Biologia 70/10: 1326—1333, 2015 Section Botany DOI: 10.1515/biolog-2015-0151 Species delimitation and population structure in three Onosma (Boraginaceae) species Masoud Sheidai 1 *, Samira Sadeghi 1 , Mahnaz-Arab Ameri 1 , Ahmad-Reza Mehrabeian 1 & Zahra Noormohammadi 2 1 Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran; e-mail: msheidai@yahoo.com 2 Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran Abstract: The present study aimed to reveal genetic diversity and population structure in three Onosma species i.e., Onosma bulbotrichum DC., O. elwendicum Wettst. and O. sericeum Willd. (Boraginaceae) growing in Iran. This study was performed to check if the ISSR molecular markers could be used in the Onosma species delimitation. We also investigated the infra-specific morphological variability and if we can identify infra-species taxonomic forms. The present study revealed within species genetic and morphological diversity. ISSR data could delimit the studied species as they were separated from each other in NJ tree, maximum parsimony and STRUCTURE analysis. AMOVA and Hickory tests produced sig- nificant genetic difference among the studied species. The Mantel test showed no correlation between genetic distance and geographical distance of the populations for all three species. Reticulation analysis and Nm estimation showed gene flow among these populations. We could identify a few ISSR loci that are adaptive. Data obtained can be used in conservation of these medicinal plants in Iran. Key words: Onosma; adaptive loci; gene flow; ISSR. Introduction The genus Onosma L. (Boraginaceae) contains about 150 annual or perennial species Mehrabeian et al. 2012), occurring in dry, cliffy and sunny habitats. These species are distributed mainly in Eurasia and Mediter- ranean regions. Iran with about 37 species is considered to be the center of the genus distribution with max- imum number of Onosma species (Khatamsaz 2002; Mehrabeian et al. 2010, 2012). Onosma species have ornamental value (Onosma. alborosea, Onosma frutenscens,, and Onosma echioi- des), and medicinal uses (Onosma argentatumn, Onos- ma sericeum and Onosma microcarpum, Onosma bul- botrichum D.C., Onosma sericeum Willd.) (Tosun et al. 2008; Gohari et al. 2009; Badruddeen et al. 2012). The species description in the genus Onosma is highly controversial and many similar species were described on the basis of minor morphological differences (S ¸uteu et al. 2007; Mehrabian et al. 2012). Molecular studies in the genus are extensive; some include using amplified fragment length polymorphism (AFLP) (see for example, Mengoni et al. 2006; Kolarčik et al. 2014), combination of nrDNA sequence ITS1, cpDNA sequences and AFLP (S ¸uteu et al. 2012; Ko- larčik et al. 2010) and inter-simple sequence repeats (ISSRs) study (Mehrabian et al. 2011). Molecular study performed in Onosma echioides accessions collected from serpentine and calcareous soils (Mengoni et al. 2006), revealed a remarkable genetic dif- ferentiation between populations. It also revealed a high level of within-population genetic variability. The key factor shaping the infra-specific genetic structure of O. echioides, was the short-distance, zoochorous systems of seed dispersal and pollination in this species. Similarly, S ¸uteu et al. (2012) carried out taxonomic and genetic diversity studies of Onosma pseudoarenaria Schur. s. str., (often cited in taxonomic literature as O. pseu- darenaria) and Onosma arenaria Waldst. & Kit.) using nrDNA sequence ITS1, cpDNA sequences and AFLP molecular markers. The cpDNA data showed a genetic uniformity for most of the O. pseudoarenaria popula- tions while, AFLP showed an ongoing differentiation of the populations due to the present fragmented distri- bution. Onosma species determination and delimitation is not a simple task (Mehrabian et al. 2011). Molecular markers have been used to study genetic diversity, pop- ulation structure and species delimitation in different plant species (e.g., Sheidai et al. 2012, 2013). There- fore, the present investigation was performed to see 1) if ISSR multilocus molecular markers can be used in tax- onomy and species delimitation in the genus Onosma, 2) to study population structure in three medicinally * Corresponding author c 2015 Institute of Botany, Slovak Academy of Sciences Brought to you by | Weizmann Institute of Science Authenticated Download Date | 1/2/16 10:22 AM