Overgrowth mutants determine the causal role of gibberellin GA2oxidaseA13 in Rht12 dwarfism of wheat

Abstract

The induced dwarf mutant Rht12 was previously shown to have agronomic potential to replace the conventional DELLA mutants Rht-B1b/Rht-D1b in wheat. The Rht12 dwarfing gene is not associated with reduced coleoptile length (unlike the DELLA mutants), and it is dominant, characteristics which are shared with the previously characterised dwarfing genes Rht18 and Rht14. Using the Rht18/Rht14 model, a GA 2-oxidase gene was identified in the Rht12 region on chromosome 5A. A screen for suppressor mutants in the Rht12 background identified tall overgrowth individuals that were shown to contain loss of function mutations in GA2oxidaseA13, demonstrating the role of this gene in the Rht12 dwarf phenotype. It was concluded that Rht12, Rht18 and Rht14 share the same height-reducing mechanism through the increased expression of GA 2-oxidase genes. Some of the overgrowth mutants generated in this study were semi-dwarf and taller than the original Rht12 dwarf, providing breeders with new sources of agronomically useful dwarfism.

Towards the replacement of wheat ‘Green Revolution’ genes

“…These drawbacks have incentivized the search for alternative dwarfing alleles that might combine an optimal reduction in final plant height without restricting coleoptile and seedling growth. To this end, researchers have identified a number of such alleles and have recently made progress in characterizing their mode of action ( Gasperini et al , 2012 ; Ford et al , 2018 ; Buss et al , 2020 ). To help evaluate the potential of these alleles for wheat breeding, carefully designed field experiments will be required.…”

“…This suggests that there may be other excellent candidate alleles among those already described that might similarly be subjected to expanded field testing to evaluate their value to breeding programs and wheat producers ( Box 1 ). These include independent GA-sensitive alleles such as Rht12 ( Sun et al , 2019 ; Buss et al , 2020 ) and Rht25 ( Mo et al , 2018 ), as well as TEOSINTE BRANCHED 1 , which was recently shown to regulate height and architecture ( Dixon et al , 2020 ).…”

“…In addition to characterizing known dwarfing loci, wheat researchers now have access to tools such as CRISPR/Cas9 [clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9] that can enhance allelic diversity by directly engineering genetic variation in specific target genes ( Zhang et al , 2020 ). As well as Rht18 , at least one other dwarfing locus ( Rht12 ) is associated with increased expression of a GA 2-oxidase gene ( Ford et al , 2018 ; Sun et al , 2019 ; Buss et al , 2020 ). Therefore, it may be possible to develop a range of valuable dwarfing alleles by inducing variation in the cis -regulatory regions of members of this multigene family.…”

Effect of Prohexadione-calcium on the Shoot Growth, Fruits, Endogenous Hormones and Expression of GA-related Genes in ‘Fuji’ Apple (Malus Domestica Borkh.)

“…During periods of vigorous growth, the transcription level is relatively high and the amount of bioactive GA synthesized was reduced in the absence of GA20ox and GA3ox. Similarly, overexpression of GA2ox degraded the bioactive GA in plants, resulting in a dwarfed phenotype [47][48][49] . In our study, we discovered that ProCa inhibit the elongation of long terminal shoots by decreasing the transcript level of GA3ox12 in almost all analysis times (Fig.…”

Association Analysis Revealed That TaPYL4 Genes Are Linked to Plant Growth Related Traits in Multiple Environment

“…During the “Green Revolution” of 1960s, the discovery of semi-dwarf genes led to a dramatic increase in wheat yields ( Peng et al, 1999 ; Saville et al, 2012 ). Despite many regulator genes of plant height were reported such as TaCOLD1 , Rht18 , and Rht12 ( Van De Velde et al, 2017 ; Dong et al, 2019 ; Buss et al, 2020 ; Tang et al, 2020 ), other important genes associated with wheat plant height remain to be identified. Combined with previous findings, exploiting the excellent genetic resources of wheat is the most economical and effective way to breed new varieties with higher grain yields.…”