Development of chloroplast microsatellite markers for giant ragweed (Ambrosia trifida)

Premise Plant invasions are increasing globally, and extensive study of the genetic background of the source and invading populations is needed to understand such biological processes. For this reason, chloroplast microsatellite markers were identified to explore the genetic diversity of the noxious weed Ambrosia trifida (Asteraceae). Methods and Results The complete chloroplast genome of A. trifida was mined for microsatellite loci, and 15 novel chloroplast primers were identified to assess the genetic diversity of 49 Ambrosia samples. The number of alleles amplified ranged from two to six, with an average of 3.2 alleles per locus. Shannon's information index varied from 0.305 and 1.467, expected heterozygosity ranged from 0.178 to 0.645, and the polymorphism information content value ranged from 0.211 to 0.675 (average 0.428). The cross-species transferability of the 15 microsatellite loci was also evaluated in four related Ambrosia species (A. artemisiifolia, A. maritima, A. psilostachya, and A. tenuifolia). Conclusions The novel chloroplast microsatellite markers developed in the current study demonstrate substantial cross-species transferability and will be helpful in future genetic diversity studies of A. trifida and related species.