Taxonomy and genotypes of the Rubus fruticosus L. aggregate in Australia
K.J. EvansA, D.E. SymonB and R.T. RoushA
A Department of Crop Protection and CRC for Weed Management Systems, University of Adelaide, Waite Campus, PMB 1, Glen Osmond, South Australia 5064, Australia.
B The Botanic Gardens of Adelaide and State Herbarium, North Terrace, Adelaide, South Australia 5000, Australia.
Summary
Blackberry (Rubus fruticosus L. aggregate) is an important weed of agricultural and natural ecosystems in Australia. Weed managers require accurate taxonomic keys for Rubus so that they can identify which taxa are contributing to the weed problem. Blackberry comprises a few diploid sexual species (e.g. R. ulmifolius) and a large number of polyploid agamospecies (e.g. taxa in Australia named R. polyanthemus, R. laciniatus and the widespread R. affin. armeniacas (= R. discolor sensu auct. aust. non Weihe & Nees)).
We review the status of Rubus taxonomy in Australia and present some new information regarding existing taxa based on collections made in South Australia and examined by Rubus specialists in Europe. The utility of Rubus taxonomy for research workers and weed managers is also examined. Whereas the biological species concept may be useful for weed managers, research workers often require more precise information regarding the amount and distribution of genetic variation within Rubus. We present the use of DNA fingerprinting as a tool for (i) determining the genotype of an individual plant, (ii) estimating the genetic variation within and among Rubus taxa, and (iii) clarifying some taxonomic problems in the genus Rubus.
Twenty different genotypes were identified among 13 different Rubus taxa. No genetic variation was observed among 50 plants of R. affin. armeniacas sampled from 29 locations throughout Australia, suggesting that this common blackberry is probably a single clone. In contrast, seven different genotypes were observed among 26 plants of R. ulmifolius sens. lat. sampled from six locations in Victoria. Two of these genotypes were sampled from a single thicket of R. ulmifolius sens. lat. We illustrate the utility of genotyping Rubus plants in studies to identify virulent strains of the European rust fungus for improved biological control of blackberries.
Plant Protection Quarterly (1998) 13 (4) 152-156.