LAUSR

Spike architecture influences grain yield in wheat. We report the map-based cloning of a gene determining the number of spikelet nodes per spike in common wheat. The cloned gene is named TaCOL-B5 and encodes a CONSTANS-like protein that is orthologous to COL5 in plant species. Constitutive overexpression of the dominant TaCol-B5 allele but without the region encoding B-boxes in a common wheat cultivar increases the number of spikelet nodes per spike and produces more tillers and spikes, thereby enhancing grain yield in transgenic plants under field conditions. Allelic variation in TaCOL-B5 results in amino acid substitutions leading to differential protein phosphorylation by the protein kinase TaK4. The TaCol-B5 allele is present in emmer wheat but is rare in a global collection of modern wheat cultivars. Description Increasing wheat grain yield In wheat, the numbers of tillers, spikes, and spikelets determine how much grain is produced. Beginning with a cross between two common wheat cultivars, Zhang et al. cloned a gene that affects wheat plant architecture and, consequently, grain yield (see the Perspective by van Esse). Exon capture analyses identified the same gene in wild emmer wheat. The gene nonetheless remains rare among contemporary US wheat cultivars. In field trials in Jiangsu, China, overexpression of the dominant allele in transgenic wheat increased grain production by about 12%. —PJH A gene identified in two common wheat cultivars and also found in wild emmer wheat can enhance yield in modern wheat cultivars.