Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 5.08

FURTHER EVIDENCES FOR THE LINKAGE ASSOCIATION BETWEEN THE Ol-2 GENE OF RESISTANCE TO POWDERY MILDEW AND PCR-BASED MARKERS IN TOMATO

L. RICCIARDI*, C. DE GIOVANNI*, C. LOTTI**

*) Department of Agroforestry, Environmental Biology and Chemistry, Section of Genetics and Plant Breeding, University of Bari, Via Amendola 165/A, 70126 Bari, Italy

**) Faculty of Agriculture, University of Foggia, via Napoli 26, 71100 Foggia, Italy

Lycopersicum esculentum powdery mildew, molecular markers, marker-assisted selection

Tomato powdery mildew (Oidium lycopersicum) is a recently reported plant disease which has a world-wide spread. The establishment of resistant cultivars appears to be a sustainable way to control the disease and to decrease the requirement for artificial anti-fungal treatments.

A source of genetic resistance due to a recessive gene (ol-2) was found in an accession of Lycopersicon esculentum var. cerasiforme. Starting from this genetic material, in previous works we reported results both on the use of bulked segregant analysis (BSA) applied to an F₂ population segregating for the ol-2 gene, derived from the pair-cross between a powdery mildew resistant line of Lycopersicon esculentum var. cerasiforme and on the susceptible cultivar Super Marmande, and the identification and localization in the tomato map of a single RAPD marker (designated as OPU3₁₅₀₀) detected in the susceptible bulk. In this work we show the results on further identification of seven AFLP markers linked to the Ol-2 locus and on the conversion of the OPU3₁₅₀₀ and the AFLP in co-dominant CAPS markers. Furthermore, by means of a linkage analysis performed in the F₂ population, we report the estimation of the distance between those markers and the ol-2 gene.

The results obtained appear to be useful to develop marker-assisted selection aimed to set up improved lines of tomato resistant to powdery mildew.