Sequence Characterization and Expression Analysis of Three APETALA2-like Genes from Saffron Crocus Athanasios S. Tsaftaris & Konstantinos Pasentsis & Panagiotis Madesis & Anagnostis Argiriou Published online: 16 September 2011 # Springer-Verlag 2011 Abstract To further understand flowering and flower organs formation in the monocot crop saffron crocus (Crocus sativus L.), we cloned three APETALA2-like cDNA sequences of the AP2/ERF transcription factor family designated CsatAP2a/b/c as well as the respective promoter region sequences. Bioinformatics analysis with putative orthologous sequences from various plant species suggested that all three cDNA sequences encode for AP2- like proteins with the AP2 characteristic motifs and amino acids. Phylogenetically, the isolated sequences were closest to the AP2-like genes from Pisum sativum, Arabidopsis thaliana and Oryza sativa. Expression analysis indicated that the isolated C. sativus sequences were expressed in all the examined organs. Expression of CsatAP2a/b/c cDNAs was also compared in wild-type and mutant C. sativus flowers lacking stamens or carpels. Sequence analysis of the promoter revealed the presence of putative binding motifis for CCAAT, AP2 and LEAFY transcription factors indicative of regulation by developmental signals. Keywords APETALA2 . Crocus sativus . Flowering . miR172 Introduction Throughout their lives, plants progress through distinct developmental phases, from germination and vegetative growth to flowering and, finally, senescence. Among them, flowering is of particular importance because the correct timing of this switch is mandatory to ensure reproductive success. Plants have therefore evolved an elaborate genetic network that coordinates endogenous and environmental signals to guarantee that flowering commences when conditions are most favorable (Distelfeld et al. 2009). Major roles in this network play regulatory transcription factors which coordinate the expression of key genes regulating flowering. Among others, regulatory compo- nents belonging to the AP2/EREBP) family of transcription factors were found in many plant species (Gao et al. 2010; He and Wang 2007; Wang et al. 2011) to regulate different aspects of plant development and its interaction with the environment, including the repression of flowering, hormone signaling, sugar and redox signaling in context of abiotic stresses such as cold and drought (Chuck et al. 2008; Dietz et al.; Jofuku et al. 2005; Xiong et al. 2011; Yuan et al. 2009) as well as biotic stress (Li et al. 2010). The common characteristics of these proteins is a sequence of about 70 amino acids that is highly conserved among all members of the family and comprises a new type of DNA binding domain, found mainly in plant species, the so-called AP2 domain (Shigyo et al. 2006; Weigel 1995). AP2/EREBP transcription factors are classified into two subfamilies with the division based in the number of copies of the AP2 domain in their sequence. The APETALA-2 (AP2) subfamily is composed of proteins that contain two AP2 repeats or the AP2 domain like Arabidopsis thaliana APETALA2 and AINTEGUMENTA, maize GLOSSY15 and the ids1, whereas the EREBP subfamily consists of proteins with only one repeat of this domain such as Electronic supplementary material The online version of this article (doi:10.1007/s11105-011-0355-9) contains supplementary material, which is available to authorized users. A. S. Tsaftaris : K. Pasentsis : P. Madesis : A. Argiriou Institute of Agrobiotechnology, CERTH, 6th Km Charilaou Thermi Road, Thermi, 570 01 Thessaloniki, Greece A. S. Tsaftaris (*) Department of Genetics and Plant Breeding, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece e-mail: tsaft@certh.gr Plant Mol Biol Rep (2012) 30:443–452 DOI 10.1007/s11105-011-0355-9