Genetic identity of Australian prickly acacia (Vachellia nilotica, Fabales: Mimosoideae) – Assessing the target for biological control

Prickly acacia (Vachellia nilotica) has been the target of biological control programmes in Australia for over three decades, with little success. Control efforts may have hindered by poor characterisation plants Australia, and ambiguous taxonomy species. Nine subspecies this weed described, only one identified (subsp. indica), though previous genetic screening a unique genotype that allegedly did not match any previously described (dubbed “Pakistan genotype”). We used gene sequencing to characterise assess native range distribution invasive subspecies. Two widespread ITS1 haplotypes were from 25 localities across northern corresponding subsp. indica undescribed genotype”. Many heterozygous at locus, indicating distinct genotypes are freely interbreeding. The genotype”, which no defining morphological characters, was found (including Ethiopia, where recently detected). genotype” is not, other words, subspecies, but simply represents variation within indica. No structuring indica, so precise provenance Australian could be determined. Future studies should use microsatellites or genotyping-by-sequencing approaches provide finer-scale assessment plants.