Lack of genetic variability in French identified races of Plasmopara halstedii, the cause of downy mildew in sunflower Helianthus annuus

1997 ◽  
Vol 43 (3) ◽  
pp. 260-263 ◽  
Author(s):  
Patricia Roeckel-Drevet ◽  
Véronique Coelho ◽  
Paul Nicolas ◽  
Jeanne Tourvieille ◽  
Denis Tourvieille de Labrouhe

Downy mildew of sunflower (Helianthus annuus L.) incitated by Plasmopara halstedii is a potentially devastating disease. We report here the finding of two new races of P. halstedii and also two Apron35S fungicide-resistant isolates of race A. Using the random amplified polymorphic DNA (RAPD) technique as an initial screening for genetic variation within P. halstedii French races, genetic variation was not found between isolates within races 1, A, or B, and very few polymorphisms were distinguished between all French races known today.Key words: Plasmopara halstedii, race, genetic variability, RAPD.

Euphytica ◽  
1996 ◽  
Vol 91 (2) ◽  
pp. 225-228 ◽  
Author(s):  
Patricia Roeckel-Drevet ◽  
Geneviève Gagne ◽  
Said Mouzeyar ◽  
Laurent Gentzbittel ◽  
Jacqueline Philippon ◽  
...  

1999 ◽  
Vol 45 (9) ◽  
pp. 797-803 ◽  
Author(s):  
Patricia Roeckel-Drevet ◽  
Jeanne Tourvieille ◽  
Joël R Drevet ◽  
Véronique Says-Lesage ◽  
Paul Nicolas ◽  
...  

The obligate parasitic fungus-like organism Plasmopara halstedii (Farl.) Berl. et De Toni, is the causal agent of downy mildew disease in sunflower (Helianthus annuus). New races of this economically important parasite are regularly detected throughout the world. In addition, fungicide-resistant isolates have been reported in Europe and North America. These observations of parasite evolution, as well as the risk of propagation of the disease by infected seeds, means that it is necessary to guarantee the absence of Plasmopara halstedii in seed shipments. We report here the development of a rapid assay that can be used to detect infection by Plasmopara halstedii in plant tissues. Based on the nucleotide sequence information obtained from one cloned random amplified polymorphic DNA fragment, specific oligonucleotides were designed and used as primers for in vitro DNA amplification by polymerase chain reaction. An amplification product was detected on agarose gel stained with ethidium bromide when DNA from various Plasmopara halstedii races was tested, whereas no amplified DNA was detected when DNA from other origins was tested, including DNA from the host plant. The sensitivity of the technique was evaluated. The assay successfully reveals the presence of Plasmopara halstedii in infected sunflower plants prior to sporulation.Key words : diagnosis, polymerase chain reaction, SCAR, downy mildew, Helianthus annuus.


1985 ◽  
Vol 63 (10) ◽  
pp. 1725-1729 ◽  
Author(s):  
A. Bruce Gray ◽  
W. E. Sackston

Resistance in sunflower (Helianthus annuus L.) to downy mildew (Plasmopara halstedii (Farl.) Berl. et de Toni) is conditioned by a series of Pl. genes. Races 1 (European race), 2 (Red River race), and 3 (a new North American race encountered in the Red River valley in 1980) formed similar infection structures on inoculated seedlings whether susceptible or resistant to races 1 and 2; all cultivars tested were susceptible to race 3. The zoospores encysted and produced germ tubes and appressoria on the roots and hypocotyls. Penetration occurred and mycelium and haustoria developed in both compatible and incompatible host–pathogen combinations. Resistance did not appear to involve a hypersensitive reaction occurring prior to penetration.


2001 ◽  
Vol 103 (6-7) ◽  
pp. 992-997 ◽  
Author(s):  
P. F. Bert ◽  
D. Tourvieille de Labrouhe ◽  
J. Philippon ◽  
S. Mouzeyar ◽  
I. Jouan ◽  
...  

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 1-18
Author(s):  
B.R. Prashanth Kumar ◽  
Mahesh J. Kulkarni ◽  
B.N. Veena Rao ◽  
K. Chandrika ◽  
V.R. Balakrishna Gowda ◽  
...  

SUMMARY Biochemical changes associated with downy mildew infection in sunflower revealed an increase in the total soluble proteins, 0-40% ammonium sulfate fractionated proteins and total soluble sugars. Molecular sieve chromatography of 0-40% ammonium sulphate fraction revealed for presence of a high molecular weight protein and polysaccharide in the downy mildew infected sunflower leaves. Antibodies raised against the high molecular weight protein and polysaccharide were used in the western blot/dot blot analysis. It has been shown that the downy mildew disease also induces PR proteins, which have antigenic homology with PR-S protein, a member of the PR-5 class of proteins. An increase in iPA (isopentenyl adenosine) content in the infected sample was observed. A positive correlation exists between iPA level, 0-40% protein and total sugar content. Histological studies revealed that the downy mildew fungal mycelium extensively proliferates, ramifies extensively the leaf tissue and forms a nutritional link with the host cell by producing the intracellular haustorium.


1997 ◽  
Vol 95 (4) ◽  
pp. 584-589 ◽  
Author(s):  
F. Vear ◽  
L. Gentzbittel ◽  
J. Philippon ◽  
S. Mouzeyar ◽  
E. Mestries ◽  
...  

Euphytica ◽  
2008 ◽  
Vol 164 (2) ◽  
pp. 561-570 ◽  
Author(s):  
F. Vear ◽  
F. Serre ◽  
I. Jouan-Dufournel ◽  
P. F. Bert ◽  
S. Roche ◽  
...  

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