TELOCENTRIC MAPPING IN HEXAPLOID WHEAT OF GENES FOR LEAF RUST RESISTANCE AND OTHER CHARACTERS DERIVED FROM AEGILOPS SQUARROSA

1974 ◽  
Vol 16 (1) ◽  
pp. 137-144 ◽  
Author(s):  
G. G. Rowland ◽  
E. R. Kerber

Telocentrics of hexaploid wheat, Triticum aestivum spp. vulgare cv. Chinese Spring, were used to establish the chromosome arm location and crossover distance from the centromere of genes controlling characters introduced into synthetic hexaploid wheat (2n = 42 = AABBDD) from Aegilops squarrosa (2n = 14 = DD). The chromosome arm location and the crossover distance from the centromere of each gene studied are as follows: synthetic hexaploid RL 5404 — brown glumes (Rg2), 1DL, 13.3 ± 3.3%; tenacious glumes (Tg), 2Dα, 39.4 ± 4.9%; inhibitor of waxy foliage (W21), 2Dα, 52.5 ± 5.0%; adult-plant leaf rust resistance (Lr22), 2Dα, 63.6 ± 4.8%; purple coleoptile (Rc3), 7DS, 10.3 ± 2.8%; synthetic hexaploid RL 5406 — Rg2, 1DL, 1.7 ± 1.0%; Tg, 2Dα, 42.9 ± 4.6%; W21, 2Dα, 58.9 ± 4.6%; Rc3, 7DS, 9.8 ± 2.8%. A gene for seedling leaf rust resistance (Lr21) found in RL 5406 is located on chromosome 1D.


1969 ◽  
Vol 11 (3) ◽  
pp. 639-647 ◽  
Author(s):  
E. R. Kerber ◽  
P. L. Dyck

The inheritance of seedling leaf rust resistance and several morphological characters derived from Aegilops squarrosa (2n = 14 = DD) was investigated in a synthetic hexaploid wheat. The hexaploid was obtained by combining the tetraploid component (2n = 28 = AABB) extracted from the common wheat cultivar Canthatch with Ae. squarrosa var. meyeri R.L. 5289.A major, partially dominant gene was identified that gives good resistance (type 0;1 reaction) to leaf rust races 1, 5, 9, 11, 15, 30, 58 and 126a. This gene was shown to be different from the resistance genes Lr1, Lr2, Lr3, Lr10, Lr16, Lr17 and Lr18. A minor second gene was also detected which gives resistance (type 2 reaction) to race 9 and slight resistance to some of the other races.Each of the characters purple coleoptile, non-waxy foliage, brown glumes, and non-free threshing (tenacious glumes) of the synthetic wheat was monogenically inherited. The gene for threshability may be different from other genetic systems known to affect this character. The gene for brown glumes was linked with the major gene for leaf rust resistance with a recombination value of 3.1 ± 1.1%. The genes for non-waxy foliage and non-free threshing were associated with an estimated linkage value of 15.1 ± 2.6%.The results effectively demonstrated the relative ease with which genetic variation may be incorporated into common hexaploid wheat from its ancestral diploid, Ae. squarrosa, by means of a synthetic hexaploid intermediary. The method avoids the difficulties and complications often encountered with the transfer of genes from more distantly related species which do not have a genome in common with T. aestivum.



1970 ◽  
Vol 12 (1) ◽  
pp. 175-180 ◽  
Author(s):  
P. L. Dyck ◽  
E. R. Kerber

The inheritance of adult-plant leaf rust resistance derived from Aegilops squarrosa was studied in a synthetic hexaploid wheat. The hexaploid was produced by combining the AABB component extracted from the common wheat cultivar Canthatch with Ae. squarrosa var. strangulata R.L. 5271 which has adult-plant resistance to several races of leaf rust. Resistance is conferred by a single, partially dominant gene that is inherited independently of Lr12 and L13, two previously identified genes for adult-plant leaf rust resistance. Although monogenic inheritance was observed, this gene must be influenced by the genetic background since its level of resistance was somewhat reduced during successive backcrosses to Thatcher.This new gene for adult-plant leaf rust resistance was linked with each of the genes for foliage waxiness and threshability with a recombination value of 15.6 ± 2.5% and 6.0 ± 1.5%, respectively. The genes for foliage waxiness and threshability were associated with an estimated linkage value of 17.4 ± 2.5%.



2019 ◽  
Author(s):  
Volker Mohler ◽  
Michael Schmolke ◽  
Friedrich J. Zeller ◽  
Sai L.K. Hsam

SummarySeedling resistance to leaf rust available in the synthetic hexaploid wheat line Syn137 was characterized by means of cytogenetic and linkage mapping. Monosomic analysis located a single dominant gene for leaf rust resistance on chromosome 5D. Molecular mapping not only confirmed this location but also positioned the gene to the distal part of the long arm of chromosome 5D. A test of allelism showed that the gene, tentatively named LrSyn137, is independent but closely linked to Lr1. It appears that Syn137 is occasionally heterogeneous for Lr1 since the analysis of the Lr1-specific marker RGA567-5 in the mapping population indicated the presence of Lr1. Syn137 represents another source of genetic variation that can be useful for the diversification of leaf rust resistance in wheat cultivars.



