Resumen Introducción: La falta de conocimiento sobre la germinación de semillas y el establecimiento de plántulas es una de las principales limitaciones para la restauración de áreas degradadas, incluido el bosque seco tropical conocido como Caatinga. Objetivo: Evaluar la movilización de reservas y metabolitos secundarios durante estas etapas de desarrollo en Erythina velutina. Métodos: Las semillas fueron escarificadas, desinfectadas, embebidas, sembradas entre toallas de papel e incubadas bajo condiciones controladas. Cultivamos las plántulas hidropónicamente en un invernadero. Recolectamos los cotiledones en la imbibición de la semilla, la protrusión de la radícula, la emergencia del hipocótilo, la formación del gancho apical y la expansión de las hojas cordiformes, la primera y segunda hoja trifoliada. Resultados: Las semillas contenían 20 % de almidón, 14.5 % de proteínas de almacenamiento, 11.6 % de lípidos neutros y 5.7 % de azúcares no reductores en peso seco. Los azúcares solubles se consumieron desde la emergencia del hipocótilo hasta la formación del gancho apical. Las principales reservas se movilizaron desde la formación del gancho apical hasta la expansión de la primera hoja trifoliada. La actividad enzimática aumentó desde la mitad hasta el final del establecimiento de las plántulas, movilizando almidón, aceites y proteínas. Se detectaron derivados de terpenoides, flavonoides, ácidos fenólicos y alcaloides. Los flavonoides y los ácidos fenólicos estuvieron en casi todas las etapas y los derivados terpenoides desaparecieron en la expansión de las hojas cordiformes. Conclusión: Los azúcares solubles apoyan el crecimiento temprano de las plántulas; el almidón, los aceites y las proteínas se movilizan simultáneamente desde el establecimiento medio hasta el final por amilasas, lipasas y proteasas ácidas. Los cotiledones contienen metabolitos secundarios, que pueden actuar en la defensa de las plántulas. El alto contenido de reservas y los metabolitos secundarios en los cotiledones podría permitir que las plántulas de E. velutina toleren estrés, validando su uso en la restauración de áreas degradadas.

Abstract Introduction: The lack of knowledge on seed germination and seedling establishment is a main constraint for the restoration of degraded areas, including the tropical dry forest known as Caatinga. Objective: To assess reserve and secondary metabolite mobilization during seed germination and seedling establishment in Erythina velutina. Methods: We scarified, disinfected, imbibed, sown between towel paper, and incubated seeds under controlled conditions. We hydroponically cultivated seedlings in a greenhouse. We harvested cotyledons at seed imbibition, radicle protrusion, hypocotyl emergence, apical hook formation and expansion of cordiform leaves, first trifoliate leaf, and second trifoliate leaf. Results: Seeds contained approximately 20 % starch, 14.5 % storage proteins, 11.6 % neutral lipids, and 5.7 % non-reducing sugars on a dry weight basis. Soluble sugars were mainly consumed from hypocotyl emergence to apical hook formation, while major reserves were mobilized from apical hook formation to expansion of first trifoliate leaf. Enzymatic activity increased from mid to late seedling establishment, causing the mobilization of starch, oils, and proteins. Terpenoid-derivatives, flavonoids, phenolic acids, and alkaloids were detected. Flavonoids and phenolic acids were present at almost all stages and terpenoid-derivatives disappeared at expansion of cordiform leaves. Conclusion: Soluble sugars support early seedling growth, while starch, oils and proteins are simultaneously mobilized from mid to late establishment by amylases, lipases, and acid proteases. The cotyledons contain secondary metabolites, which may act in seedling defense. High content of reserves and presence of secondary metabolites in the cotyledons could enable E. velutina seedlings endure stress, validating their use in the restoration of degraded areas.

Resumo A mobilização de reservas e a utilização de metabólitos foram caracterizadas durante a germinação da semente e o estabelecimento da plântula em Pityrocarpa moniliformis, uma leguminosa endospérmica da Caatinga. As sementes foram germinadas sob condições controladas por quatro dias e as plântulas foram transferidas para hidroponia e mantidas em casa de vegetação durante quatro dias. As coletas foram realizadas em estágios fisiológicos distintos e reservas, metabólitos e atividades enzimáticas foram determinadas nas diferentes partes da plântula. Galactomananas armazenadas no endosperma e açúcares não redutores acumulados nos cotilédones foram mobilizados da germinação da semente à emergência do hipocótilo. Durante estes processos, a acumulação de açúcares redutores no endosperma coincidiu com o aumento do conteúdo de amido nos cotilédones e no eixo da plântula, indicando que os açúcares liberados das galactomananas podem ter sido utilizados na biossíntese do amido. A mobilização do amido e das proteínas de reserva nos cotilédones ocorreu mais tarde, do alongamento do hipocótilo à expansão dos cotilédones. A degradação do amido possivelmente sustentou a acumulação de amido e açúcares solúveis na raiz, enquanto a hidrólise das proteínas de reserva foi associada à acumulação de clorofilas nos cotilédones e à emergência da primeira folha. Assim, a mobilização das reservas exibe um padrão bifásico, permitindo o rápido estabelecimento da plântula como uma estratégia fisiológica para garantir a colonização do ambiente. moniliformis Caatinga processos tarde raiz folha Assim bifásico ambiente

Abstract Reserve mobilisation and metabolite utilisation were characterised during seed germination and seedling establishment in Pityrocarpa moniliformis, an endospermic legume from Caatinga. Seeds were germinated under controlled conditions for four days and seedlings were transferred to hydroponics and maintained at a greenhouse during four days. Samples were collected at distinct physiological stages and reserves, metabolites, and enzymatic activities were determined in different seedling parts. Galactomannans stored in the endosperm and non-reducing sugars accumulated in the cotyledons were mobilised from seed germination to hypocotyl emergence. During these processes, the accumulation of reducing sugars in the endosperm coincided with an increase in the starch content in the cotyledons and seedling axis, indicating that sugars released from galactomannans may have been utilised in starch biosynthesis. Starch and storage protein mobilisation in the cotyledons occurred later, from hypocotyl elongation to cotyledon expansion. Starch degradation possibly supported the accumulation of starch and soluble sugars in the root, while storage protein hydrolysis was associated with cotyledon greening and first leaf emergence. Accordingly, reserve mobilisation exhibits a biphasic pattern, enabling fast seedling establishment as a physiological strategy to ensure environmental colonisation. moniliformis Caatinga reserves metabolites parts nonreducing non emergence processes axis biosynthesis later expansion root Accordingly pattern colonisation