INHERITANCE OF LOOSE SMUT RESISTANCE: II. INHERITANCE OF RESISTANCE IN THREE BARLEY VARIETIES TO RACES 1, 2, AND 3 OF USTILAGO NUDA (JENS.) ROSTR.

1963 ◽  
Vol 43 (3) ◽  
pp. 390-396 ◽  
Author(s):  
D. R. Metcalfe ◽  
W. H. Johnston

The inheritance of resistance of the barley varieties Br. 5479–754, a derivative of Jet (C.I. 967), PR28, a derivative of C.I. 4966, and Valkie (C.I. 5748) to races 1, 2 and 3 of Ustilago nuda (Jens.) Rostr. was studied. The genes for resistance in all varieties were dominant in effect. Resistance to races 2 and 3 in Br. 5479–754 was due to a single gene and resistance to race 1 to duplicate genes. A single gene in PR28 controlled resistance to all three races. Valkie proved susceptible to race 2 and had single and independent genes for resistance to each of races 1 and 3. The genes for resistance to the various smut races in each variety was independent of those in the other two.The winter barley variety C.I. 4966 is a valuable new source of immunity to U. nuda.

1962 ◽  
Vol 42 (1) ◽  
pp. 69-77 ◽  
Author(s):  
E. N. Larter ◽  
H. Enns

Four barley varieties, each immune to a Valki-attacking culture of loose smut (designated as race 2), were studied with respect to the inheritance of their resistance. Jet (C.I. 967) and Nigrinudum (C.I. 2222) were each found to possess two independent dominant genes determining resistance. Steudelli (C.I. 2266) proved to be immune to race 2 through the action of a single dominant gene, while resistance of Hillsa (C.I. 1604) was found to be conditioned by two complementary dominant genes. The absence of susceptible F3 families in crosses between Jet, Nigrinudum, and Steudelli indicated that these three varieties have in common a gene or genes for resistance to the race of smut used. The two complementary genes for resistance in Hillsa proved to be distinct from those of the other three varieties under study.The use of genetic analyses of disease resistance based upon classification of F3 families of the backcross to the resistant source is described and the merits of such a method are discussed.


1969 ◽  
Vol 49 (4) ◽  
pp. 447-451 ◽  
Author(s):  
J. G. Moseman ◽  
D. R. Metcalfe

The reactions of 18 cultivars and selections of barley, Hordeum vulgare L., to inoculations with three cultures of the loose smut fungus, Ustilago nuda (Jens.) Rostr., were determined. The following conclusions were derived by analyzing the reactions of cultivars Jet (CI 967) and Milton (CI 4966) and derivatives from them to inoculations with cultures 244 of race 2, 49-70 of race 2, and 10 of race 1. Jet was shown to have two genes, Un3 and Un6, and Milton, one gene, Un8. Derivatives from Jet with only gene Un6 were distinguished from those with genes Un3 and Un6. Five host selections known to have a gene or genes at the same locus as Jet were shown to have gene Un6 or a similar gene at that locus.


1962 ◽  
Vol 42 (1) ◽  
pp. 176-189 ◽  
Author(s):  
D. R. Metcalfe

The inheritance of reaction to single cultures of Ustilago nuda (Jens.) Rostr., Ustilago nigra Tapke, and Ustilago hordei (Pers.) Lagerh. was studied in the F1, F2 and F3 generations of crosses between the resistant barley variety Jet and the susceptible varieties Vantage and Plush. It was concluded that Jet has a single dominant gene for resistance of U. nuda and probably dominant genes for resistance of U. nigra and U. hordei. A close association was detected, in the segregating populations, between the reactions to U. nigra and U. hordei. No association was detected between resistance to U. nuda and resistance to the other two smut species. No associations were found between reaction to any of the three smut species and the genes responsible for the following marker characters: resistance vs. susceptibility to Puccinia graminis tritici Eriks. and Henn. (Tt), two- vs. six-row spike (Vv), naked vs. hulled kernel (Nn), black vs. white lemma and pericarp (Bb), and rough vs. smooth awn (Rr).


Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 25-32
Author(s):  
P.S. Shindrova

SUMMARY Downy mildew caused by the fungus Plasmopara halstedii is the main disease on sunflower in Bulgaria. In recent years a number of authors have reported the occurrence of new more virulent races of the pathogen. According to other authors these races demonstrate resistance to the fungicides used up to now. This fact is rather alarming and imposes the necessity of annual researches with the aim of following the changes in the downy mildew race variability. In the period 1995-1997 downy mildew isolates were collected from the following locations: Bourgas, Boyanovo, Karnobat, Ognyanovo, Selanovtsi, Kroushari, Lovech, Koubrat, Brashlyan, Sitovo, Tervel, Targovishte, IWS “Dobroudja” and Dobrich. The samples were assessed for virulence on a set of sunflower differential - lines under greenhouse conditions. The obtained results do not reveal a great race variability of downy mildew population in Bulgaria. In the period of study two races of the pathogen were identified: race 1 which infects the differential lines without genes for resistance to the pathogen. It is distributed in all sunflower production areas of the country. The other one is race 2. It is of limited distribution and has been registered in individual fields of north-east and north-west Bulgaria. It attacks the differential lines carrying the resistance gene Pl-1.


1982 ◽  
Vol 33 (5) ◽  
pp. 763 ◽  
Author(s):  
JL Rose ◽  
JAG Irwin ◽  
MJ Ryley ◽  
PW Langdon ◽  
LB Jenner

Phytophthora megasperma f.sp, glycinea, the cause of phytophthora root and stem rot of soybeans, was found to be widespread in southern Queensland. Race determinations on 56 isolates were made at 26�C using the North American differential set. Thirty isolates resembled race 1 (virulent only on Harosoy), while the remaining isolates killed varying proportions of the other six differentials. Two of these isolates most closely resembled race 15. When race determinations were repeated for four isolates at 31�C, each isolate was more virulent on most of the differentials. One isolate resembling race 1 at 26�C would have been classified as race 2 at 31�C. All of the cultivars grown in Queensland were susceptible to hypocotyl inoculation, indicating the absence of genes conditioning resistance to races 1 and 15. Small proportions of plants in some cultivars, including Davis and Bragg were resistant to hypocotyl inoculation. The field resistances of 21 cultivars and breeding lines were assessed in a disease nursery. Progressive assessments of disease incidence were significantly correlated with grain yield and plant height. Davis had the highest level of field resistance while Ross and Semstar had the lowest. A breeding line (HS 1115) was identified as highly resistant to the fungus, both in the field and following hypocotyl inoculation. Three F6 lines from the cross Davis x Bragg showed a range of disease reactions, with the best showing an equivalent level of resistance to that of Davis.


2006 ◽  
Vol 96 (12) ◽  
pp. 1355-1362 ◽  
Author(s):  
Jessica S. Engle ◽  
Laurence V. Madden ◽  
Patrick E. Lipps

To determine the distribution of Stagonospora nodorum and Pyrenophora tritici-repentis on wheat in Ohio, flag leaves with lesions were collected from wheat-producing counties in 2002 and 2003. Counties were arbitrarily grouped into seven regions. Log-linear analysis of pathogen presence within regions indicated that the presence of S. nodorum was independent of the presence of P. tritici-repentis. A logistic analysis revealed that the occurrence of both pathogens varied by region in one or both years. The aggressiveness of S. nodorum isolates was determined by inoculating two susceptible genotypes with a subsample of isolates from each region from both years. S. nodorum isolates obtained from northeast Ohio, with fewer wheat fields, were less aggressive than those from other regions. Isolates obtained from west-central Ohio, surrounded by regions with high wheat production annually, were significantly more aggressive than those obtained in the remaining five regions. Isolates from the five other regions did not differ significantly (P > 0.05) in aggressiveness. Races 1 and 2, and a few race 3 isolates, of P. tritici-repentis were detected in Ohio. The distribution of P. tritici-repentis races 1 and 2 was not associated with any region, although the prevalence of race 1 was three times greater than race 2. The rarer race 3 was associated with three dispersed regions. Results indicate that S. nodorum was the major wheat leaf-blotching pathogen. There were no positive or negative associations of S. nodorum and P. tritici-repentis or individual races of P. tritici-repentis in any of the tested regions, which indicates that neither pathogen can be used to predict the presence of the other. The isolated northeastern corner of Ohio appeared to contain isolates of S. nodorum with unique characteristics and potentially only one race of P. tritici-repentis, indicating that this area may be genetically isolated from the remaining tested areas of the state.


