INHERITANCE OF PATHOGENICITY AND UREDIOSPORE COLOR IN CROSSES BETWEEN PHYSIOLOGIC RACES OF OAT STEM RUST

In the F1 generation of crosses between physiologic races 7 (orange) and 11 (red) of Puccinia graminis Pers. var. Avenae Erikss. and Henn., the medium sized uredia (type 2 infection) formed by race 11 on the oat variety White Tartar were dominant to the large (type 4) uredia of race 7, and the small (type 1) uredia of race 7 on the variety Richland were dominant to the type 4 uredia formed by race 11. On the varieties Sevnothree and Joanette Strain, the F1 hybrids produced the same type of infection as did the "maternal" parent race, that is, hybrids from race 7 × race 11 crosses produced a type 4 infection like race 7, and reciprocal hybrids produced a type 1 infection like race 11. These facts led to the suggestion that the cytoplasm of the maternal parent race influenced the infection type of the F1 hybrid on these two oat varieties.A study of the F2 generation of the cross race 11 × race 7 showed that on the varieties White Tartar and Richland the dominant and recessive infection types appeared in a ratio of 9:7, which suggests that their inheritance is governed by two pairs of complementary genes. The distribution of physiologic races in F2 conforms to this assumption and indicates that the genes governing infection types on these two varieties associate at random to produce physiologic races 1, 11, 3, and 4. These races occurred in F2 in a ratio of 31: 20: 22: 12, as compared to an expected ratio of 27: 21: 21: 16. On the variety Sevnothree, 84 of 85 F2 cultures produced type 1 uredia, in this way resembling the maternal parent, race 1, and the maternal grandparent, race 11. One F2 culture, only produced the type 4 uredia characteristic of the paternal grandparent, race 7. It is concluded from this study, and from crosses between races 1 and 2, that the maternal (cytoplasmic) influence evidenced in the F1 generation persists m F2 and F3.In F1, the red urediospore color of race 11 was dominant to the orange color of race 7. The distribution in these two color classes in F2 and F3 suggests that the inheritance of urediospore color is governed by a single pair of genes.

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Vegetative Compatibility Groups of Fusarium oxysporum f. sp. lactucae from Lettuce

Plant Disease ◽

10.1094/pd-89-0237 ◽

2005 ◽

Vol 89 (3) ◽

pp. 237-240 ◽

Cited By ~ 23

Author(s):

Matias Pasquali ◽

Flavia Dematheis ◽

Giovanna Gilardi ◽

Maria Lodovica Gullino ◽

Angelo Garibaldi

Keyword(s):

Fusarium Oxysporum ◽

Genetic Relatedness ◽

The United States ◽

Vegetative Compatibility ◽

Vegetative Compatibility Group ◽

Vegetative Compatibility Groups ◽

Compatibility Group ◽

Race 1

Fusarium oxysporum f. sp. lactucae, the causal agent of Fusarium wilt of lettuce, has been reported in three continents in the last 10 years. Forty-seven isolates obtained from infected plants and seed in Italy, the United States, Japan, and Taiwan were evaluated for pathogenicity and vegetative compatibility. Chlorate-resistant, nitrate-nonutilizing mutants were used to determine genetic relatedness among isolates from different locations. Using the vegetative compatibility group (VCG) approach, all Italian and American isolates, type 2 Taiwanese isolates, and a Japanese race 1 were assigned to the major VCG 0300. Taiwanese isolates type 1 were assigned to VCG 0301. The hypothesis that propagules of Fusarium oxysporum f. sp. lactucae that caused epidemics on lettuce in 2001-02 in Italian fields might have spread via import and use of contaminated seeds is discussed.

