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

1969 ◽  
Vol 47 (11) ◽  
pp. 1816-1817 ◽  
Author(s):  
P. G. Williams

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.

1986 ◽  
Vol 28 (2) ◽  
pp. 171-175 ◽  
Author(s):  
J. J. Burdon ◽  
A. P. Roelfs ◽  
A. H. D. Brown

The pattern of inheritance of isozyme alleles was examined in the F2 progeny of a sexual cross between two different physiologic races of the wheat stem rust pathogen, Puccinia graminis Pers. f. sp. tritici Eriks. &Henn. Segregation occurred at five isozyme loci (Got, Lap, Nadhd, Pgi-2 and Pgm-1). In all of these, the observed number of F2 progeny of each of the three possible isozyme phenotypes did not differ significantly from a simple 1:2:1 ratio. Joint dihybrid segregation indicated that three of the loci formed a single linkage group: Lap–Nadhd–Pgi-2.Key words: linkage, segregation.


2009 ◽  
Vol 99 (3) ◽  
pp. 282-289 ◽  
Author(s):  
S. Zhong ◽  
Y. Leng ◽  
T. L. Friesen ◽  
J. D. Faris ◽  
L. J. Szabo

Puccinia graminis f. sp. tritici is the causal agent of stem rust disease in wheat. The rust fungus has caused devastating disease epidemics throughout history and is still posing a potential threat to wheat production in some regions of the world due to the appearance of new races. To develop microsatellite or simple sequence repeat (SSR) markers for use in population genetics studies, a total of 60,579 expressed sequence tag (EST) sequences (reads) generated from P. graminis f. sp. tritici were screened for tandemly repeated di- and tri-nucleotide units using a bioinformatics approach and 708 unisequences containing putative SSR loci with six or more repeat units were identified. Flanking primers were designed for 384 unique SSR loci, which mapped to different locations of the draft genome sequence of the fungus. Of the 384 primer pairs tested, 72 EST-SSR markers were eventually developed, which showed polymorphism among 19 isolates of P. graminis f. sp. tritici and 4 isolates of P. graminis f. sp. secalis evaluated. Thirty-two of the SSR loci were also evaluated in three other rust fungi (P. triticina, P. hordei, and P. coronata f. sp. hordei) for cross-species transferability. These SSR markers derived from ESTs will be useful for characterization of population structures and for gene mapping in P. graminis.


2000 ◽  
Vol 90 (8) ◽  
pp. 819-826 ◽  
Author(s):  
P. J. Zambino ◽  
A. R. Kubelik ◽  
L. J. Szabo

Two strains of the wheat stem rust fungus, Puccinia graminis f. sp. tritici, were crossed on barberry, and a single F1 progeny strain was selfed. The parents, F1, and 81 F2 progeny were examined for virulence phenotypes on wheat differential cultivars carrying stem rust resistance (Sr) genes. For eight Sr differentials, phenotypic ratios are suggestive of single dominant avirulence genes AvrT6, AvrT8a, AvrT9a, AvrT10, AvrT21, AvrT28, AvrT30, and AvrTU. Avirulence on the Sr; (Sr ‘fleck’) differential showed phenotypic ratios of approximately 15:1, indicating epistatic interaction of two genes dominant for avirulence. Avirulence on Sr9d favored a 3:13 over a 1:3 ratio, possibly indicating two segregating genes-one dominant for avirulence and one dominant for avirulence inhibition. Linkage analysis of eight single dominant avirulence genes and 970 DNA markers identified DNA markers linked to each of these avirulence genes. The closest linkages between AvrT genes and DNA markers were between AvrT6 and the random amplified polymorphic DNA marker crl34-155 (6 centimorgans [cM]) AvrT8a and the amplified fragment length polymorphism marker eAC/mCT-197 (6 cM) and between AvrT9a and the amplified fragment length polymorphism marker eAC/mCT-184 (6 cM). AvrT10 and AvrTU are linked at distance of 9 cM.


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