Microsatellite variation and assessment of genetic structure in tea tree (Melaleuca alternifolia– Myrtaceae)


  • These results are part of a broad study on the genotypic and phenotypic variation in tea tree. M. Rossetto developed and applied microsatellite markers in Melaleuca alternifolia; his main areas of interest are population and conservation genetics. R. Slade has broad interests in evolutionary and population genetics. R. Henry is the director of the Centre for Plant Conservation Genetics at Southern Cross University. The centre's mission is to provide focus for the practical application of molecular techniques to the conservation and utilization of plant genetic resources. P. Baverstock and L. S. Lee were directly involved in development and management of the tea tree project.

M. Rossetto, Fax: +61 2 6622 2080; E-mail: mrossett@scu.edu.au


Analysis of five microsatellite loci in 500 Melaleuca alternifolia individuals produced 98 alleles that were useful for population genetic studies. Considerable levels of observed heterozygosity were recorded (HO = 0.724), with ≈ 90% of the variability being detected within populations. A low level of selfing (14%) was suggested to be the principal cause of excess homozygosity in a number of populations (overall FIS = 0.073). This study showed low levels of inbreeding in certain populations as well as a significant isolation-by-distance model. Only two groups of populations (Queensland and New South Wales) constituted different genetic provenances as a result of geographical isolation. The M. alternifolia data suggest that microsatellite loci did not always arise by a stepwise mutation process but that larger jumps in allele size may be involved in their evolution.