CHARACTERIZATION OF CAMELINA SATIVA GENOME, AN OILSEED PLANT, THROUGH A COMBINED APPROACH BASED ON THE Β-TUBULIN GENE FAMILY AND MICROSATELLITE MOLECULAR MARKERS

ABSTRACT The study reported in this thesis was performed in order to increase our knowledge on Camelina sativa genome and on the degree of the genetic polymorphism and relatedness present within a collection of camelina accessions. This aim has been pursued trough the characterization of the β-tubulin gene family and the use of novel and specific SSR markers. The β-tubulin gene family of C. sativa has been isolated, cloned and characterized using the h-TBP method. This technique allows the rapid cloning of the β-tubulin genomic sequences that encompass the two introns, invariantly present at fixed positions within the coding region of the vast majority of the plant species. We have found that in C. sativa this family was composed of at least 20 different β–tubulin isotypes, named CsTUB1 through CsTUB20. This large number of β–tubulin is an indication that C. sativa (chromosome number 2n = 40) might be a polyploid species. The phylogenetic tree obtained from the β-tubulin coding sequences of C. sativa and A. thaliana has shown a distribution of CsTUBs that is spread throughout the clusters without distinction between A. thaliana and C. sativa. Then, we reported the isolation and characterization of specific camelina microsatellite markers by using one C. sativa (GA)-SSR-enriched library. All SSR markers utilised in this study produced clear and unambiguous amplification fragments permitting the detection of a large number of alleles per locus. A total of 134 alleles were generated at 15 SSR loci in the germplasm analysed with a mean of 8.93 alleles per locus. The high discriminatory capacity of the SSR markers, as observed in other plant species, have also been confirmed in our study, in fact in our camelina collection thirty-eight out of forty accessions are clearly distinguished by the 15 polymorphic microsatellites used. In addition, a certain degree of association among the SSR camelina sub-groups and some of the evaluated agronomic/biochemical traits has been observed. In conclusion, knowledge of genetic variation and the genetic relationship between genotypes is important for an efficient utilisation of C. sativa germplasm resources. Beside of providing a useful tool for germplasm identification and genetic diversity, these 15 newly developed SSR polymorphic markers will prove very useful in genetic mapping and in assisting plant breeders in early progeny selection.