HvDep1 Is a Positive Regulator of Culm Elongation and Grain Size in Barley and Impacts Yield in an Environment-Dependent Manner

Abstract

Heterotrimeric G proteins are intracellular membrane-attached signal transducers involved in various cellular processes in both plants and animals. They consist of three subunits denoted as α, β and γ. The γ-subunits of the so-called AGG3 type, which comprise a transmembrane domain, are exclusively found in plants. In model species, these proteins have been shown to participate in the control of plant height, branching and seed size and could therefore impact the harvestable yield of various crop plants. Whether AGG3-type γ-subunits influence yield in temperate cereals like barley and wheat remains unknown. Using a transgenic complementation approach, we show here that the Scottish malting barley cultivar (cv.) Golden Promise carries a loss-of-function mutation in HvDep1, an AGG3-type subunit encoding gene that positively regulates culm elongation and seed size in barley. Somewhat intriguingly, agronomic field data collected over a 12-year period reveals that the HvDep1 loss-of-function mutation in cv. Golden Promise has the potential to confer either a significant increase or decrease in harvestable yield depending on the environment. Our results confirm the role of AGG3-type subunit-encoding genes in shaping plant architecture, but interestingly also indicate that the impact HvDep1 has on yield in barley is both genotypically and environmentally sensitive. This may explain why widespread exploitation of variation in AGG3-type subunit-encoding genes has not occurred in temperate cereals while in rice the DEP1 locus is widely exploited to improve harvestable yield.

Genetics of barley tiller and leaf development

“…The barley ari.e‐GP semi‐dwarf locus was widely used in breeding because of desirable effects, including early flowering, salt tolerance, sturdy culms, and shorter awns. This locus was recently shown to correspond to the barley ortholog of the rice Dense and erect panicle1 ( Ari‐e / HvDEP1 ) gene encoding a γ subunit of heterotrimeric G proteins: phenotypic characterization showed pleiotropic effects on plant architecture similar to those known in rice (Wendt et al ). Heterotrimeric G proteins consist of three α, β and γ subunits, with the latter (also called AGG3 type) being present only in plants.…”

Extreme Suppression of Lateral Floret Development by a Single Amino Acid Change in the VRS1 Transcription Factor

“…In rice, a model grass plant, several major quantitative trait loci related to grain size, such as GW2, qSW5, GS5, OsSPL16, and An-1, have been identified (Song et al, 2007;Shomura et al, 2008;Li et al, 2011;Wang et al, 2012;Luo et al, 2013). However, little is known about the genetic basis of grain size in Triticeae species, including economically important crops such as wheat, barley, and rye (Secale cereale), except for TaGW2-A1, which is a rice GW2 ortholog in wheat (Simmonds et al, 2016), and HvDEP1 in barley, an ortholog of rice Dense and Erect Panicle 1 (Wendt et al, 2016).…”

How plants grow up

“…Potential partners linking meristem maintenance and stem elongation, especially in response to environmental cues, are heterotrimeric G‐proteins. For instance, a major dwarfing locus in rice, DENSE PANICLE1 (DEP1) and barley ( HvDEP1 ) encodes a Gγ subunit (Huang et al ; Wendt et al ; Xu et al ) while defective alleles in genes encoding the Gα subunit in rice (‘ daikoku ’ dwarf1 , Ashikari et al ; Fujisawa et al ), barley ( brachytic1 , Ito et al ; Braumann et al ), maize ( compact plant2 , ct2 , Bommert et al ) and Arabidopsis ( gpa1 , Ullah et al ) confer compact shoots due to reduced axial proliferation. In rice, DWARF1 interacts with GA and BR signaling to control height (Ashikari et al ; Oki et al ).…”