The relationships between the dwarfing genes of wheat and rye

Börner, Andreas; Plaschke, Jens; Korzun, Viktor; Worland, A. J.

doi:10.1007/bf00015721

Cited by 154 publications

(116 citation statements)

References 30 publications

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“…Six additional alleles at Rht-B1 and Rht-D1 have been identified by genetic mapping, four on chromosome 4B and two on chromosome 4D, which produce dwarfs with a broad range of plant height ( Fig. 1; Gale and Youssefian, 1985;Borner et al, 1996;Flintham et al, 1997). For example, the Rht-B1b and Rht-D1b alleles produce only about a 20% reduction in height, while Rht-B1c and Rht-D1c are about half the size of the appropriate tall controls (Hoogendoorn et al, 1990;Flintham et al, 1997).…”

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Molecular Characterization ofRht-1Dwarfing Genes in Hexaploid Wheat

et al. 2011

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The introduction of the Reduced height (Rht)-B1b and Rht-D1b semidwarfing genes led to impressive increases in wheat (Triticum aestivum) yields during the Green Revolution. The reduction in stem elongation in varieties containing these alleles is caused by a limited response to the phytohormone gibberellin (GA), resulting in improved resistance to stem lodging and yield benefits through an increase in grain number. Rht-B1 and Rht-D1 encode DELLA proteins, which act to repress GA-responsive growth, and their mutant alleles Rht-B1b and Rht-D1b are thought to confer dwarfism by producing more active forms of these growth repressors. While no semidwarfing alleles of Rht-A1 have been identified, we show that this gene is expressed at comparable levels to the other homeologs and represents a potential target for producing novel dwarfing alleles. In this study, we have characterized additional dwarfing mutations in Rht-B1 and Rht-D1. We show that the severe dwarfism conferred by Rht-B1c is caused by an intragenic insertion, which results in an in-frame 90-bp insertion in the transcript and a predicted 30-amino acid insertion within the highly conserved amino-terminal DELLA domain. In contrast, the extreme dwarfism of Rht-D1c is due to overexpression of the semidwarfing Rht-D1b allele, caused by an increase in gene copy number. We show also that the semidwarfing alleles Rht-B1d and Rht-B1e introduce premature stop codons within the amino-terminal coding region. Yeast two-hybrid assays indicate that these newly characterized mutations in Rht-B1 and Rht-D1 confer "GA-insensitive" dwarfism by producing DELLA proteins that do not bind the GA receptor GA INSENSITIVE DWARF1, potentially compromising their targeted degradation.

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Molecular Characterization ofRht-1Dwarfing Genes in Hexaploid Wheat

et al. 2011

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“…D1 encodes a putative heterotrimeric G protein ␣ -subunit (Ashikari et al, 1999;Ueguchi-Tanaka et al, 2000), and PKL encodes a chromatin remodeling factor (Ogas et al, 1999). Dominant and semidominant GA-insensitive mutants include the gainof-function gibberellin insensitive ( gai-1 ) allele in Arabidopsis (Koornneef et al, 1985), D8 and D9 in maize (Phinney, 1956), reduced height ( Rht ) mutants in wheat (Borner et al, 1996), and short internodes ( shi ) in Arabidopsis (Fridborg et al, 1999). shi encodes a putative zinc finger protein (Fridborg et al, 1999).…”

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Arabidopsis RGL1 Encodes a Negative Regulator of Gibberellin Responses

