Intraspecific classification of Fragaria chiloensis: A molecular approach to germplasm protection and utilization.
|Title:||Intraspecific classification of Fragaria chiloensis: A molecular approach to germplasm protection and utilization.|
|Abstract:||Four subspecies of Fragaria chiloensis defined on a geographic basis have been proposed, but never supported with quantitative data; ssp. lucida and ssp. pacifica from North America, ssp. chiloensis from South America and ssp. sandwicensis from the Hawaiian Islands. The objective of the present research was to develop a classification that was both operational and an accurate portrayal of genetic relationships in order to achieve efficient protection and utilization of germplasm in crop improvement. Discriminant analysis based on 14 measurements in 95 herbaruim specimens revealed a distinct separation of ssp. sandwicensis: longer leaflets, longer hairs on the undersurface of the leaflets and more numerous leaflet veins. The South and North American plants were significantly different but overlapped to a degree, the former having 6-10 petals, instead of 5-6 (rarely 7). The two North American subspecies overlapped extensively with the only morphological distinction being hair type. DNA was removed from fresh leaf tissue of 54 plants and analysed using random amplified polymorphic DNA (RAPDs). From 100 primers screened, 12 were selected providing 68 scorable polymorphic bands. The phenogram (corphenetic correlation, $r = 0.97)$ based on UPGMA clustering of Jaccard's coefficients revealed a clear division between North and South American plants but only partial separation between the two North American subspecies. It is proposed that the two North American subspecies be reduced to the rank of forma. The resulting taxonomic change creates Fragaria chiloensis (L.) Duchesne ssp. lucida (E. Vilm) f. lucida and f. pacifica (Staudt) Catling & Porebski. Ssp. lucida and ssp. sandwicensis provide a valuable source of novel genes for incorporation into the crop. (Abstract shortened by UMI.)|
|Collection||Thèses, 1910 - 2010 // Theses, 1910 - 2010|