A Molecular Approach to Distinguish the Bean Rust and Siratro Rust Pathogens

1991 ◽  
Vol 39 (6) ◽  
pp. 527 ◽  
Author(s):  
KS Braithwaite ◽  
JM Manners ◽  
DJ Maclean ◽  
JAG Irwin

Rust disease on the tropical pasture legume Macroptilium atropurpureum (siratro) is caused by Uromyces appendiculatus var. crassitunicatus. This pathogen was believed to be closely related to the bean (Phaseolus vulgaris) rust pathogen Uromyces appendiculatus var. appendiculatus. The genetic relationship between these two fungi was investigated. Total DNA hybridisations indicated that little homology exists between the high copy genomic DNA of these two rust fungi. Random genomic probes cloned from the bean rust fungus detected extensive Polymorphisms between the two, with only one probe from 17 being monomorphic. The ribosomal DNA repeat unit was also distinguished by RFLPs. It was calculated from the RFLP data that the bean rust fungus and the siratro rust fungus share only 8-14% sequence homology. The results indicate that the two fungi, although morphologically very similar, are not closely related genetically.

Plant Disease ◽  
1999 ◽  
Vol 83 (2) ◽  
pp. 108-113 ◽  
Author(s):  
Craig M. Sandlin ◽  
James R. Steadman ◽  
Carlos M. Araya ◽  
Dermot P. Coyne

Five isolates of the bean rust fungus Uromyces appendiculatus were shown to be specifically virulent on bean genotypes of Andean origin. This specificity was demonstrated by the virulence of five pairs of isolates on a differential set of 30 Phaseolus vulgaris landraces. Each isolate pair was from a different country in the Americas and consisted of one Andean-specific isolate and one nonspecific isolate. Of the differential P. vulgaris landraces, 15 were of Middle American origin and 15 were of Andean origin. The Andean-specific rust isolates were highly virulent on Andean landraces but not on landraces of Middle American origin. Rust isolates with virulence to Middle American landraces were also generally virulent on Andean material; no truly Middle American-specific isolates were found. Random amplified polymorphic DNA (RAPD) analysis of the rust isolates also distinguished the two groups. Four of the Andean-specific rust isolates formed a distinct group compared to four of the nonspecific isolates. Two of the isolates, one from each of the two virulence groups, had intermediate RAPD banding patterns, suggesting that plasmagomy but not karyogamy occurred between isolates of the two groups.


Heredity ◽  
1995 ◽  
Vol 75 (3) ◽  
pp. 234-242 ◽  
Author(s):  
James V Groth ◽  
John W McCain ◽  
Alan P Roelfs

1988 ◽  
Vol 1 (4) ◽  
pp. 363
Author(s):  
JAG Irwin

Morphological studies on the rust fungi of Macroptilium, Phaseolus and Vigna show that three taxa can be distinguished. The Vigna rust, Uromyces vignae, is maintained as a species distinct from the bean rust, U. appendiculatus var. appendiculatus. A new variety, Uromyces appendiculatus (Pers.) Unger var. crassitunicatus J. Irwin, is described from Macroptilium atropurpureum. It differs from var. appendiculatus in having urediniospores with thicker side walls and more closely spaced echinulae. The teliospores are similar to those of var. appendiculatus, except that the side walls are thicker; the side walls are darker, with lineal rows of warts over the entire surface, and a conspicuous channel in the base; the hyaline apical thickening is thinner; and pedicels are more broadly attached.


1984 ◽  
Vol 62 (10) ◽  
pp. 2003-2010 ◽  
Author(s):  
R. E. Gold ◽  
K. Mendgen

The morphology of intercellular and intracellular hyphae derived from basidiospores of Uromyces appendiculatus var. appendiculatus is described. Light and electron microscopic observations of the bean rust fungus were made on susceptible leaves of Phaseolus vulgaris from 3 to 10 days after inoculation. Following egress from invaded epidermal and palisade parenchyma cells, the fungus grew rapidly and developed extensive intercellular mycelium. An amorphous to fibrillar extracellular matrix was deposited between fungal and host cell walls. Intercellular hyphae grew closely appressed to the mesophyll cells and penetrated them to form intracellular hyphae from either a terminal or nonterminal mother cell. Intracellular hyphae were fingerlike, sometimes septate, and generally remained terminal in the invaded mesophyll cell. Occasionally the fungus exited the cell to become an intercellular hypha or an intracellular hypha in an adjacent host cell. The plant rarely exhibited a resistantlike reaction at sites of penetration into mesophyll cells.


