title: Morpho-histodifferentiation of Billbergia Thunb. (Bromeliaceae) nodular cultures.
abstract: Nodule cultures are formed through an intermediate morphogenetic route that lies between organogenesis and somatic embryogenesis. Although well described in many species, different aspects of the morphological and histological development of nodules remain to be clarified. Based on their threatened status and high ornamental value, Billbergia alfonsi-joannis and Billbergia zebrina, two epiphytic bromeliad species endemic to the South American Atlantic Forest, were studied. Nodular cultures were induced to grow from nodal segments taken from etiolated seedlings grown in vitro for 12 weeks in the dark on MS medium supplemented with 1 μM TDZ. Samples were taken for analysis weekly over 8 weeks of growth and analyzed under light, transmission electron, and scanning electron microscopes. Morphological and histological analysis showed that nodular clusters originated from stem pericycles and consisted of a polycenter, cambial tissue, cortical parenchyma, and a covering tissue. The polycenter consisted of an organizational center dispersed in parenchymal tissue. Each organizational center was formed by a vascular system surrounded by a bundle sheath. A cambial tissue surrounded these polycenters, promoting the regeneration of new nodules and leading to the formation of buds and roots. Primary nodules could generate secondary nodules in a repetitive process. Thus, histological analysis revealed the origin and formation of nodular cultures. These new data will support the establishment of micropropagation protocols and regeneration on a large scale for these species.
authors.affiliation: Programa de Pós-Graduação em Recursos Genéticos Vegetais, Universidade Federal de Santa Catarina, Rod. Admar Gonzaga, Km 3, Florianópolis, SC 88034-001, Brazil. thaysiventura@gmail.com.|Instituto Federal de Educação, Ciência e Tecnologia Catarinense, Campus Camboriú, Rua Joaquim Garcia, sn, Camboriú, SC 88340-055, Brazil. thaysiventura@gmail.com.
authors.forename: Thaysi Ventura
authors.initials: TV
authors.lastname: de Souza
authors.affiliation: Departamento de Botânica, Universidade Federal de Santa Catarina, Campus Universitário, Florianópolis, SC 88040-900, Brazil.
authors.forename: Julia Faillace
authors.initials: JF
authors.lastname: Thiesen
authors.affiliation: Programa de Pós-Graduação em Recursos Genéticos Vegetais, Universidade Federal de Santa Catarina, Rod. Admar Gonzaga, Km 3, Florianópolis, SC 88034-001, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Lando
authors.affiliation: Programa de Pós-Graduação em Recursos Genéticos Vegetais, Universidade Federal de Santa Catarina, Rod. Admar Gonzaga, Km 3, Florianópolis, SC 88034-001, Brazil.
authors.forename: Miguel Pedro
authors.initials: MP
authors.lastname: Guerra
authors.affiliation: Programa de Pós-Graduação em Recursos Genéticos Vegetais, Universidade Federal de Santa Catarina, Rod. Admar Gonzaga, Km 3, Florianópolis, SC 88034-001, Brazil.|Departamento de Botânica, Universidade Federal de Santa Catarina, Campus Universitário, Florianópolis, SC 88040-900, Brazil.
authors.forename: Marisa
authors.initials: M
authors.lastname: Santos
mesh_terms: D031229:Bromeliaceae / Q000033:anatomy & histology* / Q000166:cytology* / Q000648:ultrastructure; D002454:Cell Differentiation; D008954:Models, Biological; D013045:Species Specificity; D046509:Tissue Culture Techniques / Q000379:methods*
keywords: Billbergia alfonsi-joannis; Billbergia zebrina; Histology; Micropropagation; Ultrastructure