Identification of rye- and wheat-types of Pseudocercosporella herpotrichoides with DNA probes

Eyespot disease caused by the soil-borne facultative fungi Oculimacula yallundae and O. acuformis is the major component of the stem-base disease complex of wheat in temperate regions of the world with a cool and wet climate. In this review, we focus on results of genetic studies concerning both partners of the host-pathogen interaction. This comprises analyses of genetic diversity of the pathogen and identification of particular genes within it, evaluation and screening methods for host resistance, resistance sources and genetics of these resistances, breeding of resistant cultivars in wheat, and application of genetic markers in tagging and tracking of eyespot resistance genes. We also attempt to foresee some of the key issues and developments that may occur in future. The identification of markers tightly linked to eyespot resistance genes is the important research focus opening the door to marker-assisted selection of resistant varieties.

Section: Molecular Genetic Studies Of the Pathogensmentioning

confidence: 99%

Advances and Prospects in Wheat Eyespot Research: Contributions from Genetics and Molecular Tools

Wei

Muranty

Zhang

2011

“…Considering a relatively large nutnber of isolates (40 W-type isolates and 51 R-type isolates) frotn diverse geographic origins throughout the world, Julian and Lticas (1990) showed that isozytne patterns tend to be homogeneous amotig isolates of the satne pathotype. Nevertheless, Priestley et al (1992) showed a greater variation in esterase patterns atnong R-type than atnong W-type isolates but, based on restriction fragtnent length polytnorphisms (RFLPs) in ribosomal or total DNA, much greater polymorphistii atnong W-type isolates was demonstrated (Nicholson et al, 1991;Thomas et al, 1992). Thus, the tnolecular cvidetice on genetic variation existing within the same pathotype appears contradictory.…”

Section: Introductionmentioning

confidence: 98%

Genetic Diversity in W‐ and R‐type Populations of Pseudocercosporella herpotrichoides Based on DNA Restriction Fragment Length Polymorphisms

Poupard

Frei

Cavelier³

et al. 1995

Thirty‐seven isolates of Pseudocercosporella herpotrichoides belonging to W‐type and 31 isolates belonging to R‐type were analysed for DNA restriction fragment length polymorphisms (RFLPs). They represent diverse geographic origins and different phenotypes related to sensitivity to fungicides. Total DNA digested with EcoRI was hybridized with 22 random DNA probes from a P. herpotrichoides EcoRI‐restricted DNA library. Four probes showing polymorphisms among isolates within W‐type and R‐type and generating a total of 44 RFLPs were retained for cluster analysis. Two main groups were distinguished corresponding to W‐ and R‐types. The genetic diversity among isolates was greater for the W‐type than for the R‐type isolate, four and three distinct EcoRI‐restricted mitochondrial DNA patterns were identified in W‐ and R‐type isolates, respectively. The variability of profiles within each pathotype confirmed a higher degree of polymorphism in the W‐type.

“…When grown on potato dextrose agar (PDA), O. yallundae induces grey‐green colonies with smooth margins and a high growth rate and is more virulent to wheat and barley than to rye. By contrast, O. acuformis produces beige‐brown colonies with feathery margins and a slower growth rate but is equally pathogenic on wheat and rye (Thomas et al., 1992).…”

Section: Introductionmentioning

confidence: 99%

“…Previously published techniques for the detection and discrimination of the two species include isozyme polymorphism (Julian and Lucas, 1990); Southern blot hybridization using specific DNA probes (Thomas et al., 1992; Frei and Wenzel, 1993); serological methods (Unger and Wolf, 1988; Lind, 1990; Priestly and Dewey, 1993); restriction fragment length polymorphism (RFLP; Nicholson et al., 1991) and polymerase chain reaction (PCR) amplification of the ribosomal internal transcribed spacer (ITS) region (Poupard et al., 1993; Gac et al., 1996). None of these techniques is quantitative; Southern blot hybridization may not be sufficiently sensitive to detect Oculimacula spp.…”

Section: Introductionmentioning

confidence: 99%

Using Real‐time PCR to Discriminate and Quantify the Closely Related Wheat Pathogens Oculimacula yallundae and Oculimacula acuformis

Walsh¹,

Korimbocus²,

Boonham³

et al. 2005

Oculimacula yallundae and O. acuformis are the causal agents of eyespot disease of wheat and other cereals. The two fungi react differently to the application of fungicides, but they cannot be distinguished visually and their occurrence is often masked by other less damaging pathogens. Current methods to detect and distinguish Oculimacula species are impractical when testing large numbers of samples. A real-time polymerase chain reaction (PCR) assay, suitable for largescale testing, was developed and used for quantitative detection and discrimination of O. yallundae and O. acuformis. As the available DNA sequences differ by only a small number of conserved nucleotide polymorphisms, three different methods were investigated to achieve the desired specificity. A combination of mutagenically separated PCR and a shortened primer gave the best specificity for O. yallundae and O. acuformis, respectively. Although the comparison illustrated the practicalities of each method, it was not possible to devise a fixed set of rules for the design of primers to discriminate two closely related sequences; it is assumed that sequence context is an overriding and difficult to predict factor, and that a range of empirical approaches may need to be taken to reach the specificity required.