ORIGINAL ARTICLE Interspecific genetic analysis of orchids in Brazil using molecular markers Cristiane Gouve ˆa Fajardo • Fa ´bio de Almeida Vieira • Wagner Franco Molina Received: 4 November 2013 / Accepted: 2 February 2014 Ó Springer-Verlag Wien 2014 Abstract Several species of Orchidaceae, one of the largest plant families, are considered endangered through- out South America and legal protection policies are needed so they can be preserved. Inter simple sequence repeats (ISSRs) markers are a potential tool to be used in the phy- logenetic reconstruction of closely related species. In this study, we evaluate the polymorphic information content (PIC) and optimum number of ISSR markers (ONM) for five Laeliinae orchids in order to assess genetic diversity. The phylogenetic relationships between Cattleya granu- losa, an endangered Brazilian orchid, and four other native Brazilian species (Brassavola tuberculata, Cattleya bicolor, Cattleya labiata and Cattleya schofieldiana) were analyzed for genetic diversity and differentiation. The 11 selected primers generated 166 unambiguous loci (PIC = 0.354; ONM = 156). Of the five studied species, C. bicolor exhibited the highest level of genetic diversity (H E = 0.219), while C. labiata exhibited the lowest level (H E = 0.132). The percentage of genetic variation among species (analysis of molecular variance) was 23.26 %. The principal component analysis (PCA) of ISSR data showed that unifoliate and bifoliolate species are genetically divergent. Additionally, PCA indicated a close relation between C. granulosa and C. schofieldiana, a species con- sidered to be a variety of C. granulosa by many researchers. Thus, we conclude that ISSR genetic markers are effective in detecting genetic differentiation among orchid species. Keywords Brassavola tuberculata  Cattleya  ISSR  Genetic differentiation  Laeliinae  Orchidaceae Introduction With approximately 24,000 recognized species and about 800 genera, Orchidaceae is one of the largest plant families (World Checklist of the Monocotyledons 2006). The family presents some of the most complex and intriguing pollination mecha- nisms ever recorded (Lovisa et al. 2010) and its flowers are pollinated by diverse groups of insects and birds (Dodson et al. 1969). Within this family, Laeliinae is a strictly Neotropical subtribe with approximately 1,500 species and around 50 genera; it is the second largest subtribe of Orchidaceae (van den Berg et al. 2009). While artificial hybridization can be employed to combine various genera for horticultural pur- poses, many interspecific and intergeneric hybrids have also been found in natural habitats (Azevedo et al. 2006; van den Berg et al. 2009; Pinheiro et al. 2010; Storti et al. 2011). Hybridization in nature has been documented through the identification of several intra- and intergeneric species, espe- cially involving Cattleya, one of the most economically important genus. Throughout South America, several species of this genus are considered endangered (MMA 2008) and legal policies for their protection are necessary. Inter simple sequence repeats (ISSRs) have been used extensively to characterize genetic diversity in orchids, C. G. Fajardo (&) Departamento de Bota ˆnica, Ecologia e Zoologia, Universidade Federal do Rio Grande do Norte, Natal, RN CEP 59078-970, Brazil e-mail: genegoista@yahoo.com.br F. de Almeida Vieira Unidade Acade ˆmica Especializada em Cie ˆncias Agra ´rias, Universidade Federal do Rio Grande do Norte, Macaı ´ba, RN CEP 59280-000, Brazil W. F. Molina Departamento de Biologia Celular e Gene ´tica, Universidade Federal do Rio Grande do Norte, Natal, RN CEP 59078-970, Brazil 123 Plant Syst Evol DOI 10.1007/s00606-014-1009-9