Is South African pompom weed (Campuloclinium macrophalum, Asteraceae) clonal? Evidence from ITS sequence data.

Is South African pompom weed (Campuloclinium macrophalum, Asteraceae) clonal? Evidence from ITS sequence data.
Lucy Gitonga1, Glynnis V Cron1, Andrew Mcconnachie2 & Marcus Byrne1
1School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Private Bag X3, WITS 2050, South Africa
2Agricultural Research Council-Plant Protection Research Institute, Private Bag X6006, Cedara, 3245, South Africa

Campuloclinium macrocephalum is a highly invasive alien weed in South Africa that is native to Central and South America but the exact origin of the South African populations is currently unknown. It is targeted for biological control but the success of bio-control agents will depend on host specificity and biotype compatibility to the full genetic diversity of pompom weed in South Africa. A total of 52 specimens from across South Africa,  14 specimens from Argentina and three from Brazil were sequenced for the nuclear ribosomal ITS regions. No genetic variation in the ITS regions was found among all the South African specimens sequenced. In the consensus tree resulting from Maximum Parsimony analysis using the ITS regions, one clade comprised all the South African specimens together with the Argentinean specimens and one specimen from Parana Province in Brazil, while two other Brazilian specimens formed a separate clade. Network analysis generated three haplotypes consistent with the phylogenetic tree. One haplotype is shared by all the South African specimens, one Brazilian specimen, and all the Argentinean specimens bar one from Corrientes, which has a unique haplotype. The third haplotype is shared by the two Brazilian specimens. The South African specimens represent a single clone throughout the introduced range that is possibly triploid. The likely origin of the genetically similar South African populations appears to be Argentina, suggesting that candidate biological control agents sampled from Argentina should be equally effective on all South African populations.