 Wheat (source code)

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= Wheat

<Wheat> refers to cereal <grasses> of the <taxonomic genus> <Triticum>, cultivated for their grain. Bread wheat, <Triticum aestivum>, exhibits <allopolyploidy>: its somatic cells contain six chromosome sets, conventionally written AABBDD, totaling $2n=42$. The letters distinguish three related ancestral genomes, each represented twice.<Dual effect of the wheat Ph1 locus on chromosome synapsis and crossover by Azahara C. Martín and others>[Introduction, genome constitution]{ref}

This ancestry creates a problem during <meiosis>. A chromosome must normally pair and exchange <DNA> with its true <homologous chromosome>, rather than with a related chromosome from a different ancestral genome. The <Ph1 locus> helps stabilize that choice. In experiments comparing wheat with and without this locus, researchers used chromosome imaging and markers of <chromosome synapsis> and <chromosomal crossover>. Loss of Ph1 delayed synapsis relative to the stage at which chromosome ends cluster, allowing more opportunity for pairing between related chromosomes. The experiments also changed growth conditions and measured resulting crossovers.<Dual effect of the wheat Ph1 locus on chromosome synapsis and crossover by Azahara C. Martín and others>[Abstract and Results]{ref}

<Polyploidy> therefore involves more than carrying extra DNA: successful reproduction requires mechanisms that organize related chromosomes into reliably inherited sets.

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