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 - 2.51

MOLECULAR GENOTYPING OF SOLANACEAE WILD SPECIES FOR RESISTANCE GENES

M.R. ERCOLANO, S. MELITO, R. LANGELLA, A. BARONE, L. FRUSCIANTE

Dept. Soil, Plant and Environmental Sciences, Via Università 100, 80055 Portici, Italy

PCR-marker, Solanaceae, resistance genes, wild species, genetic diversity

The wild Solanaceae species represent an important source of resistance genes to biotic stresses. Numerous genes for resistance to important pests and diseases have been already identified and characterized in such germoplasm. Moreover Recent advances in plant biology and plant-pathogens interactions have resulted in development of new approaches for gene identification. Molecular analysis of plant resistance gene based on sequence homologies showed that they are organized in large multigene family. The characterization of plant resistance allelic diversity could be an important step for genetic improvement of Solanaceae cultivated species. The aim of the present work was to genotype various accessions of Lycopersicon and Solanum genetic resources for the allelic diversity in four resistance genes. In particular, 13 accession belonging to 8 Solanum species and 15 Lycopersicon hirsutum were tested accessions a primer-set related to resistance genes. Specific PCR primers were designed using sequences of 4 resistance genes: Pto (a serine-threonine protein kinase) conferring resistance to isolates of Pseudomonas syringae, I₂ (a leucine rich repeat protein) conferring resistance to plant vascular disease caused by Fusarium oxysporum f sp. lycoprersici, Sw-5 conferring resistance against the tomato spotted wilt virus, R1 (nucleotide binding domain, leucine-rich repeat) conferring resistance to Phytophthora infestans.

Amplified fragments obtained with R1specific primers differed for number and size. A total of 15 bands ranging from 200 to 1500 bp were generated. Six tomato accessions amplified a fragment corresponding to the expected size of 1400 bp. For Pto, I₂ and Sw-5 the presence of polymorphic site potentially differentiating homologues genes were recognized thought restriction enzyme analysis of PCR products. A good level of allelic polymorphism was detected. In particular the Pto specific primers in tomato gave a amplified fragment of 1600 bp that after digestion produced the expected restriction pattern in three accession whereas in potato a fragment of 600 bp was generated. Sequencing and analysis of the PCR fragments is in progress.