering time, and rachis internode length.