BA-Induced shoot development and proteomic-hormonal modulation in Albizia lebbeck in vitro propagation

Laíse Trugilio Moreira Marinho1, Yrexam Rodrigues de Souza Ribeiro1, Jociel Nascimento de Noronha1, Tadeu dos Reis Oliveira1, Renan Carrari dos Santos1, Vanildo Silveira2, Claudete Santa Catarina1

1. LBCT / CBB / UENF, Laboratório de Biologia Celular e Tecidual (LBCT) / Centro de Biociências e Biotecnologia (CBB) / Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF); Av. Alberto Lamego, 2000 - Parque Califórnia (Campos dos Goytacazes, RJ)
2. LBT / CBB / UENF, Laboratório de Biotecnologia (LBT) / Centro de Biociências e Biotecnologia (CBB) / Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF); Av. Alberto Lamego, 2000 - Parque Califórnia (Campos dos Goytacazes, RJ)

Albizia lebbeck is a tropical tree species of ecological and medicinal importance, widely used in reforestation programs. Due to its rapid growth, nitrogen-fixing ability, and production of bioactive compounds, this study aimed to evaluate the effects of 6-benzyladenine (BA) on shoot development from different nodal segments, along with associated changes in proteomic, hormonal, and polyamine (PA) profiles. Intermediate and apical nodal segments exhibited responsiveness to shoot development under 1 µM BA, whereas cotyledonary segments remained unresponsive. Responsive explants and their derived shoots accumulated higher levels of proteins related to the cell cycle, cell wall biosynthesis, the Calvin-Benson cycle, and energy metabolism (e.g., UBC core domain, tubulin beta chain, phosphoribulokinase, and chloroplastic triosephosphate isomerase) compared to unresponsive cotyledonary segments, supporting their role in acquiring competence for shoot development. Additionally, BA treatment induced the accumulation of proteins involved in proteolysis, cytoskeletal remodeling, and energy metabolism (such as proteasome subunit beta type-1, malate dehydrogenase, succinate dehydrogenase, and transketolase) particularly in elongated shoots. BA also modulated PA and hormone levels: it increased putrescine and spermidine while decreasing indole-3-acetic acid, abscisic acid, and jasmonic acid in shoots from responsive explants, compared to those from unresponsive ones. These findings suggest that hormonal crosstalk plays a role in regulating in vitro morphogenic competence and that BA significantly influences shoot development. This study provides valuable insights into the physiological and molecular mechanisms underlying shoot regeneration and offers an effective strategy for the in vitro propagation of A. lebbeck, supporting its use in conservation and reforestation initiatives.

Agradecimentos: CNPq, FAPERJ and CAPES.