Expression level of a gibberellin 20-oxidase gene is associated with multiple agronomic and quality traits in barley

Abstract

The use of dwarfing genes has resulted in the most significant improvements in yield and adaptation in cereal crops. The allelic dwarfing gene sdw1/denso has been used throughout the world to develop commercial barley varieties. The sdw1 gene has never been used successfully for malting barley, but only for a large number of feed varieties. One of the gibberellin 20-oxidase genes (Hv20ox₂) was identified as the candidate gene for sdw1/denso. Semi-quantitative real-time RT-PCR revealed that Hv20ox₂ was expressed at different levels in various organs of barley. Transcriptional levels were reduced in leaf blade, sheath, stem and rachis tissue in the barley variety Baudin with the denso gene. Subsequently, the relative expression levels of Hv20ox₂ were determined by quantitative real-time RT-PCR in a doubled haploid population and mapped as a quantitative trait. A single expression quantitative trait locus (eQTL) was identified and mapped to its structural gene region on chromosome 3H. The eQTL was co-located with QTLs for yield, height, development score, hectolitre weight and grain plumpness. The expression level of Hv20ox₂ was reduced fourfold in the denso mutant, but around 60-fold in the sdw1 mutant, compared to the control variety. The reduced expression level of Hv20ox₂ enhanced grain yield by increasing the number of effective tillers, but had negative effects on grain and malting quality. The sdw1 gene can be used only in feed barley due to its severe reduction of Hv20ox₂ expression. The gene expression marker for Hv20ox₂ can be used to distinguish different alleles of sdw1/denso.

Sorghum Dw1, an agronomically important gene for lodging resistance, encodes a novel protein involved in cell proliferation

“…For example, mutations of semi-dwarf1 (sd1) in rice1923 and Reduced height (Rht) in wheat20, which encode a GA biosynthesis enzyme and a dominant suppressor protein of GA signal transduction, respectively, have been widely used to improve lodging resistance in these crops, resulting in the success of the “green revolution”. It has also been reported that the semi-dwarfism of barley, sdw1/denso , widely introgressed into cultivars grown in Europe, probably results from a defect in an ortholog of rice SD1 242526. That GA-related mutations have been used for improving lodging resistance in rice, wheat, and barley, demonstrates the importance of decreasing the GA level, or sensitivity to GA, in reducing plant heights.…”

Arabidopsis semidwarfs evolved from independent mutations in GA20ox1 , ortholog to green revolution dwarf alleles in rice and barley

“…This lack of effect on seed production is probably due to expression of GA20ox paralogs, mainly GA20ox2 (8). Similarly, GA20ox2 mutations in rice and barley do not display tradeoffs (5,6,27). By contrast, mutations in early steps of GA biosynthesis have been associated with negative pleiotropic effects, such as the absence of seed germination shown by ga1 null mutants or the reduced fertility and altered flower development observed even in leaky GA1 alleles (13).…”

Marker development using SLAF-seq and whole-genome shotgun strategy to fine-map the semi-dwarf gene ari-e in barley

“…Therefore, sdw1/denso is expressed all of the tissues and affects many developmental processes through GA level [7, 8]. ari-e also reduces plant height and is related with lots of agronomic traits, such as erect juvenile growth habit, earliness, compact inflorescene, short awns, small seed size and cell size reduction in leaf blades [19, 24, 25].…”

“…This indicated that ari-e may be involved in different developmental processes. Furthermore, reduced expression of HvGA20ox 2 was identified in various organs in denso semi-dwarf mutant compared with tall variety [7]. Rieu et al [69] reported that AtGA20ox 1 (also named as semi-dwarf gene ga5 ) was showed different expression in different tissues, and at different developmental stages.…”