Variability of uredial cultures of Puccinia graminis tritici derived from 'vegetative' axenic mycelium

1978 ◽  
Vol 56 (7) ◽  
pp. 855-861 ◽  
Author(s):  
G. J. Green ◽  
P. G. Williams ◽  
D. J. Maclean
Keyword(s):  
Growth Rate ◽  
Mitotic Division ◽  
Reduction Division ◽  
Puccinia Graminis ◽  
Diploid Nucleus ◽  
Two Cultures ◽  
Puccinia Graminis Tritici ◽  
Parent Culture ◽  
Axenic Cultures ◽  
Implant Technique

Two of 26 'vegetative' axenic cultures of Puccinia graminis tritici were induced to infect wheat by the epidermal stripping and mycelial implant technique. Only one of these two cultures produced urediospores and could be propagated on wheat. The urediospores obtained from implants had poor infectivity and there was a long incubation period. Single pustule isolates varied in growth rate, colour, virulence, sporulation, pustule type, and number of nuclei per spore. The uredial cultures comprised two groups: (1) one group with dikaryotic spores which resembled the parent culture race 126-Anz-6,7, Sydney University No. 334; (2) another group with monokaryotic spores which varied widely. The variability of the uredial cultures is interpreted as evidence that the diploid nucleus of the 'vegetative' axenic cultures originated by fusion of two haploid nuclei and divided in two ways: firstly, by a reduction division that produced two haploid nuclei and reconstituted a dikaryon similar to race 126-Anz-6,7, and secondly, by a mitotic division that produced diploids, variant aneuploids, and possibly mitotic recombinants.

COMPARATIVE STUDIES OF NORTH AMERICAN AND EUROPEAN CULTURES OF THE ROOT ROT FUNGUS, FOMES ANNOSUS (FR.) COOKE

1955 ◽  
Vol 33 (5) ◽  
pp. 416-428 ◽  
Author(s):  
D. E. Etheridge
Keyword(s):  
Growth Rate ◽  
North American ◽  
Growth Rates ◽  
Root Rot ◽  
Linear Growth ◽  
Morphological Characteristics ◽  
Dry Weight ◽  
Cellulolytic Activity ◽  
Ph Optimum ◽  
Two Cultures

Cultures of Fames annosus originating in Europe could not be distinguished from those originating in North America either by colony appearance, growth rate, pH optimum, or cellulolytic activity. Three growth rate types on 2.5% malt agar were recognized and these are ascribed to individual variation rather than to host or geographical influences. Successive subculturing produced variants that fell into three growth classes. Half of the isolates displayed spontaneous, but reversible, changes in growth rate and colony appearance during subculturing and this is discussed from the standpoint of genetical and environmental influences. Cultures displaying different morphological characteristics and linear-growth rates differed little metabolically; each had a similar pH optimum ranging from 4.6 to 5.5, and each proved capable of altering the initial acidity of the medium to a reaction which was more suitable for growth. Two cultures were characterized by double pH optima at 4.6 and 5.5. Cultures having different linear-growth rates produced about the same dry-weight of mycelium on a cellulose substrate in a semisynthetic nutrient solution. On the basis of a statistical analysis of cellulose utilization by representative isolates it was impossible to distinguish between North American and European cultures.

Epidemiology of Puccinia graminis f.sp. tritici-Ug99 in the Rift Valley “Flyway” from Uganda-Kenya to Yemen

2012 ◽  
Vol 13 (1) ◽  
pp. 31 ◽  
Author(s):  
Subrahmaniam Nagarajan ◽  
Hans J. Kogel ◽  
Jan C. Zadoks
Keyword(s):  
Rift Valley ◽  
Puccinia Graminis ◽  
Puccinia Graminis Tritici ◽  
Wheat Cultivation

Dispersal of a new virulence of Puccinia graminis tritici (Pgt)-Ug99 from Uganda-Kenya to Yemen, over >1000 km, happened in four years. Geo-agro-ecology of wheat cultivation and the epidemiology of Pgt indicate that the Rift Valley is a natural conduit “flyway.” The widely prevalent “green bridges” favor survival and spread of Pgt. This part of the Rift Valley is one single epidemiological zone, and the annual Pgt build-up is from the endogenous inoculum. Accepted for publication 18 October 2012. Published 14 November 2012.

scholarly journals A Third Factor for Resistance to Puccinia graminis Tritici

Nature ◽  
1945 ◽  
Vol 155 (3929) ◽  
pp. 205-205
Author(s):  
I. A. WATSON ◽  
W. L. WATERHOUSE
Keyword(s):  
Puccinia Graminis ◽  
Puccinia Graminis Tritici

STUDIES ON THE NATURE OF RUST RESISTANCE IN WHEAT: VI. EFFECT OF HYDROGEN ION CONCENTRATION, PHENOLIC COMPOUNDS, AND HOST EXTRACTS ON THE GERMINATION OF UREDINIOSPORES OF PUCCINIA GRAMINIS TRITICI, FORM 21

1934 ◽  
Vol 11 (6) ◽  
pp. 667-686 ◽  
Author(s):  
J. Ansel Anderson
Keyword(s):  
Phenolic Compounds ◽  
Rust Resistance ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Puccinia Graminis ◽  
Inhibitory Effects ◽  
Hydrogen Ion Concentration ◽  
Puccinia Graminis Tritici ◽  
The Press ◽  
Germ Tubes

Urediniospores of Puccinia graminis tritici, form 21, were sown on buffer solutions covering the range from pH 3 to pH 8. Maximum germination was obtained between pH 5.8 and 6.5, with indications that if the point of maximum germination could be determined with precision it would be found to lie in the neighborhood of pH 6.2.The effect of buffered and unbuffered solutions of pure phenolic compounds on the germination of urediniospores was studied. Greater inhibition was obtained with unbuffered solutions owing to the additional effect of hydrogen ion concentration. In buffered solutions, at pH 6.0, germination was prevented by 45 p.p.m. of hydroquinone, 125 of o-cresol, 180 of anisic acid, 250 of benzoic acid, 340 of catechol, 400 of guaiacol and 600 of phenol. A number of other compounds were also studied. The inhibitory effects of compounds, of which the bactericidal effects are known, are fairly closely related to their bactericidal efficiency.Investigations were made of the inhibitory effects on spore germination and the growth of germ tubes, of aqueous dilutions of 15, 10, 5 and 2.5% of the press-juice of Vernal, Khapli, Marquis and Little Club wheats. Statistical treatment of the data accumulated in ten series of determinations, in which a total of 160,000 spores was counted, showed that significant differences occurred between varieties and that variations in the total solid content and hydrogen ion concentration of the press-juice had no consistent effect upon the results. Although the results were not entirely clear-cut, it is concluded that the varieties fall in the following order with respect to increasing inhibitory effect of their extracts: Vernal, Marquis, Khapli and Little Club. Since Vernal and Khapli are resistant to form 21 whereas Marquis and Little Club are susceptible, the results fail to show any relationship between the effects of host extracts on the germination of urediniospores, or on the growth of germ tubes, and the rust resistance of the variety.

Haustoria-like branches in axenic cultures of Puccinia graminis f. sp. tritici

1969 ◽  
Vol 47 (11) ◽  
pp. 1816-1817 ◽  
Author(s):  
P. G. Williams
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Artificial Culture ◽  
Axenic Cultures

Hyphae of the wheat stem rust fungus form short, lateral projections under conditions of artificial culture that are unfavorable for saprophytic growth. It is suggested that the structures are homologous with the haustoria of intercellular rust mycelium.

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