Genetic analysis of the Group IV Rht LOCI in wheat.
type: CreativeWork
description: The introduction of the group IV semi-dwarf Rht alleles, Rht-B1b (formerly Rht1) and Rht-D1b (formerly Rht2) into bread wheat varieties from the donor line „Norin 10‟ that began in the 1960s was a major contributor to the „green revolution‟. Rht-B1b and Rht-D1b were characterised and cloned over a decade ago (Gale and Youssefian 1985; Peng et al. 1999), however the Rht-A1 locus has not been isolated and little is known regarding the genetic diversity of the group IV Rht loci or the genetic composition of the contiguous sequence surrounding Rht that was presumably introgressed into wheat varieties along with the dwarfing alleles. To investigate the contiguous region around Rht, a hexaploid wheat („Chinese Spring‟ (CS)) BAC library was screened using a PCR-based technique (Febrer et al. 2009). This identified several Rht-containing BAC clones, three of which (representing the A, B, and D genomes) were sequenced and found to contain one to two genes upstream of Rht in conserved order. Gene synteny was also highly conserved in rice, Brachypodium distachyon, sorghum, and maize. The previously unidentified Rht-A1 homoeologue was physically mapped to the long arm of chromosome 4A using aneuploid lines and mapped relative to genetic markers. To estimate genetic diversity, the entire coding regions of Rht-A1, Rht-B1, and Rht-D1 and the flanking regions (approximately 1800 bp 5‟ and 450 bp 3‟) were sequenced in 40 diverse wheat accessions. Little polymorphism and few haplotypes were identified on the A and D genomes, but on the B genome a relative abundance of haplotypes and polymorphism were present, including insertions (relative to CS) of 160 bp and 197 bp within 600 nucleotides of the ORF. The Rht-B1 insertions did not have a pronounced effect on RNA transcript level when assessed in seedlings. In an analysis of 368 lines from the INRA bread wheat core collection (BWCC) (Balfourier et al., 2007), lines with the Rht-B1 insertions were associated with reduced heights and re…
abstract: The introduction of the group IV semi-dwarf Rht alleles, Rht-B1b (formerly Rht1) and Rht-D1b (formerly Rht2) into bread wheat varieties from the donor line „Norin 10‟ that began in the 1960s was a major contributor to the „green revolution‟. Rht-B1b and Rht-D1b were characterised and cloned over a decade ago (Gale and Youssefian 1985; Peng et al. 1999), however the Rht-A1 locus has not been isolated and little is known regarding the genetic diversity of the group IV Rht loci or the genetic composition of the contiguous sequence surrounding Rht that was presumably introgressed into wheat varieties along with the dwarfing alleles. To investigate the contiguous region around Rht, a hexaploid wheat („Chinese Spring‟ (CS)) BAC library was screened using a PCR-based technique (Febrer et al. 2009). This identified several Rht-containing BAC clones, three of which (representing the A, B, and D genomes) were sequenced and found to contain one to two genes upstream of Rht in conserved order. Gene synteny was also highly conserved in rice, Brachypodium distachyon, sorghum, and maize. The previously unidentified Rht-A1 homoeologue was physically mapped to the long arm of chromosome 4A using aneuploid lines and mapped relative to genetic markers. To estimate genetic diversity, the entire coding regions of Rht-A1, Rht-B1, and Rht-D1 and the flanking regions (approximately 1800 bp 5‟ and 450 bp 3‟) were sequenced in 40 diverse wheat accessions. Little polymorphism and few haplotypes were identified on the A and D genomes, but on the B genome a relative abundance of haplotypes and polymorphism were present, including insertions (relative to CS) of 160 bp and 197 bp within 600 nucleotides of the ORF. The Rht-B1 insertions did not have a pronounced effect on RNA transcript level when assessed in seedlings. In an analysis of 368 lines from the INRA bread wheat core collection (BWCC) (Balfourier et al., 2007), lines with the Rht-B1 insertions were associated with reduced heights and re…
author: Wilhelm, Edward
language: en
date published: 2011-06
date modified: 2026-07-24T02:12:03Z
provider: University of East Anglia
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of East Anglia