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First Report of Virulence in Argentine Populations of Puccinia sorghi to Rp Resistance Genes in Corn

Plant Disease ◽

10.1094/pdis.2000.84.8.921a ◽

2000 ◽

Vol 84 (8) ◽

pp. 921-921 ◽

Cited By ~ 3

Author(s):

M. Gonzalez

Keyword(s):

Specific Resistance ◽

Infection Type ◽

Wide Spectrum ◽

Leaf Tissue ◽

The United States ◽

Santa Fe ◽

Puccinia Sorghi ◽

Rust Severity ◽

Infection Types

Common rust (Puccinia sorghi) is a chronic disease of corn (Zea mays L.) in Argentina. Factors contributing to the disease include relatively susceptible germ plasm, planting late in the season, and variability within populations of P. sorghi. Several genes for race-specific resistance to common rust (i.e., Rp genes) were identified based on virulence in populations of P. sorghi in the United States (1). The objective of this research was to examine the virulence of Argentine populations of P. sorghi against 24 alleles at four Rp loci that condition race-specific resistance to common rust. Rp genes in an R168-inbred background were planted in trials at two locations in the central corn belt of Argentina. In the 1996-97, 1997-98, and 1999-2000 seasons, trials were planted in Pergamino (Province of Buenos Aires). In the 1998-99 season, the trial was planted in Zavalla (Province of Santa Fe). Plants were exposed to naturally occurring local populations of P. sorghi. About 3 to 4 weeks after anthesis, rust severity (percentage of leaf tissue with uredinia) and infection type were rated for all plants. Four categories of infection type were: 1—no rust, necrotic or chlorotic flecks, 2—small uredinia with or without necrotic flecks, 3—large uredinia, and 4—large uredinia with banding. Three lines with Rp genes (Rp1-N, Rp3-A, and Rp3-C) had infection type 1 with necrotic flecks and severity of 0%. Lines with other Rp genes (Rp1-A, Rp1-B, Rp1-C, Rp1-D, Rp1-E, Rp1-F, Rp1-G, Rp1-H, Rp1-I, Rp1-J, Rp1-K, Rp1-M, Rp1-N, Rp3-A, Rp3-B, Rp3-C, Rp3-D, Rp3-E, Rp4-A, Rp4-B, and Rp5) had infection types 2 to 4 and severity ranged from 5 to 35%. Severity was affected by the virulence of the populations and the environmental conditions in each trial. These results are evidence of a wide spectrum of virulence in P. sorghi populations in Argentina. Reference: (1) W. Hagan and A. Hooker. Phytopathology 55:193, 1965.

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Survey of Fusarium spp. Associated with Fruit Rot of Pumpkin in Ohio

Plant Health Progress ◽

10.1094/php-2010-0827-01-rs ◽

2010 ◽

Vol 11 (1) ◽

pp. 9

Author(s):

Christian A. Wyenandt ◽

Richard M. Riedel ◽

Landon H. Rhodes ◽

Mark A. Bennett ◽

Steven G. P. Nameth

Keyword(s):

Cucurbita Pepo ◽

Fusarium Species ◽

Fruit Rot ◽

Fusarium Spp ◽

Surface Type ◽

Race 1 ◽

Type 3 ◽

Magic Lantern

From 2000 to 2002 commercial pumpkin (Cucurbita pepo) fields in Ohio were surveyed for Fusarium fruit rot. From six counties in 2000, 2001, and 2002, a total of 43 isolates from eight farms, 84 isolates from nine farms, and 40 isolates from six farms were collected, respectively. Fusarium solani f. sp. cucurbitae race 1 was the most commonly isolated Fusarium species from infected pumpkin fruit in Ohio. Other Fusaria isolated from infected fruit included F. oxysporum, F. graminearum, and F. acuminatum. A survey of infected pumpkin fruit in the field and inoculation studies of mature, healthy pumpkin cultivar Magic Lantern in the laboratory resulted in three types of fruit rot symptoms. Type 1, caused by F. oxysporum and F. acuminatum, resulted in a slow-expanding rot just below the rind surface of the infected fruit. Type 2, caused by F. graminearum, resulted in an expanding, slightly sunken, irregular rot of the rind surface. Type 3, caused by F. solani resulted in expanding, circular sunken lesions on the fruit surface bearing white to tan sporodochia. This is the first report of F. solani f. sp. cucurbitae race 1, F. oxysporum, F. acuminatum, and F. graminearum causing fruit rot of pumpkin in Ohio. Accepted for publication 26 July 2010. Published 27 August 2010.