2011 ◽  
Vol 24 (7) ◽  
pp. 808-818 ◽  
Author(s):  
Sébastien Duplessis ◽  
Stéphane Hacquard ◽  
Christine Delaruelle ◽  
Emilie Tisserant ◽  
Pascal Frey ◽  
...  

Melampsora larici-populina is responsible for poplar leaf rust disease and causes severe epidemics in poplar plantations in Europe. The poplar rust genome has been recently sequenced and, in order to find the genetic determinants associated with its biotrophic lifestyle, we generated a whole-genome custom oligoarray and analyzed transcript profiles of M. larici-populina during the infection timecourse in poplar leaves. Different stages were investigated during the asexual development of the rust fungus, including resting and germinating urediniospores and seven in planta stages in the telial host. In total, 76% of the transcripts were detected during leaf infection as well as in urediniospores, whereas 20% were only detected in planta, including several transporters and many small secreted proteins (SSP). We focused our analysis on gene categories known to be related to plant colonization and biotrophic growth in rust pathogens, such as SSP, carbohydrate active enzymes (CAZymes), transporters, lipases, and proteases. Distinct sets of SSP transcripts were expressed all along the infection process, suggesting highly dynamic expression of candidate rust effectors. In contrast, transcripts encoding transporters and proteases were mostly expressed after 48 h postinoculation, when numerous haustoria are already formed in the leaf mesophyll until uredinia formation, supporting their role in nutrient acquisition during biotrophic growth. Finally, CAZymes and lipase transcripts were predominantly expressed at late stages of infection, highlighting their importance during sporulation.


2021 ◽  
Vol 7 (9) ◽  
pp. 745
Author(s):  
Kamal A. M. Abo-Elyousr ◽  
Ismail R. Abdel-Rahim ◽  
Najeeb M. Almasoudi ◽  
Sameera A. Alghamdi

This study aimed to evaluate the efficacy of endophytic bacterium to control common bean rust disease under greenhouse conditions. Endophytic bacterium Pseudomonas putida ASU15 was isolated from fresh asymptomatic common bean, identified using biochemical and molecular characteristics. In vitro, the inhibitory effect of different concentrations of P. putida (1 × 104, 1 × 105 and 1 × 106), as well as fungicide ortiva (0.01%) on uredospores germination of Uromyces appendiculatus were tested using water agar medium. The concentration showing the highest reduction of uredospores germination was at 1 × 106, while there was complete inhibition of uredospores germination associated with using ortiva. Scanning electron microscope exhibited the ability of P. putida cells to attack the cell wall of the fungal uredospores germ tubes of U. appendiculatus, causing obvious cell wall breakdown. The activities of chitinase, lipase, and protease produced by P. putida ASU15, in vitro, were evaluated spectrophotometrically. Chitinolytic, proteolytic, and lipolytic activities were exhibited, contributing 55.26, 3.87, and 26.12 U/mL, respectively. Under greenhouse conditions, treated plants with P. putida ASU15 (two days before pathogen inoculation or at the same time of pathogen inoculation) or fungicide reduced the disease severity, compared to the control. Applying P. putida ASU15 at the same time of pathogen inoculation showed reduction in disease severity (69.9%), higher than application before pathogen inoculation (54.9%). This study is considered the first report that demonstrates the mycoparasitic strategy of P. putida for controlling U. appendiculatus. In conclusion, our results revealed that P. putida ASU15 affords a significant disease reduction that may be attributed to direct suppression of pathogen spores germination.


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