The physiology and genetics behind fruiting efficiency, a promising spike trait to improve wheat yield potential

Abstract

The fruiting efficiency (FE, grains per g of spike dry weight at anthesis) was proposed as a promising spike trait to improve wheat yield potential, based on its functional relationship with grain number determination (the most important component associated with yield potential) and the evidence of trait variability in elite germplasm. During the last years, we have witnessed great advances in the understanding of the physiological and genetic bases of this trait. The present review summarises the recent heritability estimations and the genetic gains obtained when the fruiting efficiency was measured at maturity (FEm, grains per g of chaff) and used as selection criterion. In addition, by revising a detailed physiological approach based on the fertile floret efficiency (FFE, fertile florets per g of spike dry weight at anthesis) and grain set (grains per fertile floret), together with other spike fertility related traits, spike ideotypes for contrasting fruiting efficiencies are proposed. The novel genes and QTL available for using marker-assisted selection for fruiting efficiency and other spike fertility traits are also reviewed. The possible trade-off between FE and grain weight (GW) and the genes reported to alter this relation are revised. Finally, the benefits and future steps towards the use of fruiting efficiency as a selection criterion in breeding programs is discussed.