title: Immunolocalization of cyclotides in plant cells, tissues and organ supports their role in host defense.
abstract: The distribution of cyclotides was visualized in plant cells, tissues and organs using immunohistochemistry. Finding of cyclotides in tissues potentially vulnerable to pathogen attacks supports their role as defense molecules. The cyclotide family of plant peptides is characterized by the cyclic cystine knot motif and its diverse biological activities. Given their insecticidal and antimicrobial properties, the role of cyclotides in planta is probably associated with host defense. Our current understanding of the cellular compartmentalization of cyclotides in the vacuole is based on indirect studies on transgenic model plants that do not express cyclotides naturally. Matrix-assisted laser desorption ionization (MALDI) imaging has also been used to study the distribution of cyclotides, but the technique's resolution was insufficient to determine their tissue or cell distribution. To avoid the limitations of these approaches, immunohistochemical visualization methods were used. Antibodies were raised in rabbits using cycloviolacin O2 (cyO2), and their specificity was determined by Western and dot blot experiments. Slides for immunohistochemical analysis were prepared from leaf, petiole and root fragments of Viola odorata and Viola uliginosa, and specimens were visualized using indirect epifluorescence microscopy. The antibodies against cyclotides were specific against selected bracelet cyclotides with high similarity (cyO2, cyO3, cyO8, cyO13) and suitable for immunohistochemistry. The tissue distribution of the cyclotides visualized in this way is consistent with their proposed role in host defense-relatively large quantities were observed in the leaf and petiole epidermis in both Viola species. Cyclotides were also found in vascular tissue in all the assessed plant organs. The vacuole storage of cyclotides was directly shown.
authors.affiliation: W. Szafer Institute of Botany, Polish Academy of Science, 46 Lubicz St, 31-512, Cracow, Poland. b.slazak@botany.pl.|Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden. b.slazak@botany.pl.
authors.forename: Blazej
authors.initials: B
authors.lastname: Slazak
authors.affiliation: Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St, 80-308, Gdańsk, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Kapusta
authors.affiliation: Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden.
authors.forename: Sohaib
authors.initials: S
authors.lastname: Malik
authors.affiliation: Department of Plant Cytology and Embryology, Faculty of Biology, University of Gdańsk, 59 Wita Stwosza St, 80-308, Gdańsk, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Bohdanowicz
authors.affiliation: Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, 9 Gronostajowa St, 30-387, Cracow, Poland.
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Kuta
authors.affiliation: Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 7 Gronostajowa St, 30-387, Cracow, Poland.
authors.forename: Przemysław
authors.initials: P
authors.lastname: Malec
authors.affiliation: Division of Pharmacognosy, Department of Medicinal Chemistry, Uppsala University, Biomedical Center, Box 574, 751 23, Uppsala, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Göransson
mesh_terms: D000595:Amino Acid Sequence; D000906:Antibodies / Q000378:metabolism; D000918:Antibody Specificity / Q000276:immunology; D002451:Cell Compartmentation; D047169:Cyclotides / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D007150:Immunohistochemistry; D009928:Organ Specificity; D059828:Plant Cells / Q000378:metabolism*; D057865:Plant Immunity; D018515:Plant Leaves / Q000378:metabolism; D011485:Protein Binding; D032413:Viola / Q000276:immunology*
chemical_list: D000906:Antibodies; D047169:Cyclotides
keywords: Cyclotides; Host defense peptides; Immunohistochemistry; Viola