Dissecting pleiotropic functions of the wheat Green Revolution gene Rht-B1b in plant morphogenesis and yield formation.

Abstract

The utilization of reduced plant height genes Rht-B1b and Rht-D1b encoding homeologous DELLA proteins led to the wheat Green Revolution (GR). However, the specific functions of the GR genes in yield determination and the underlying regulatory mechanisms remained unknown. Here we validated that Rht-B1b as a representative of the GR genes affected plant architecture and yield component traits. The up-regulation of Rht-B1b reduced plant height, leaf size and grain weight, but increased tiller number, tiller angle, spike number per unit area (SN), and grain number per spike (GNS). Dynamic investigations showed that Rht-B1b increased SN by improving tillering initiation not outgrowth and enhanced GNS by promoting floret fertility. Rht-B1b reduced plant height by reducing cell size in the internodes, and reduced grain size or weight by decreasing cell number in the pericarp. Transcriptome analyses uncovered that Rht-B1b regulated many homologs of previously reported key genes for given traits and several putative integrators for different traits. These findings specify the pleiotropic functions of Rht-B1b in improving yield and broaden new insights into the regulatory mechanism underlying plant morphogenesis and yield formation.