Molecular identification ofSolanum elaeagnifolium in Australia using DNA barcoding, a solution for better management

摘要

The problematic weed silverleaf nightshade (Solatium elaeagnifolium Cav.) was introduced to Australia during the early 20th century from North America and has since emerged as a Weed of National Significance. This species is almost impossible to eradicate after establishment, with its management in areas of new emergence therefore much aided by prompt identification and early action. Identification of the weed is often confounded because of the weed's remarkable similarity (especially pre-floral stages) to a variety of native Solanum species. DNA barcoding for improved identification may therefore improve its management. Sequences of the nuclear waxy gene and two chloroplast genes (matK and trnL-trnF) were compared among S. elaeagnifolium (N = 12) and 10 native species (S. brownii, S. centrale, S. coactiliferum, S. esuriale, S.jucimdwn, S. lasiophyllum, S. lithophyl-lum, S. petrophilum, S. quadriloculatum and S. stur-tianum) with which the weed is commonly confused. A further five species includingS. campanulatum, S. chenopodinum, S. cleistogamum, S. nummularium and S. succosum, were also analysed to provide a wide cross-section of Australian native species. Clear and well supported genetic separations of all species were evident at each of the three gene regions. The maximum observed genetic distance in S. elaeagnifolium was 0.41%, and the minimum distance to its nearest genetic neighbour species was 1.12%. Our study provides a reliable genetic tool for S. elaeagnifolium identification irrespective of developmental stage, assisting efficient management aimed at reducing the risk of further spread of this weed to new areas.