Suppression of stem rust resistance in the hexaploid wheat cv. Canthatch by chromosome 7DL

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.

Genome ◽  
1993 ◽  
Vol 36 (2) ◽  
pp. 289-293 ◽  
Author(s):  
P. L. Dyck

The Canadian common wheat (Triticum aestivum L.) cultivar 'Roblin' is resistant to both leaf rust (Puccinia recondita Rob. ex. Desm.) and stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. and E. Henn.). To study the genetics of this resistance, 'Roblin' was crossed with 'Thatcher', a leaf rust susceptible cultivar, and RL6071, a stem rust susceptible line. A set of F6 random lines was developed from each cross. The random lines and the parents were grown in a field rust nursery artificially inoculated with a mixture of P. recondita and P. graminis isolates and scored for rust reaction. The same material was tested with specific races of leaf rust and stem rust. These data indicated that 'Roblin' has Lr1, Lr10, Lr13, and Lr34 for resistance to P. recondita and Sr5, Sr9b, Sr11, and possibly Sr7a and Sr12 for resistance to P. graminis. In a 'Thatcher' background, the presence of Lr34 contributes to improve stem rust resistance, which appears also to occur in 'Roblin'.Key words: Triticum aestivum, wheat, leaf rust resistance, stem rust resistance.


Genome ◽  
1987 ◽  
Vol 29 (3) ◽  
pp. 467-469 ◽  
Author(s):  
P. L. Dyck

Backcross lines of gene LrT2 for resistance to leaf rust in the common wheat (Triticum aestivum L.) 'Thatcher' unexpectedly show improved resistance to stem rust compared with that of the recurrent parent. Genetic–cytogenetic evidence indicates that LrT2 is on chromosome 7D, which is known to carry the "suppressor" gene(s) that prevent the expression of stem rust resistance conferred by other genes in 'Canthatch'. Thus, LrT2 may be a nonsuppressing allele of the suppressor gene(s) or be closely linked to such an allele. LrT2 has been designated Lr34. Key words: Triticum, wheat, rust resistance.


2000 ◽  
Vol 80 (1) ◽  
pp. 53-63 ◽  
Author(s):  
D. R. Knott

Thatcher was the predominant wheat (Triticum aestivum L.) cultivar on the Canadian prairies in the 1950s. Until race 15B (TMH) of stem rust (Puccinia graminis pers. f. sp. tritici Eriks. & Henn.) became widespread, Thatcher had good resistance to stem rust, but was susceptible to leaf rust (P. recondita f. sp. tritici Rob. ex Desm.). Although genes for stem rust resistance have been identified in Thatcher, the inheritance of its resistance has never been fully understood. The objective of this research was to attempt to elucidate the inheritance of the resistance of Thatcher and to determine why it had a reputation as a poor parent for rust resistance. Over a period of 40 yr, crosses and backcrosses to a susceptible genotype and two sets of single seed descent (SSD) lines were studied. The second set of SSD lines was tested with isolates of six races of stem rust to which Thatcher is resistant. The data showed that Thatcher is a very heterogenous cultivar with individual plants differing widely in the genes for stem rust resistance that they carry. The inheritance of rust resistance varied greatly from race to race and was often quite complex. Either complementary genes or a gene plus a suppressor appeared to condition resistance to one race. Most genes gave resistance to only one race. The presence of Sr5, which Thatcher is known to have obtained from Kanred, was confirmed. Most of its many additional genes probably came from Iumillo durum wheat. Key words: Stem rust, Thatcher wheat, single seed descent


Genome ◽  
1990 ◽  
Vol 33 (4) ◽  
pp. 530-537 ◽  
Author(s):  
E. R. Kerber ◽  
P. L. Dyck

