As sementes de Eugenia spp. (Myrtaceae) e seus novos conceitos sobre propagação

Abstract

RESUMO O comportamento padrão esperado para as sementes, seja por leigos ou mesmo especialistas no assunto, é o de uma estrutura seca que, colocada em meio com suficiente disponibilidade de água, germina e produz uma nova planta, preservando a espécie. Contudo, há um gigantesco número de espécies que possuem sementes com comportamento totalmente diferente. Sementes que não podem sequer serem secas, denominadas recalcitrantes, são dispersas úmidas no meio e, ao longo da evolução das espécies, desenvolveram sistemas alternativos àqueles padrões esperados. Nesta revisão, procuramos demonstrar um dos mais complexos e interessantes sistemas de preservação de espécies com sementes recalcitrantes, nas espécies do gênero Eugenia, da família Myrtaceae. São abordados tanto a capacidade em regenerar embriões a partir de tecidos cotiledonares, quanto o controle extremamente eficiente em não desperdiçar material de reserva, evitando germinações simultâneas na mesma semente. Neste controle parecem estar envolvidas as espécies reativas de oxigênio (EROs), que também são revistas neste artigo.

Regeneration of roots and seedlings from Eugenia involucrata seeds under water deficit conditions

“…regeneration mechanisms of the Eugenia species (Amorim et al, 2020) to produce new roots and/or shoots. However, the great majority of the germinant seeds under 30 days of water deficit did not need to make use of this tool, but were able to continue development of the already existing roots.…”

The metabolic profiles of Eugenia astringens and E. uniflora (Myrtaceae) sensitive seeds affect desiccation

“…1100 species) and is widely distributed in Brazil (Vasconcelos et al, 2017). Several native Eugenia species are known for their ecological, nutritional and pharmaceutical potential (Mazine et al, 2016, Araújo et al, 2019, Amorim et al, 2020.…”

“…1100 species) and is widely distributed in Brazil (Vasconcelos et al, 2017). Several native Eugenia species are known for their ecological, nutritional and pharmaceutical potential (Mazine et al, 2016, Araújo et al, 2019, Amorim et al, 2020). Moreover, Eugenia seeds present the unusual trait at which fractioned seeds are still able to originate a normal seedling (Alonso and Barbedo, 2020).…”

“…Despite the relevance of this genus, the seed physiological behaviour under desiccation is not completely understood. What seems to be a consensus is that Eugenia seeds are somewhat DS (Delgado and Barbedo, 2007, Amorim et al, 2020, Rodrigues et al, 2022). There are no reports of Eugenia DT‐seeded species to date, but the DS degree varies between Eugenia species and even among distinct populations, seemingly to be affected by seed provenance (Lamarca et al, 2011 and 2013, Pereira et al, 2017, Rodrigues et al, 2022).…”

Storage of recalcitrant seeds of Eugenia brasiliensis Lam. under control of water availability

“…Recalcitrant seeds (sensitive to desiccation) usually show intense metabolic activity even after their dispersion and may even germinate during storage. The high water content and this intense metabolic activity, when germination is not completed, create favorable conditions for rapid deterioration (Castro et al, 2004;Barbedo et al, 2013;Amorim et al, 2020). Thus, the conservation of viability during the storage of recalcitrant seeds remains one of the greatest challenges for seed science.…”