2002

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In Arabidopsis, the DELLA subfamily of GRAS regulatory genes consists of GAI , RGA , RGA-LIKE1 ( RGL1 ), RGL2 , and RGL3 . GAI and RGA are known to be negative regulators of gibberellin (GA) responses. We found that RGL1 is a similar repressor of GA responses, as revealed by RGL1 gain-of-function and loss-of-function phenotypes. Repression of GA responses in Arabidopsis was conferred by a dominant 35S-rgl1 transgene carrying a DELLA domain deletion analogous to the GA-insensitive gai-1 mutation. As in GA-deficient Arabidopsis, the transgenic plants were dark green dwarfs with underdeveloped trichomes and flowers. Expression levels of GA4 , a feedback-regulated GA biosynthetic gene, were increased correspondingly. Conversely, a loss-of-function rgl1 line had reduced GA4 expression and exhibited GA-independent activation of seed germination, leaf expansion, flowering, stem elongation, and floral development, as detected by resistance to the GA biosynthesis inhibitor paclobutrazol. RGL1 plays a greater role in seed germination than do GAI and RGA . The expression profile of RGL1 differed from those of the four other DELLA homologs. RGL1 message levels were predominant in flowers, with transcripts detected in developing ovules and anthers. As with RGA, green fluorescent protein (GFP)-tagged RGL1 protein was localized to the nucleus, but unlike GFP-RGA, there was no degradation after GA treatment. These findings indicate that RGL1 is a partially redundant, but distinct, negative regulator of GA responses and suggest that all DELLA subfamily members might possess separate as well as overlapping roles in GA signaling. INTRODUCTIONGibberellins (GAs) are a large family of tetracyclic diterpenoid compounds, many of which play important roles in plant growth and development (Hooley, 1994;Swain and Olszewski, 1996). Bioactive GAs are known to promote diverse processes, including seed germination, leaf expansion, shoot/stem elongation, floral initiation, floral organ development, and fruit development (Hooley, 1994;Swain and Olszewski, 1996). Mutants in GA biosynthesis have helped to determine the GA biosynthesis pathway (Hedden and Phillips, 2000;Yamaguchi and Kamiya, 2000), but less is known at present about the GA signal transduction pathway. A receptor for GA has been localized to the plasma membrane, but the identity of the receptor remains unknown (Gilroy and Jones, 1994). Biochemical and pharmacological data have indicated that Ca 2 ϩ , calmodulin, cyclic GMP, heterotrimeric G proteins, GAMYB, and protein kinases all are involved in GA signaling (Bethke and Jones, 1998;Lovegrove and Hooley, 2000;Sun, 2000).Genes involved in GA signal transduction have been uncovered through GA response mutants. These mutants are either GA-insensitive dwarfs or constitutive GA response mutants (Sun, 2000). The GA-insensitive dwarfs resemble GA-deficient mutants, but they are not rescued by GA treatment. They typically exhibit compact, dark green leaves, inhibition of seed germination, delay of flowering, and abnormal flower development...

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“…However, only 4 or 5 dwarfing genes of these mutations have been widely used (Börner et al, 1993;Ahmad and Sorrells, 2002). Among these major dwarfing genes, the semi-dwarfing alleles Rht-B1b (formerly Rht1) and Rht-D1b (formerly Rht2) are widely used in breeding programs (Gale and Youssefian, 1985;Börner et al, 1996).…”

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Characterization and molecular mapping of a dwarf mutant in wheat

Jin

Sun

Li³

et al. 2013

Genet. Mol. Res.

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ABSTRACT.A spontaneous dwarf mutant of wheat was found in an F 5 generation line derived from a cross between Huamai No. 9 and Een No. 1 in 1998; it was named Huaai 01. We characterized the genetic pattern of Huaai 01 and mapped the gene controlling the dwarf trait. This dwarf mutant was found insensitive to exogenous gibberellic acid treatment, based on the length of the first leaf and the coleoptile at the seedling stage, suggesting that it plays a crucial role in the gibberellin response pathway. Genetic analysis revealed that a single gene that is partially recessive controls the dwarf phenotype in Huaai 01. We named the dwarfing gene Rht-B2. Simple sequence repeats (SSR) were examined as identifying markers linked to the Rht-B2 gene in an F 2 population. We screened 904 pairs of primers and identified 5 SSR markers linked to the Rht-B2 gene. Two markers, barc1096 and xgwm495, were located on the flanking region of the Rht-B2 gene at genetic distances of 2.9 and 3.3 cM, respectively. Based on published SSR linkage data for wheat, the Rht-B2 gene was mapped to the long arm of chromosome 4B. This identification and characterization of the Rht-B2 dwarfing gene will facilitate its utilization in wheat breeding.

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The relationships between the dwarfing genes of wheat and rye

Cited by 154 publications

References 30 publications

Molecular Characterization ofRht-1Dwarfing Genes in Hexaploid Wheat

Molecular Characterization ofRht-1Dwarfing Genes in Hexaploid Wheat

Arabidopsis RGL1 Encodes a Negative Regulator of Gibberellin Responses

Characterization and molecular mapping of a dwarf mutant in wheat

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