Abstract
Downy mildew on sweet basil (Ocimum basilicum L.) occurs worldwide. Contaminated seeds are considered as the primary inoculum source. So far no strategy to control the disease is available. Hence, the use of pathogen-free seeds is the only alternative to prevent disease outbreaks. Therefore, a rapid diagnostic method for seed testing is urgently needed. The sensitivity of a specific PCR method for direct detection of the downy mildew pathogen Peronospora belbahrii on basil samples, particularly on seeds, was evaluated. The applied PCR method proved to be very sensitive for direct detection of the pathogen on seeds and plant samples. The PCR detection limit of P. belbahrii in artificially infested seeds corresponded to the DNA amount of a single spore per seed. Additionally, the systemic spread of the pathogen from naturally infected seeds was investigated. The experiments showed that outgrowing basil plants were latently infected with the downy mildew pathogen, and the infection continued within the plant. Contaminated seeds were harvested from symptomless latently infected plants. These results support the implementation of PCR-based detection in a seed certification scheme and the necessity to control the pathogen on seeds. The PCR method can also be used for evaluation of pathogen control on seeds based on detection of the pathogen in outgrowing plants.
This is a preview of subscription content, log in via an institution to check access.
References
Adenle VO, Cardwell KF (2000) Seed transmission of maize downy mildew (Peronosclerospora sorghi) in Nigeria. Plant Pathol 49:628–634
Belbahri L, Calmin G, Pawlowski J, Lefort F (2005) Phylogenetic analysis and Real Time PCR detection of a presumably undescribed Peronospora species on sweet basil and sage. Mycol Res 109:1276–1287
Champion R, Mécheneau H (1979) Méthode de détection de Peronospora valerianellae, agent du Mildiou, sur les semences de Mâche (Valerianella locusta). Comparaison en culture des résultats obtenus. Seed Sci Technol 7:259–263
Corbiere R, Molinero V, Lefebvre A, Spire D (1995) Detection of pea downy mildew (Peronospora viciae) in seed lots by ELISA. Bulletin OEPP 25:47–56
Fink M, Kofoet A (2005) A two-dimensional stochastic model of downy mildew of radish. Ecol Model 81:139–148
Garibaldi A, Minuto G, Bertetti D, Gullino ML (2004) Seed transmission of Peronospora sp. of basil. J Plant Dis Protect 111:465–469
Gebhardt C, Ritter E, Debener T, Schachtschabel U, Walkemeier B, Uhrig H, Salamini F (1989) RFLP analysis and linkage mapping in Solanum tuberosum. Theor Appl Genet 78:65–75
Grosch R, Schneider JHM, Peth A, Waschke A, Kofoet A, Franken P, Jabaji-Hare SH (2007) Development of a specific PCR assay for the detection of Rhizoctonia solani AG 1-IB using SCAR primers. J Appl Microbiol 102:806–819
Ioos R, Laugustin L, Rose S, Tourvieille J, Tourvieille de Labrouhe D (2007) Development of a PCR test to detect the downy mildew causal agent Plasmopara halstedii in sunflower seeds. Plant Pathol 56:209–218
Jang P, Safeeulla KM (1990) Modes of entry, establishment and seed transmission of Peronospora parasitica in radish. Proc Indian Acad Sci Plant Sci 100:369–373
Landa BB, Montes-Borrego M, Munoz-Ledema FJ, Jimenez-Diaz RM (2007) Phylogenetic analysis of downy mildew pathogens of opium poppy and PCR-Based in planta and seed detection of Peronospora arborescens. Phytopathology 97:1380–1390
Patzak J (2005) PCR detection of Pseudoperonospora humuli and Podosphaera macularis in Humulus lupinus. Plant Prod Sci 41:141–149
Ploch S, Thines M (2011) Obligate biotrophic pathogens of the genus Albugo are widespread as asymptomatic endophytes in natural populations of Brassicaceae. Mol Ecol 20:3692–3699
Schearer HJ, Penzkofer M, Reents H-J, Braendle F (2009) Saatgut-Testmethoden für Falschen Mehltau an Feldsalat. Werte-Wege-Wirkungen: Biolandbau im Spannungsfeld zwischen Ernährungssicherung, Markt und Klimawandel. Beiträge zur 10. Wissenschaftstagung Ökologischer Landbau, ETH Zürich
Thines M, Telle S, Ploch S, Runge F (2009) Identity of the downy mildew pathogens of basil, coleus, and sage with implications for quarantine measures. Mycol Res 113:532–540
Tinker NA, Fortin MG, Mather DE (1993) Random amplified polymorphic DNA and pedigree relationship in spring barley. Theoret Appl Genet 85:976–984
Tsay JwuGuh, Chu ChiShih, YaHan C, Chen RS (2006) Specific detection of Peronospora tabacina by PCR-amplified rDNA sequences. Plant Pathol J 5:378–382
Valsesia G, Gobbin D, Patocchi A, Vecchione A, Pertot I, Gessler C (2005) Development of a high-throughput method for quantification of Plasmopara viticola DNA in grapevine leaves by means of quantitative real-time polymerase chain reaction. Phythopathology 95:672–678
Acknowledgments
The authors thank Sieglinde Widiger, Sabine Breitkopf and Mandy Heinze for valuable technical and practical assistance. We are also grateful to the colleagues of the institute who supported the horticultural work. This research was supported by the Federal Office for Agriculture and Food (BLE, Germany).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Djalali Farahani-Kofoet, R., Römer, P. & Grosch, R. Systemic spread of downy mildew in basil plants and detection of the pathogen in seed and plant samples. Mycol Progress 11, 961–966 (2012). https://doi.org/10.1007/s11557-012-0816-z
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11557-012-0816-z