“…Mapping studies for the several components of grain yield potential have identified QTL on all 21 chromosomes of wheat genome by classical linkage mapping using biparental populations and by GWAS using wheat collections (see reviews [ 32 – 34 ]). Major QTL associated to thousand grain weight were detected on chromosomes 1B, 2A, 2D, 3A, 3B, 4B, 4D, 5A, 5B, 6A, 7B and 7D [ 16 , 35 – 52 ], and QTL for grain number per spike on chromosomes 2B, 3B, 4A, 4B, 4D, 5A, 5D, 7A and 7B [ 33 , 36 – 38 , 43 , 48 , 53 – 59 ]. Current development of advanced biotechnologies have recently allowed the identification of some key genes for significant increases in grain weight or grain number per spike in wheat by comparative genomics with rice [ 60 ].…”