Carla Fernandes Cruz et. al V. 25, N o . 4, 2019 p. 443-449 1 State University of Mato Grosso, Tangará da Serra-MG, Brazil. 2 State University of Mato Grosso, Graduate Program in Genetics and Plant Breeding, Tangará da Serra-MG, Brazil. 3 State University of Mato Grosso, Department of Biology, Tangará da Serra-MT, Brazil. *Corresponding author: maurecilne@gmail.com 4 Federal University of Goiás, Institute of Biological Sciences, Jataí-GO, Brazil. Received Jul 16, 2019 | Accepted Nov 26, 2019 Licensed by CC BY 4.0 https://doi.org/10.1590/2447-536X.v25i4.2077 Scientific Article Ornamental Horticulture ISSN 2447-536X | httpS://orNameNtalhortIculture.emNuveNS.com.br/rbho In vitro regeneration and fowering of Portulaca grandifora Hook. Carla Fernandes Cruz 1 , Wolffe Ferreira dos Santos 1 , Claudinei da Silva Souza 1 , Marcelo Dias Machado 2 , Ilio Fealho de Carvalho 3 , Diego Ismael Rocha 4 , Maurecilne Lemes da Silva 3* Abstract P. grandifora is a known ornamental plant with abundant fowering. The fowers exhibit varied coloration with distinct forms and simple folded petals and/or multiple. The objective of this work was to induce regeneration via organogenesis and in vitro fower- ing of P. grandifora. Nodal segments of seedlings germinated in vitro were used as explant source for regeneration. Kinetin (KIN) and 6-Benzylaminopurine (BA) were used for the induction of organogenesis. The treatments supplemented with 1.0 and 1.5 mg L -1 BA induced the highest number of adventitious shoots with an average number of 7.0 (±1.55) e 5.4 (±0.83), respectively. The microcuttings obtained from regenerated shoots produced foral buds. The foral buds were located in the axillary and terminal re- gions of the microcuttings and developed in approximately 10 days of cultivation until the anthesis. The highest number of fower buds was observed in the presence of 0.75 mg L -1 of gibberellic acid. This study opens new perspectives for the establishment of biotechnological tools to be applied for this important ornamental species. Keywords: In vitro Flowering, Gibberellic acid, Shoot organogenesis. Resumo Regeneração e forescimento in vitro de Portulaca grandifora Hook P. grandifora é uma das plantas ornamentais com abundante foração de coloração variada com formas distintas e pétalas simples, dobradas e/ou múltiplas. O objetivo do trabalho foi induzir a regeneração pela via organogênica e o forescimento in vitro de P. grandifora. Segmentos nodais de plântulas germinadas in vitro foram utilizados como fonte de explante para a regeneração. Cine- tina (KIN) e 6-Benzilaminopurina (BA) foram utilizadas para a indução de organogênese de novo. Os tratamentos suplementados com 1.0, 1.5 mg L -1 de BA induziram a formação de maior número de brotações adventícias com número médio de 7.0 (±1,55) e 5.4 (±0.83), respectivamente. As microestacas obtidas a partir de gemas regeneradas produziram botões forais. Os botões forais localizaram-se nas regiões axilar e terminal das microestacas e desenvolveram-se em aproximadamente 10 dias de cultivo até a antese. O maior número de botões forais foi observado na presença de 0.75 mg L -1 de ácido giberélico. Este estudo abre novas perspectivas para o estabelecimento de ferramentas biotecnológicas a serem aplicadas para essa importante espécie ornamental. Palavras chave: Florescimento in vitro, Ácido giberélico, organogênese. Introduction Portulaca grandifora Hook. commonly known as “ten o’clock”, is one of the most widely cultivated annual fower plants in the tropical world by virtue of its easy cultivation, abundant fowering and fowers of varied colors such as red, yellow, pink, purple, white, orange and/or mixed. It is also found in distinct forms, with simple, folded, or multiple petals (Jain and Bashir, 2010). This ornamental plant can be grown in small spaces, gardens and pots. Additionally, P. grandifora is an important medicinal plant with putative immunostimulatory and detoxifying activity in hepatitis B (Chavalittumrong et al., 2007). Because of the ornamental potential of this plant, in vitro micropropagation and regeneration systems have been established for Portulaca species and have become relevant additional tools for their commercial production. The main regeneration pathway of P. grandifora is organogenesis, which is induced mainly from nodal explants and stem apices grown in the presence of cytokinin (Srivastava and Joshi, 2009; Jain and Bashir, 2010). In vitro fowering is probably one of the most fascinating processes in the development of plants in this culture system (Teixeira da Silva et al., 2014). The in vitro fowering process is a tool that can be applied for basic studies of fowering, reproduction, initiation and development of