2019 ◽  
Vol 20 (10) ◽  
pp. 2445 ◽  
Author(s):  
Harsimardeep S. Gill ◽  
Chunxin Li ◽  
Jagdeep S. Sidhu ◽  
Wenxuan Liu ◽  
Duane Wilson ◽  
...  

Leaf rust caused by Puccinia triticina Eriks is one of the most problematic diseases of wheat throughout the world. The gene Lr42 confers effective resistance against leaf rust at both seedling and adult plant stages. Previous studies had reported Lr42 to be both recessive and dominant in hexaploid wheat; however, in diploid Aegilops tauschii (TA2450), we found Lr42 to be dominant by studying segregation in two independent F2 and their F2:3 populations. We further fine-mapped Lr42 in hexaploid wheat using a KS93U50/Morocco F5 recombinant inbred line (RIL) population to a 3.7 cM genetic interval flanked by markers TC387992 and WMC432. The 3.7 cM Lr42 region physically corresponds to a 3.16 Mb genomic region on chromosome 1DS based on the Chinese Spring reference genome (RefSeq v.1.1) and a 3.5 Mb genomic interval on chromosome 1 in the Ae. tauschii reference genome. This region includes nine nucleotide-binding domain leucine-rich repeat (NLR) genes in wheat and seven in Ae. tauschii, respectively, and these are the likely candidates for Lr42. Furthermore, we developed two kompetitive allele-specific polymorphism (KASP) markers (SNP113325 and TC387992) flanking Lr42 to facilitate marker-assisted selection for rust resistance in wheat breeding programs.



1980 ◽  
Vol 58 (12) ◽  
pp. 1347-1350 ◽  
Author(s):  
E. R. Kerber ◽  
G. J. Green

The nullisomic for chromosome 7D (2n = 40) of the hexaploid wheat cv. Canthatch (Triticum aestivum L., 2n = 42) was found to be resistant in both the seedling and adult-plant stages to several races of stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. and E. Henn) to which normal disomic Canthatch (2n = 42) was susceptible. Since ditelosomic 7DL (2n = 40 + tt) reacted in the same manner as Canthatch, it appears that a gene(s) is present on the long arm of chromosome 7D that suppresses resistance determined by other genes, probably on chromosomes of the A and B genomes. Evidence indicated that the suppressor was derived from the ancestral, diploid progenitor of common wheat, Aegilops squarrosa L., rather than by mutation at the hexaploid level. The results provide a genetic explanation for apparent failures of some attempts to transfer stem rust and leaf rust resistance to hexaploid wheat from diploid and tetraploid relatives.



1979 ◽  
Vol 59 (2) ◽  
pp. 499-501 ◽  
Author(s):  
P. L. DYCK

The gene for adult-plant resistance to race 9 of leaf rust (Puccinia recondita Rob. ex. Desm.) in the common wheat cultivar Thatcher (Triticum aestivum L.) was allelic to Lr22a, a gene for adult-plant leaf rust resistance previously transferred to hexaploid wheat from Aegilops squarrosa L. This gene, designated Lr22b, was linked with Tg, a gene for tenacious glumes, and W21, an inhibitor of waxy foliage, both known to be on chromosome arm 2Dα and linked with Lr22a.



2018 ◽  
Vol 108 (12) ◽  
pp. 1344-1354 ◽  
Author(s):  
Gerarda Beatriz Pinto da Silva ◽  
Camila Martini Zanella ◽  
José Antônio Martinelli ◽  
Márcia Soares Chaves ◽  
Colin W. Hiebert ◽  
...  

Leaf rust, caused by the fungal pathogen Puccinia triticina, is a major threat to wheat production in many wheat-growing regions of the world. The introduction of leaf rust resistance genes into elite wheat germplasm is the preferred method of disease control, being environmentally friendly and crucial to sustained wheat production. Consequently, there is considerable value in identifying and characterizing new sources of leaf rust resistance. While many major, qualitative leaf rust resistance genes have been identified in wheat, a growing number of valuable sources of quantitative resistance have been reported. Here we review the progress made in the genetic identification of quantitative trait loci (QTL) for leaf rust resistance detected primarily in field analyses, i.e., adult plant resistance. Over the past 50 years, leaf rust resistance loci have been assigned to genomic locations through chromosome analyses and genetic mapping in biparental mapping populations, studies that represent 79 different wheat leaf rust resistance donor lines. In addition, seven association mapping studies have identified adult plant and seedling leaf rust resistance marker trait associations in over 4,000 wheat genotypes. Adult plant leaf rust resistance QTL have been found on all 21 chromosomes of hexaploid wheat, with the B genome carrying the greatest number of QTL. The group 2 chromosomes are also particularly rich in leaf rust resistance QTL. The A genome has the lowest number of QTL for leaf rust resistance. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .



Crop Science ◽  
2018 ◽  
Vol 58 (1) ◽  
pp. 152-158 ◽  
Author(s):  
J. A. Kolmer ◽  
S. Chao ◽  
G. Brown-Guedira ◽  
U. Bansal ◽  
H. Bariana


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