Allelic Variation at the Dwarfing Gene Rht8 Locus and Its Significance in International Breeding Programmes

Worland, A. J.; Sayers, E. J.; Korzun, Viktor

doi:10.1007/978-94-017-3674-9_100

Cited by 37 publications

(70 citation statements)

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“…Second, the homozygous lines are completely infertile. Similar unintended negative consequences on growth, pathogen resistance or yield (Worland et al, 2001;Knopf et al, 2008) have been observed previously for other dwarfing alleles, and these can restrict their use in breeding programmes. In wheat, multiple alleles of just three dwarfing genes are used to modify plant stature in commercial lines (Knopf et al, 2008).…”

Section: Discussionmentioning

confidence: 53%

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A T‐DNA mutation in the RNA helicase eIF4A confers a dose‐dependent dwarfing phenotype in Brachypodium distachyon

et al. 2011

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SUMMARYIn a survey of the BrachyTAG mutant population of Brachypodium distachyon, we identified a line carrying a T-DNA insertion in one of the two eukaryotic initiation factor 4A (eIF4A) genes present in the nuclear genome. The eif4a homozygous mutant plants were slow-growing, and exhibited reduced final plant stature due to a decrease in both cell number and cell size, consistent with roles for eIF4A in both cell division and cell growth. Hemizygous plants displayed a semi-dwarfing phenotype, in which stem length was reduced but leaf length was normal. Linkage between the insertion site and phenotype was confirmed, and we show that the level of eIF4A protein is strongly reduced in the mutant. Transformation of the Brachypodium homozygous mutant with a genomic copy of the Arabidopsis eIF4A-1 gene partially complemented the growth phenotype, indicating that gene function is conserved between mono-and dicotyledonous species. This study identifies eIF4A as a novel dose-dependent regulator of stem elongation, and demonstrates the utility of Brachypodium as a model for grass and cereals research.

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Section: Discussionmentioning

confidence: 53%

“…As in many dwarf and semi-dwarf cereals (Worland et al, 2001), reduction in eIF4A is associated with reduction in grain yield. Grain development in eif4a mutant lines is affected in two ways.…”

Section: Discussionmentioning

confidence: 99%

A T‐DNA mutation in the RNA helicase eIF4A confers a dose‐dependent dwarfing phenotype in Brachypodium distachyon

et al. 2011

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“…(Table 6). While all CIMMYT semidwarf bread wheats are expected to carry Rht-B1b or Rht-D1b, it was shown that a height-promoting allele at the Rht8 locus is also frequently present in CIMMYT wheats, and it is speculated that this allele might confer an adaptive advantage by partially counteracting the dramatic effects of Rht-B1b and Rht-D1b (Worland et al 2001).…”

Section: Discussionmentioning

confidence: 99%

Association Analysis of Historical Bread Wheat Germplasm Using Additive Genetic Covariance of Relatives and Population Structure

et al. 2007

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Linkage disequilibrium can be used for identifying associations between traits of interest and genetic markers. This study used mapped diversity array technology (DArT) markers to find associations with resistance to stem rust, leaf rust, yellow rust, and powdery mildew, plus grain yield in five historical wheat international multienvironment trials from the International Maize and Wheat Improvement Center (CIMMYT). Two linear mixed models were used to assess marker-trait associations incorporating information on population structure and covariance between relatives. An integrated map containing 813 DArT markers and 831 other markers was constructed. Several linkage disequilibrium clusters bearing multiple host plant resistance genes were found. Most of the associated markers were found in genomic regions where previous reports had found genes or quantitative trait loci (QTL) influencing the same traits, providing an independent validation of this approach. In addition, many new chromosome regions for disease resistance and grain yield were identified in the wheat genome. Phenotyping across up to 60 environments and years allowed modeling of genotype 3 environment interaction, thereby making possible the identification of markers contributing to both additive and additive 3 additive interaction effects of traits.A useful new tool for crop genetic improvement is the identification of polymorphic markers associated with phenotypic variation for important traits by means of linkage disequilibrium (LD) between loci ( Thornsberry et al. 2001;Flint-Garcia et al. 2003). A major advantage of this approach over conventional linkage mapping is that it does not require the timeconsuming and expensive generation of specific genetic populations. LD is determined by the physical distance of the loci across chromosomes and has proven useful for dissecting complex traits because it offers fine-scale mapping due to the inclusion of historical recombination (Lynch and Walsh 1998). However, false positive correlation between markers and traits can arise in the absence of physical proximity due to population structure caused by admixture, mating system, and genetic drift or by artificial or natural selection during evolution, domestication, or plant improvement ( Jannink and Walsh 2002). False associations can also be caused by alleles occurring at very low frequencies in the initial population (Breseghello and Sorrells 2006a,b). These factors create LD between loci that are not physically linked and cause a high rate of false positives when relating polymorphic markers to phenotypic trait variation. Thus, separating LD due to physical linkage from LD due to population structure is a critical prerequisite in association analyses.Population structure can be quantified using Bayesian analysis, which has been effective for assigning individuals to subpopulations (Q matrix) using unlinked markers (Pritchard et al. 2000). Other multivariate statistical analyses such as classification (clustering) and ordination (scaling) can al...