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A single-spore analysis of rust pustules produced by mixing isolates of two races of Puccinia coronata var. avenue

Canadian Journal of Botany ◽

10.1139/b68-197 ◽

1968 ◽

Vol 46 (11) ◽

pp. 1455-1458

Author(s):

A. Dinoor ◽

J. Khair ◽

G. Fleischmann

Keyword(s):

Infection Type ◽

The Other ◽

Puccinia Coronata ◽

Masking Effect ◽

Single Spore ◽

New Race ◽

Infection Types ◽

Differential Varieties ◽

Parent Race

Urediospores of pairs of isolates of Puccinia coronata var. avenae were simultaneously inoculated side by side on a susceptible oat leaf to produce a common pustule. The infection types of the culture from the single pustule, and from single-spore isolates of the pustule, were determined on key differential varieties distinguishing the component biotypes. The composition of the pustule was found to vary with the component races involved, and among pustules established from the same components.One pair of component races produced pustules which were phenotypically like one or the other of the isolates used in the mixture. Single-spore isolates from these pustules gave the same infection type as the pustule from which they were isolated, indicating that either one isolate alone produced the pustule, or that it predominated in what would then be a compound pustule.Another pair produced infection types unlike those of either parent race, and thus behaved phenotypically as a new race on the differential varieties. However, single-spore isolates from such pustules behaved as one or the other of the components. The masking effect of virulence over avirulence was also demonstrated by single-spore analysis of these compound pustules.

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MENDELIAN INHERITANCE OF CERTAIN PATHOGENIC CHARACTERS OF PUCCINIA GRAMINIS TRITICI

Canadian Journal of Research ◽

10.1139/cjr40c-056 ◽

1940 ◽

Vol 18c (12) ◽

pp. 599-611 ◽

Cited By ~ 19

Author(s):

Thorvaldur Johnson ◽

Margaret Newton

Keyword(s):

Higher Plants ◽

Mendelian Inheritance ◽

Puccinia Graminis ◽

Single Factor ◽

Factor Pair ◽

Maternal Parent ◽

Puccinia Graminis Tritici ◽

Independent Segregation ◽

Physiologic Races ◽

Infection Types

Crossing and selfing studies with physiologic races of Puccinia graminis Tritici have shown that certain pathogenic characters are dominant to others. The "0" type of infection (absence of rust pustules) on the variety Kanred was found to be dominant to the "4" type (large rust pustules), so that when a race producing the "0" type was crossed with a race producing the "4" type the hybrid rust produced the "0" type. When the hybrid race was selfed, the "0" type occurred about three times as frequently in F2 as the "4" type, a fact indicating that rust behaviour on this variety is governed by a single-factor pair. The "4" type of infection on the variety Mindum normally was dominant to the "1" type (very small pustules) and occurred about three times as frequently in F2. The "1" type of infection on the emmer variety Vernal was dominant to the "4" type and recurred in some crosses, about 15 times as frequently in F2 as the "4" type. Rust behaviour on this variety appears to be governed by duplicate factors, each factor being capable of exerting the same effect. Evidence derived from a study of the F2 populations of two crosses between races 9 and 36 indicated that the factors governing rust behaviour on Kanred, Mindum, and Vernal, were different and were inherited independently of each other. In crosses in which the two parent races produced different infection types on the variety Marquis, the cytoplasm of the maternal parent race appeared to influence pathogenicity on this variety.As a result of these studies it is concluded that despite the binucleate condition of stem rust in its uredial phase, the genes function as if they were present in a single diploid nucleus, and that, owing to fusion of the nuclei in the teliospore and subsequent meiotic divisions, independent segregation of factors occurs as in higher plants. The crossing of physiologic races and the selling of the hybrids lead to various recombinations of existing pathogenic characters that may result in the formation of new physiologic races without involving the creation of pathogenic characters not possessed by the parent races.

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