GENOTYPE DIVERSITY OF SALSOLA TRAGUS AND POTENTIAL ORIGINS OF A PREVIOUSLY UNIDENTIFIED INVASIVE SALSOLA FROM CALIFORNIA AND ARIZONA

Abstract

Various Salsola spp. have been introduced to the USA, and some of these are considered noxious or invasive in certain regions. The genus is taxonomically challenging, and recent morphological, cytological, and molecular work has shown that an unknown taxon, previously identified as S. tragus, but recently temporarily designated as Type B, with unknown origins, exists in California and Arizona. Type B's origins and identity are a point of concern for biological control efforts, as it is much less affected by fungal biological control agents than the sympatric invasive S. tragus. Initial studies in 2005 indicated that Type B is morphologically very similar to S. kali subsp. austroafricana which has been collected in southern Africa. Here we use DNA sequence data from a PEPC intron to compare USA and Old World specimens, and results indicate that S. kali subsp. austroafricana is genetically identical to Type B and distinct from S. tragus. It is unclear if S. kali subsp. austroafricana is native to southern Africa or to the northern hemisphere of the Old World, and further investigations in both regions are needed.