A microsatellite study on outcrossing rates and contamination in an Eucalyptus globulus breeding arboretum

Abstract

Four pairs of microsatellite molecular polymorphism primers were used to analyse microsatellite fingerprints of 188 seedlings derived from an open-pollinated progeny grafted Eucalyptus globulus breeding arboretum in Victoria, south-eastern Australia. The microsatellite loci chosen for this study were highly polymorphic with the mean number of alleles per locus of 14.25. Individual mothers varied in their outcrosssing rate estimate from 15% to 95%, the overall outcrossing level in the arboretum was 47.9% and the contamination rate was 17.6%. The high selfing level was likely to result in marked inbreeding depression in the performance of open-pollinated seed lots. Open-pollinated seeds collected from such arboreta are not advisable because of its low genetic quality, although such arboreta may be useful for the seed production through large-scale manual pollination or collecting seeds only from trees or genotypes within the arboretum that have high outcrossing rates.