ABSTRACT
We describe isoenzymes variability in six populations of Grevillea robusta from a provenances and progenies test established in a randomized block design with five plants per replication in Southern Brazil. The population genetic structure was examined by using biochemical markers in 5-year old trees, specifically at MDH-3, PGM-2, DIA-2, PO-1, PO-2, SOD-1, and SKDH-1 loci. The northern provenances (Rathdowney and Woodenbong) showed a strong divergence in relation to the average of provenances when alleles per locus (Ap), allele richness (Rs), Nei's gene diversity (H), and inbreeding coefficient (f) were considered. Inbreeding in varying degrees was detected. The commercial control showed the highest inbreeding coefficient, (f = 0.4448), whereas the provenance average was f = 0.2306, possibly due to insufficient sampling of populations in their origin (Australia). Despite its restricted natural range, a positive correlation between genetic divergence and geographic distance among original populations was detected. Genetic distance and cluster analyses based on the Bayesian model revealed three distinct provenance groups: 1) Rathdowney-QLD and Woodenbong-QLD; 2) Paddy's Flat-NSW; and 3) Mann River-NSW, Boyd River-NSW and the commercial control (material used in Brazil). The grouping of the control to both Mann River-NSW and Boyd River-NSW provenances suggests that the northern provenances have the highest potential for genetic improvement of wood productivity in Brazil, due to their high genetic diversity and low inbreeding coefficient.
Keywords:
Isoenzymes; Provenances/progenies trial; Tree breeding
