THE INHERITANCE OF RUST RESISTANCE. II. THE INHERITANCE OF STEM RUST RESISTANCE IN SIX ADDITIONAL VARIETIES OF COMMON WHEAT

1957 ◽  
Vol 37 (3) ◽  
pp. 177-192 ◽  
Author(s):  
D. R. Knott

The inheritance of resistance to races 15B and 56 of stem rust was studied in the varieties Africa No. 43, Kenya C9906, Kenya 338.AC.2.E.2, Egypt Na101, Veadeiro and Red Egyptian type (P.I. 170910). Each variety was analysed genetically on the basis of data obtained from a backcross to the rust susceptible variety Marquis. The interrelationships of the genes in the varieties were determined from diallel crosses. With the exception of Veadeiro, the varieties all carried various combinations of genes reported in the first paper of this series. Veadeiro has a mature plant resistance to race 15B which is probably conditioned by two additive genes not previously noted.

1957 ◽  
Vol 37 (4) ◽  
pp. 366-384 ◽  
Author(s):  
D. R. Knott

The inheritance of resistance to races 15B and 56 of stem rust was studied in the varieties Kenya 58, Kenya 117A, Kenya C9906, Kenya 338.AC.2.E.2, Kenya Governor, Kenya B286, Kenya 291.J.1.I.1, Kenya 321.BT.1.B.1 and Kenya 350.AD.9.C.2. The first five varieties had been studied previously and crosses involving them were not repeated. The genetic analysis of the varieties was based on diallel crosses and backcrosses to a susceptible parent, Marquis.All nine varieties proved to carry Sr7, a gene which conditions resistance to race 15B. Four varieties, Kenya 58, Kenya C9906, Kenya 291 and Kenya 350, carry the gene Sr6, which conditions a hypersensitive reaction to both race 15B and race 56. In addition, four of the varieties carry Sr9 and five carry Sr10, two genes which produce moderate resistance to race 56. Kenya 338.AC.2.E.2 carries two additional dominant, complementary genes, Sr11 and Sr12, which condition resistance to race 56.The genes, Sr9, Sr10, Sr11 and Sr12 are important modifiers of the resistance to race 15B conditioned by Sr7, with Sr9 probably having the greatest effect.


1977 ◽  
Vol 57 (3) ◽  
pp. 633-641 ◽  
Author(s):  
D. R. KNOTT ◽  
J. P. SRIVASTAVA

Eight cultivars of common wheat showing good stem rust resistance in International Spring Wheat Rust Nurseries were selected. They were backcrossed to the susceptible cultivars Marquis and Little Club and the inheritance of their resistance to races 15B and 56 was studied. The major genes carried by the cultivars had all been identified previously. The cultivars and the major genes carried by them were as follows: Andes Sib (Sr8, Sr9?), Colotana (Sr8), Giza-Hegazy (Sr7a, Sr9a or b) Huascav (Sr9d), S.A. 112/52 (Sr9d), Bonza Selection (Sr6), Kuntur (Sr6, Sr7a) and Maribal Marina (Sr7a). In addition, four of the cultivars carried one or more genes giving very moderate resistance to one or both of the races.


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.


2010 ◽  
Vol 61 (12) ◽  
pp. 1036 ◽  
Author(s):  
J. Zhang ◽  
C. R. Wellings ◽  
R. A. McIntosh ◽  
R. F. Park

Seedling resistances to stem rust, leaf rust and stripe rust were evaluated in the 37th International Triticale Screening Nursery, distributed by the International Wheat and Maize Improvement Centre (CIMMYT) in 2005. In stem rust tests, 12 and 69 of a total of 81 entries were postulated to carry Sr27 and SrSatu, respectively. When compared with previous studies of CIMMYT triticale nurseries distributed from 1980 to 1986 and 1991 to 1993, the results suggest a lack of expansion in the diversity of stem rust resistance. A total of 62 of 64 entries were resistant to five leaf rust pathotypes. In stripe rust tests, ~93% of the lines were postulated to carry Yr9 alone or in combination with other genes. The absence of Lr26 in these entries indicated that Yr9 and Lr26 are not genetically associated in triticale. A high proportion of nursery entries (63%) were postulated to carry an uncharacterised gene, YrJackie. The 13 lines resistant to stripe rust and the 62 entries resistant to leaf rust represent potentially useful sources of seedling resistance in developing new triticale cultivars. Field rust tests are needed to verify if seedling susceptible entries also carry adult plant resistance.


1961 ◽  
Vol 41 (1) ◽  
pp. 109-123 ◽  
Author(s):  
D. R. Knott

The rust resistance of a 56-chromosome wheat-Agropyron derivative was found to be controlled by a gene or genes on a single Agropyron chromosome. Resistant wheat plants having 21II of wheat chromosomes plus a single added Agropyron chromosome were produced. Spikes of these plants were irradiated with either gamma rays or X-rays and seeds were irradiated with thermal neutrons. As a result of the irradiation, in at least five lines and possibly seven a piece of the Agropyron chromosome carrying the gene or genes for rust resistance was transferred to a wheat chromosome. One of the translocations is transmitted normally through the gametes but the remaining six show irregularities in transmission particularly through the pollen.


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


1971 ◽  
Vol 13 (2) ◽  
pp. 186-188 ◽  
Author(s):  
D. R. Knott

Tests were carried out to identify and locate the genes for resistance to races 15B-1L and 56 in Hope and H-44. The gene Sr1 which conditions resistance to race 56 was found to be either very closely linked or more probably allelic to Sr9. It is proposed that it be redesignated Sr9d. The gene Sr2 which conditions adult plant resistance to race 56 appears to be on chromosome 3B. The recessive gene conditioning resistance to race 15B-1L was identified as sr17 which is on chromosome 7B.


1961 ◽  
Vol 41 (3) ◽  
pp. 587-601 ◽  
Author(s):  
D. R. Knott ◽  
I-Sun Shen

In an attempt to locate new genes for stem rust resistance, 11 varieties of wheat of as diverse origins as possible were studied. Each variety was backcrossed to the susceptible parent Marquis. The F2 families from the backcrosses were tested with races 15B and 56, and the inheritance of resistance determined. The genes carried by each variety were identified from the results of test crosses with varieties carrying known genes and with lines of Marquis carrying single genes for resistance. Most of the resistance present in the 11 varieties could be accounted for on the basis of known genes (Sr6 – Sr10). However, at least one new gene conditioning moderate resistance to race 15B, and possibly one or more new genes conditioning moderate resistance to race 56, were identified.


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