1989 ◽  
Vol 37 (6) ◽  
pp. 511 ◽  
Author(s):  
KS Bateman ◽  
JM Hinch ◽  
JE Ralton ◽  
AE Clarke ◽  
JA Mckenzie ◽  
...  

The inheritance of resistance of cowpea to Phytophthora vignae race 2 has been examined in seedlings from F1, F2 and backcross generations from crosses between a susceptible cultivar, cv. Poona, and a near-isogenic resistant cultivar, cv. Caloona. Resistance is dominant and controlled by a single gene (gene complex). A non-subjective method, based on comparison of the lengths of lesions produced on hybrid and parental seedlings after inoculation of cut epicotyls, was used to classify hybrid plants as resistant and susceptible. This method takes into account the variation in responses to infection between batches of plants assayed on different days. Two other criteria were used to indicate resistance: the presence of reddening responses, 3 days post-inoculation; and the ability of plants to recover 35 days after inoculation of cut epicotyls. Resistance is also expressed in excised leaves of rooted cuttings, and in stem callus derived from cv. Caloona and F1 plants.


2003 ◽  
Vol 93 (2) ◽  
pp. 147-152 ◽  
Author(s):  
K. S. Lee ◽  
S. Rasabandith ◽  
E. R. Angeles ◽  
G. S. Khush

Genetic analysis for resistance to bacterial blight (Xanthomonas oryzae pv. oryzae) of 21 rice (Oryza sativa L.) cultivars was carried out. These cultivars were divided into two groups based on their reactions to Philippine races of bacterial blight. Cultivars of group 1 were resistant to race 1 and those of group 2 were susceptible to race 1 but resistant to race 2. All the cultivars were crossed with TN1, which is susceptible to all the Philippine races of X. oryzae pv. oryzae. F1 and F2 populations of hybrids of group 1 cultivars were evaluated using race 1 and F1 and F2 populations of hybrids of group 2 cultivars were evaluated using race 2. All the cultivars showed monogenic inheritance of resistance. Allelic relationships of the genes were investigated by crossing these cultivars with different testers having single genes for resistance. Three cultivars have Xa4, another three have xa5, one has xa8, two have Xa3, eight have Xa10, and one has Xa4 as well as Xa10. Three cultivars have new, as yet undescribed, genes. Nep Bha Bong To has a new recessive gene for moderate resistance to races 1, 2, and 3 and resistance to race 5. This gene is designated xa26(t). Arai Raj has a dominant gene for resistance to race 2 which segregates independently of Xa10. This gene is designated as Xa27(t). Lota Sail has a recessive gene for resistance to race 2 which segregates independently of Xa10. This gene is designated as xa28(t).


1962 ◽  
Vol 42 (3) ◽  
pp. 472-480 ◽  
Author(s):  
D. R. Metcalfe ◽  
S. B. Helgason

The immune reaction of the barley varieties Bifarb (C.I. 3951-3), Kitchin (C.I. 1296-1), Nigrinudum (C.I. 2222), Jet (C.I. 967), and C.I. 5798 to a Trebi-attacking culture of Ustilago nuda (Jens.) Rostr. was studied in the F2 and F3 generations of crosses between these varieties and the U. nuda susceptible variety Newal (C.I. 6088). Resistance was found to be conditioned by single dominant genes. Studies of the F3 and F4 generations of crosses among the immune varieties indicated that the genes for immunity were each located at the same locus. A study of the F3 generation of a cross between Jet and the third outer-glume mutant from Valkie (C.I. 5748), designated herein as Valkie-trd, indicated that these genes for immunity differed from that in Valkie. Because of the similarity of the genetics of reaction to U. nuda in the five varieties, it was concluded that they probably originated from a common Abyssinian ancestor.


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