The large tribe of Triticeae encompasses several important cereal crops, including bread wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). One of the major outcomes of the domestication process of selected Triticae species has been the increased number of grains per inflorescence in modern cultivars -- due to a boost in the crop's floret fertility.
All Triticeae plants produce an unbranched inflorescence, referred to as a spike. In wheat, the spike is made up of several spikelets, which each generate an indeterminate number of grain-producing florets. At the floral developmental stage called "white anther," each wheat spikelet normally produces up to 12 potentially fertile floret primordia. However, more than 70% of the florets abort during their development. Whilst it is known that the number of grains set per spikelet is determined by the fertility of each floret, the genetic basis for floret fertility was recently still widely unidentified. An international group of researchers, including several scientists from the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK Gatersleben), have now collaborated in an effort to decode the genetic basis of floret fertility in wheat.
Researchers - Trait - Loci - QTL - Grain
The researchers focussed on the quantitative trait loci (QTL) responsible for an enhanced grain number per spikelet, which was previously identified by a genome-wide association analysis of European winter bread wheat. They were able to map the QTL and identified the gene Grain Number Increase 1 (GNI-A1), which had evolved in the Triticeae through gene duplication, on chromosome arm 2AL.
The scientists showed that the resulting GNI-A1 encoded a homeodomain leucine zipper class I (HD-Zip I) transcription factor. The expression of the transcription factor resulted in the inhibition of the growth and development of the wheat rachilla, the axis bearing the florets within the spikelets, therefore negatively affected floret fertility and grain yield.
Course - Domestication
Over the course of domestication,...
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