A partially dominant gene for adult-plant leaf rust resistance together with a linked, partially dominant gene for stem rust resistance were transferred to the hexaploid wheat cultivar 'Marquis' from an amphiploid of Aegilops speltoides × Triticum monococcum by direct crossing and backcrossing. Pathological evidence indicated that the alien resistance genes were derived from Ae. speltoides. Differential transmission of the resistance genes through the male gametes occurred in hexaploid hybrids involving the resistant 'Marquis' stock and resulted in distorted segregation ratios. In heterozygotes, pairing between the chromosome arm with the alien segment and the corresponding arm of the normal wheat chromosome was greatly reduced. The apparent close linkage between the two resistance genes, 3 ± 1.07 crossover units, was misleading because of this decrease in pairing in the presence of the 5B diploidizing mechanism. The newly identified gene for adult-plant leaf rust resistance, located on chromosome 2B, is different from adult-plant resistance genes Lr12, Lr13, and Lr22 and from that in the hexaploid accession PI250413; it has been designated Lr35. It is not known whether the newly transferred gene for stem rust resistance differs from Sr32, also derived from Ae. speltoides and located on chromosomes 2B.Key words: hexaploid, Triticum, Aegilops, aneuploid, Puccinia graminis, Puccinia recondita.


Plant Disease ◽  
2021 ◽  
Author(s):  
Tianya Li ◽  
Yiwei Xu ◽  
Xue Zhang ◽  
Xian Xin Wu ◽  
Yazhao Zhang ◽  
...  

Oat stem rust, caused by Puccinia graminis f. sp. avenae (Pga), is one of the most devastating diseases of oat. The most cost-effective and eco-friendly strategy to control this disease is the use of resistant cultivars. However, P. graminis f. sp. avenae can overcome the resistance of cultivars by rapidly changing its virulence. Thus, information on the virulence of P. graminis f. sp. avenae populations and resistance of cultivars is critical to control the disease. The current study was conducted to monitor the virulence composition and dynamics in the P. graminis f. sp. avenae population in China and to evaluate resistance of oat cultivars. Oat leaves naturally infected by P. graminis f. sp. avenae were collected during 2018 and 2019 and 159 isolates were derived from single uredinia. The isolates were tested on 12 international differential lines, and eight races, TJJ, TBD, TJB, TJD, TJL, TJN, TGD, and TKN, were identified for the first time in China. The predominant race was TJD, virulent against Pg1, Pg2, Pg3, Pg4, Pg8, Pg9, and Pg15, accounting for 35.8% and 37.8% in 2018 and 2019, respectively. The sub-predominant races were TJN (30.2% in 2018, 28.3% in 2019) and TKN (20.8% in 2018, 12.3% in 2019). All isolates were virulent to Pg1, Pg2, Pg3, and Pg4, and avirulent to Pg6 and Pg16. The three predominant races (TJD, TJN, and TKN) were used to evaluate resistance in 30 Chinese oat cultivars at the seedling and adult-plant stages. Five cultivars, Bayan 1, Baiyan 2, Baiyan 3, Baiyan 5, and Baiyan 9, were highly resistant to the three races at both seedling and adult-plant stages. The results of the virulences and frequencies of P. graminis f. sp. avenae races and the resistant cultivars will be useful in understanding the pathogen migration and evolution and for breeding oat cultivars with stem rust resistance.


1986 ◽  
Vol 28 (1) ◽  
pp. 12-16
Author(s):  
D. R. Knott

Studies were done in an attempt to determine the inheritance of adult plant resistance to stem rust (Puccinia graminis f. sp. tritici Eriks. and E. Henn.) in the wheat (Triticum aestivum L.) cultivars 'Hope' and 'Thatcher'. 'Chinese Spring' substitution lines carrying individual chromosomes from 'Hope' and 'Thatcher' were tested in field rust nurseries, three times each with races 15B-1 and 56, and twice with multirace mixtures. In 1976 it was found that the date of heading often had a significant effect on rust severity, with early lines showing less rust. In 1977 and 1984 the lines were divided into three groups based on maturity and were planted on three dates about 10 days apart to make heading dates more uniform. The data indicate that 'Hope' has genes for resistance to race 56 on chromosomes 3B (Sr2) and 4D, and to a multirace mixture on 1B, 3B, and 7B. 'Thatcher' possibly has genes for resistance to race 56 on chromosomes 6A and 3B (Sr12). The results show that the resistance of both cultivars is complex and most genes have only small effects.Key words: Triticum, Puccinia, rust resistance, substitution lines.


