Approcci biotecnologici per lo studio dei patosistemi pomodoro-Oidium neolycopersici e pomodoro-Phytophthora infestans
Faino, Luigi (2008) Approcci biotecnologici per lo studio dei patosistemi pomodoro-Oidium neolycopersici e pomodoro-Phytophthora infestans. [Tesi di dottorato] (Inedito)
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The first aim of this PhD thesis was to dissect the role of Quantitative Trait Loci (QTLs) involved in the resistance to Oidium neolycopersici identified in tomato wild species Solanum neorickii G1.1061. A F2 population and several advanced backcrosses (BC) originated from cross between S. neorickii and the susceptible S. lycopersicon cv Monyemaker, were used to fine map Ol-qtl2 and Ol-qtl3 loci using CAPS markers. The location of Ol-qtl2 on chromosome 12, narrowed down in a region of 8 cM, explains 30% of the phenotypic variation. Ol-qtl3 was a false positive. The Ol-qtl2 locus was associated to a region where the Lv gene (conferring resistance to Leveillula taurica) is located. To clone the QTL a genetic and physical mapping approach in the region of interest was performed. An epistatic locus that interact with the Ol-qtl2 on chromosome 3 of S. neorickii was also identified. The second aim was to explore the interaction system tomato-late blight. In particular, tomato plants transformed with the R1 gene were inoculated with the host and the non-host pathogen races. The R1 resistance gene transcribes for a protein that confer resistance to P. infestans race 1 in potato (Ballvora et al. 2002). A Suppression Subtractive Hybridization (SSH) was used to generate a cDNA library enriched for sequences transcriptin a resistant R1-tomato plants inoculated with late blight. A total of 100 clones were obtained and 82 partial cDNA sequences were submitted to international database (Solanaceae Genomic Network; SGN: http://www.sgn.cornell.edu and National Center for Biotechnology Information; NCBI: http://www.ncbi.nlm.nih.gov ). Fifty-six sequences showed similarity to plant annotated sequences. Of these, 39% were previously characterized as either defense- or stress-associated genes. A fine annotation was performed for each gene. The aim of this experiment was to understand which gene/s was/were involved in the signal transduction process during the interaction of R1 gene with the P. infestans race 1. Based on the annotation results, further analyses were conducted on ten clones. The sequences of these clones were used to design primers to perform Real Time PCR experiments. In particular, sequence 21 (Catalase_like), 37 (putative receptor-like serine-threonine protein kinase) and 47 (Beta glucosidase) gave the best results.
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