TY - JOUR

T1 - Screening for resistance to downy mildew and its early detection in roses

AU - Schulz, D. F.

AU - Debener, T.

PY - 2007

Y1 - 2007

N2 - A resistance screening method was developed with defined conidia concentrations of Peronospora sparsa in a detached leaf assay. Disease severity was estimated microscopically by a five-step classification scheme based on the production of conidophores on the lower side of the leaf. With this method, a resistance screening was performed among several wild rose accessions and garden rose cultivars and 13 highly resistant accessions could be identified, which only occur among wild species. These accessions can be used to introgress resistance genes into breeding material. For the early detection of P. sparsa, a highly sensitive PCR based detection method was developed based on published primers and specific primers based on genomic DNA of P. sparsa after random priming with 34 different 15 to 20 meres. With the published ITS specific primers, we could detect pathogen DNA at a concentration of about 0.1 pg with primer PS 1/3. With primer PR 3/4, the sensitivity was tenfold higher but the specificity was lower. With our own designed specific primers, we could demonstrate in first tests that they could be useful for the detection of downy mildew in leaf samples. An ELISA using polyclonal antisera against P. sp a r s a was established as the second approach to detect the pathogen in the plant. It allows also the quantification of the pathogen. The detection limit for protein of P. sparsa in rose leaf extract was estimated at 10 ng/ml. The visual- and the serological detection methods were used in parallel to compare the correlation between the symptomatic leaf area and the ELISA readings in field-infested plants. A strong correlation was found between the infestation of the leaves and the protein content of P. sparsa.

AB - A resistance screening method was developed with defined conidia concentrations of Peronospora sparsa in a detached leaf assay. Disease severity was estimated microscopically by a five-step classification scheme based on the production of conidophores on the lower side of the leaf. With this method, a resistance screening was performed among several wild rose accessions and garden rose cultivars and 13 highly resistant accessions could be identified, which only occur among wild species. These accessions can be used to introgress resistance genes into breeding material. For the early detection of P. sparsa, a highly sensitive PCR based detection method was developed based on published primers and specific primers based on genomic DNA of P. sparsa after random priming with 34 different 15 to 20 meres. With the published ITS specific primers, we could detect pathogen DNA at a concentration of about 0.1 pg with primer PS 1/3. With primer PR 3/4, the sensitivity was tenfold higher but the specificity was lower. With our own designed specific primers, we could demonstrate in first tests that they could be useful for the detection of downy mildew in leaf samples. An ELISA using polyclonal antisera against P. sp a r s a was established as the second approach to detect the pathogen in the plant. It allows also the quantification of the pathogen. The detection limit for protein of P. sparsa in rose leaf extract was estimated at 10 ng/ml. The visual- and the serological detection methods were used in parallel to compare the correlation between the symptomatic leaf area and the ELISA readings in field-infested plants. A strong correlation was found between the infestation of the leaves and the protein content of P. sparsa.

KW - ELISA

KW - PCR

KW - Polyclonal antibodies

KW - Resistance sources

KW - Rosa

KW - Wild roses

UR - http://www.scopus.com/inward/record.url?scp=59449101683&partnerID=8YFLogxK

U2 - 10.17660/ActaHortic.2007.751.22

DO - 10.17660/ActaHortic.2007.751.22

M3 - Article

AN - SCOPUS:59449101683

VL - 751

SP - 189

EP - 198

JO - Acta Horticulturae

JF - Acta Horticulturae

SN - 0567-7572

ER -