The location of major genes and associated quantitative trait loci on chromosome arm 5BL of wheat

Abstract

Chromosome 5B of bread wheat is known to carry two major genes giving rise to genetic disorders, Ne1 for hybrid necrosis and Vg for winter variegation. Additionally, in many european winter wheat varieties this chromosome is represented in a translocated form, with 5BL-7BL, 5BL-7BS chromosomes rather than the normal 5B and 7B forms of the standard variety Chinese Spring. Genetic analysis has been carried out to map these genes and the translocation break point, and to investigate their pleiotropic effects or those of linked quantitative trait loci (qtl) for economically important characters. This was facilitated by the development of single chromosome recombinant lines between a normal and translocated karyotype, and growing these in field experiments over two seasons. There was differential segregation in favour of the translocated karyotype in the population of recombinant lines. Linkage analysis revealed that the two morphological markers and the isozyme locus Ibf-B1 were located on the long arm of 5B with a gene order of: breakpoint - Ne1 - Vg - Ibf-B1. Analysis of quantitative characters using these genes as landmarks showed pleiotropic effects of Ne1 or effects of tightly linked qtl on most of the quantitative characters related to grain yield. An additional qtl determining spikelet and grain number/ear appeared to be linked to the centromere. Effects on ear emergence time were associated with both Ne1 and Vg, and these interacted with environments. Similarly, effects on plant height were associated with Ne1 and Vg. In addition, there was a further unlocated locus (loci) for height acting independently of the markers.

The control of adult‐plant resistance to yellow rust by the translocated chromosome 5BS‐7BS of bread wheat

“…In the Fi monosomic hybrid resulting from this cross, the 5BS-7BS chromosome is lacking and a trivalent is formed at meiosis with the configuration 5BS-5BL/5BL-7BL/7BL-7BS in which the 5BS and 7BS arms from the donor variety are left unpaired and therefore cannot undergo recombination. Because the translocation is large and involves a breakpoint at or very close to the centromere (Miura et al 1992), this trivalent is usually found in about 98% of metaphase cells, and normally disjoins with the 5BS-5BL and 7BL-7BS chromosomes going to one of the daughter cells and the 5BL-7BL chromosome to the other. In the backcross generations, the same chromosomal configuration is maintained until the final selfing when, because disomics are extracted, the gametes contributing to the zygote must each have the normal 5BS-5BL and 7BS-7BL chromosomes.…”

“…The translocation is an old one and can be traced to the variety 'Noe', which appeared in France in the latter part of the 19th century and probably has Russian origins (Lupton 1987). Miura et al (1992) found that the translocation was transmitted preferentially from plants in which it was heterozygous. They also found some evidence for a yield advantage associated with the 5BL arm.…”

Discovery of Consistent QTLs of Wheat Spike-Related Traits under Nitrogen Treatment at Different Development Stages

“…Some major QTLs for important yield-related traits other than SLl have been reported. For example, QTLs have been identified on chromosome 5B that affect spikelet number per spike and Gns (Miura et al, 1992 ), and Börner et al ( 2002 ) detected major QTLs on chromosomes 2DS, 4AL, and 5AL for Gns and grain weight per spike by studying a BC 2 F 1 population. In addition, eight QTLs on chromosomes 1D, 2A, 3D, 6A, 7A, and 7D for Gns have been found (Huang et al, 2004 ), and Li et al ( 2007 ) identified five QTLs for Ssn on chromosomes 1A, 4A, 6B, 7A, and 7D and five QTLs for Fsn on chromosomes 2A, 5D, 6B, and 7D using an RIL population.…”

Molecular genetic analysis of five spike-related traits in wheat using RIL and immortalized F2 populations

“…Law (1965Law ( , 1966 proposed to employ chromosome substitution lines or recombinant inbred chromosome lines to determine the genetic factors that aVect quantitative traits. Using such a strategy coupled with genetic markers, loci for yield-related traits of wheat have been assigned to chromosomes 3A (Shah et al 1999;Campbell et al 2003), 4A (Araki et al 1999), 5A (Snape et al 1985;Kato et al 2000), 5B (Miura et al 1992), and 7B (Law 1967). Berke et al (1992) explored quantitative trait loci (QTL) aVecting seven agronomical traits using a complete set of reciprocal chromosome substitutions between wheat cultivars 'Wichita' and 'Cheyenne'.…”