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“…Nalazi se 0,6 cM distalno od Rht8 gena na kratkom kraku 2D hromozoma . Analizom preko 800 sorti pšenice poreklom iz 20 različitih zemalja, utvrđeno je da su u lokusu Xgwm261, alelne varijante od 165, 174 i 192 bp, bile zastupljene sa preko 90% (Worland et al 2001). Kobiljski et al (2006) su evaluacijom varijabilnosti mikrosatelitskog lokusa Xgwm261 kod 269 sorti i linija stvorenih u oplemenjivačkim centrima u Srbiji, utvrdili da 73,6% genotipova poseduje alel od 192 bp, 14,9% alel od 174 bp, 7% alel od 165 bp i 4,56% novi fragment veličine oko 200 bp.…”

Section: Rezultati I Diskusijaunclassified

“…1). Ovi aleli bili bi ekvivalentni fragmentima od 174 bp i 192 bp prethodno navedenih autora (Worland et al 2001, Kobiljski et al 2006), a razlike od 1 bp posledica su primene različitih sistema pri analizi fragmenata i kasnijoj obradi dobijenih rezultata. Statistički značajna asocijacija između markera GWM261 i vremena klasanja i cvetanja, ustanovljena u ovom radu, može biti rezultat veze ovog markera sa Ppd-D1 genom, koji prema Scarth and Law (1983) ima značajnu ulogu u determinisanju vremena klasanja kao odgovor na dužinu trajanja dana.…”

Section: Rezultati I Diskusijaunclassified

Marker-trait association analysis for heading and flowering time in wheat by Single Marker Regression

Trkulja¹,

Kondić‐Špika²,

Brbaklić³

et al. 2011

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Izvod: Dihaploidne mapirajuće populacije predstavljaju pogodan materijal za genetičku analizu lokusa koji utiču na ekspresiju kvantitativnih svojstava (QTL -Quantitative Trait Loci). U cilju detekcije lokusa koji su u vezi sa vremenom klasanja i cvetanja u našem agro-klimatskom regionu, u radu je analizirana alelna varijabilnost pet mikrosatelitskih lokusa (Xgwm18, Xgwm194, Xgwm261, Xpsp3071 i Xpsp3200) kod 177 linija dihaploidne populacije Savana/Renesansa. Pored toga, na oglednim poljima Instituta za ratarstvo i povrtarstvo u Novom Sadu u periodu [2003][2004][2005][2006][2007][2008]. rađena je fenotipska evaluacija ove mapirajuće populacije za navedene osobine. Metodom pojedinačne marker regresije detektovan je QTL u blizini lokusa Xgwm261, pomoću kog se moglo objasniti od 20,2% do 30,7% fenotipske varijabilnosti za vreme klasanja i 13,6% do 28,8% za vreme cvetanja, u svim analiziranim godinama. UvodKod klasičnih metoda oplemenjivanja biljaka, efi kasnost selekcije u velikoj meri zavisi od mogućnosti da se predvidi genotipska vrednost individua, na osnovu fenotipske analize i opaža-nja svojstava od agronomskog značaja. Imajući u vidu da se većina svojstava od značaja za oplemenjivače nalazi pod kontrolom velikog broja gena (tzv. kvantitativna svojstva), identifi kacija QTLova, bazirana isključivo na fenotipskoj selekciji, smatra se nemogućom (Eathington et al. 2007), naročito ako se uzme u obzir i uvek prisutna interakcija genotip/spoljna sredina, a koja je kod svojstava uslovljenih poligenima uvek karakterisana i različitim vrednostima heritabilnosti, tač-nije različitim udelom genotipske u ukupnoj fenotipskoj varijansi. Sa pojavom tehnika molekularnih markera osamdesetih godina prošlog veka, stvorene su mogućnosti za preciznu genetičku analizu i detekciju lokusa koji kontrolišu osobine, koje su deteminisane većim brojem gena. U odnosu na druge tehnike molekularnih markera, mikrosateliti pokazuju znatno viši nivo polimorfnosti i informativnosti pri proučavanju genoma heksaploidne pšenice (Ganal & Röder 2007).Dihaploidne populacije imaju veliki potencijal za identifi kaciju QTL-ova jer je usled visokog procenta homozigotnosti i jednostavnog održa-vanja omogućena njihova evaluacija u različitim godinama i različitim uslovima spoljašnje sredine. Istraživanja bazirana na kompjuterskim simulacijama demonstrirala su da dihaploidne populacije povećavaju efi kasnost marker asistirane selekcije (MAS -Marker Assisted Selection), kroz strategiju kombinovanja velikog broja gena sa minimalnim brojem marker testova (Howes et al. 1998).Vreme klasanja i cvetanja predstavlja glavnu odrednicu regionalne i sezonske adaptacije sorti pšenice. Prilagođenost se ogleda u izbegavanju niskih temperatura za vreme cvetanja (koje mogu da prouzrokuju mušku sterilnost), kao i visokih temperatura i suše u vreme nalivanja zrna. Stoga je razumevanje genetičke osnove vremena klasanja i cvetanja neophodan preduslov za stvaranje sorti

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Allelic Variation at the Dwarfing Gene Rht8 Locus and Its Significance in International Breeding Programmes

Cited by 37 publications

References 6 publications

A T‐DNA mutation in the RNA helicase eIF4A confers a dose‐dependent dwarfing phenotype in Brachypodium distachyon

A T‐DNA mutation in the RNA helicase eIF4A confers a dose‐dependent dwarfing phenotype in Brachypodium distachyon

Association Analysis of Historical Bread Wheat Germplasm Using Additive Genetic Covariance of Relatives and Population Structure

Marker-trait association analysis for heading and flowering time in wheat by Single Marker Regression

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