1975 ◽  
Vol 17 (4) ◽  
pp. 667-674 ◽  
Author(s):  
P. L. Dyck ◽  
G. J. Green

The genetics of resistance to stem rust (Puccinia graminis tritici) was investigated in wheat (Triticum aestivum L.) cultivars Romany, Es.P 518/9, Bonny and Tama that are resistant to many races in both Canada and Kenya. Seedling resistance in the four cultivars to 12 Canadian races is controlled primarily by previously identified genes. The results indicate that the cultivars have the following genes: Romany — Sr5, Sr6, Sr7a, Sr9b and SrW; Es.P 518/9 — Sr5, Sr6, Sr7a, Sr8, Sr9b, SrW and possibly Sr17; Bonny — Sr6 and Sr11; and Tama — Sr6 and Sr8. Gene SrW confers moderate resistance and is also present in the cultivar Webster.


2009 ◽  
Vol 89 (6) ◽  
pp. 1003-1008
Author(s):  
D R Knott

The common wheat (Triticum aestivum L.) cultivar Thatcher has resistance to many of the older races of stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & Henn.). Several genetic studies have shown that its resistance is complex in inheritance. To attempt to clarify the inheritance, 28 lines, each believed to carry a single resistance gene from Thatcher, were developed. The lines were tested with 13 races of stem rust. They fell into 13 types with resistance to from 1 to 11 races. Of the five genes previously identified in Thatcher, only two, Sr9g, and Sr12, were present in the lines. Four lines carried named genes, Sr6, Sr7a, Sr8a and S9d, which had not previously been detected in Thatcher. Thatcher is resistant to 8 of the 13 races. At least one line was resistant to each of the 13 races, including the five to which Thatcher is susceptible. Eleven of the 13 types of lines were resistant to race MCCD to which Thatcher is resistant. Seven of the types were resistant to race TMRT(15B-1) to which Thatcher is susceptible. Clearly, the inheritance of resistance in Thatcher is very complex and involves a considerable number of genes. It carries a surprising number of genes that appear to be hidden by the presence of suppressor genes or transposons.Key words: Common wheat, Triticum aestivum, Puccinia graminis, suppressors, tansposons


1977 ◽  
Vol 19 (1) ◽  
pp. 75-79 ◽  
Author(s):  
D. R. Knott ◽  
J. Dvořák ◽  
J. S. Nanda

A stem rust resistant wheat-Agropyron derivative obtained from Dr. F. X. Laubscher was crossed and backcrossed to Triticum aestivum L. cv. Marquis to determine the inheritance of its resistance to stem rust. Resistance proved to be carried on an Agropyron chromosome. A substitution line was obtained in which the Agropyron chromosome had replaced wheat chromosome 7D. The Agropyron chromosome compensates well for 7D in both plants and gametes and must, therefore, be homoeologous with the chromosomes of group 7. It is homologous with chromosome 7el1, the Agropyron chromosome carrying leaf rust resistance in Agrus, and it is, therefore, designated 7el2. Like 7el1 it carries a gene that results in a high level of yellow pigment in the flour. The frequent occurrence of genes for rust resistance on Agropyron chromosomes of homoeologous group 7 suggests that they may be related by descent.


Genome ◽  
1989 ◽  
Vol 32 (5) ◽  
pp. 932-933 ◽  
Author(s):  
D. R. Knott

A type of dwarfism found in crosses involving the wheat (Triticum aestivum L.) cultivar Webster and a stem rust (Puccinia graminis tritici Erik. &Henn.) susceptible line, LMPG, proved to be due to a dominant gene from cv. Webster and a recessive gene from LMPG. The dominant gene is closely linked to the gene Sr30, which conditions stem rust resistance in cv. Webster and is on chromosome 5D. The dwarf plants have short, dark green, stiff leaves and rarely develop more than two leaves before dying.Key words: dwarfism, Triticum aestivum, Puccinia graminis tritici, stem rust.


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