Search

Plant and inflorescence architecture determine the yield potential of crops. Breeders have harnessed natural diversity for inflorescence architecture to improve yields, and induced genetic variation could provide further gains. Wheat is a vital source of protein and calories; however, little is known about the genes that regulate the development of its inflorescence. Here, we report the identification of semidominant alleles for a class III homeodomain-leucine zipper transcription factor, HOMEOBOX DOMAIN-2 ( HB-2 ), on wheat A and D subgenomes, which generate more flower-bearing spikelets and enhance grain protein content. These alleles increase HB-2 expression by disrupting a microRNA 165/166 complementary site with conserved roles in plants; higher HB-2 expression is associated with modified leaf and vascular development and increased amino acid supply to the inflorescence during grain development. These findings enhance our understanding of genes that control wheat inflorescence development and introduce an approach to improve the nutritional quality of grain.

Bulk phenotype during fruit development and parental line phenotype at the mature fruit stage. A. Average weight of fruits sampled for the BSAseq. Each point represents the mean of three repeats from each of the 25 F3 families that comprise each bulk. The green and orange dots and lines represent the green and orange flesh bulks respectively. The orange dots and line represent the orange flesh bulk. X axis is DAA. No significant fruit weight differences were detected. B. Mature fruit weight of the parental lines. Each column represents the average of 6 fruits. Error bars are standard error of the mean. C. Histograms show proportion of different weight groups (Kg) in the entire population (gray columns) and in the sampled orange and green fruit (orange and green columns respectively). The orange and green subpopulations display normal distribution around the mean according to Goodness of Fit test. (Jump-8 software). C. Chroma-meter (Minolta Sensing Inc, Minolta Chroma Meter Model CR-400, Osaka, Japan) measurements of the developing fruits described in A. Each cut-open fruit was measured at three points of the mesocarp center. The Y axes colored bars illustrate the color range of a*, b* and l* values (see material and methods). D. Chroma-meter measurements of mature fruits of the parental inbred lines, F1 and the bulks. Dulce, Tam-Dew and F1 columns represent the average of six fruits. The bulks mature fruit are the same measurements as in C. E. Total soluble solids (TSS) values in the fruit flesh measured by optical refractometer at three developmental stages. The TSS values of ‘green’ and ‘orange’ bulks at the mature stage are statistically different (P