The orchid seed coat: a developmental and functional perspective

Abstract

Orchid seeds are 'dust-like.' The seed coat is usually thin, with only one to a few cell layers. It originates from the integuments formed during ovule development. In orchids, the outer integument is primarily responsible for forming a mature seed coat. The inner integument usually fails to develop after fertilization, becomes compressed, and collapses over the expanding embryo. Hence, the seed coat is formed from the funiculus, chalaza, and outer integumentary cells. The outermost layer of the seed coat, the testa, is lignified, usually at the radial and inner tangential walls. The subepidermal thin-walled layer(s), the tegmen, subsequently cold, resulting in seeds having only a single layer of seed coat cells. In some species, cells of the inner integument remain alive with the ability to synthesize and accumulate lipidic and or phenolic compounds in their walls covering the embryo. This cover is called the 'carapace,' a protective shield contributing to the embryo's added protection. A developmental and functional perspective of the integuments and seed coat during seed development and germination is presented in this review.

Genome-Wide Identification, Expression, and Molecular Characterization of the CONSTANS-like Gene Family in Seven Orchid Species

“…For instance, the Cymbidium gynostemium-like perianth variety will lose its floral scent [56,87], while the regulation of gynostemium development may be influenced by CsiCOLs. Moreover, a majority of orchids produce exceedingly minuscule seeds, often described as 'dust-like' [88,89]. Intriguingly, recent research has uncovered that the COL gene has the potential to govern seed size in plants [90,91].…”

Deterioração controlada para avaliar a qualidade fisiológica de sementes de Brachiaria brizantha comercializadas

“…Diante desses resultados, os lotes 2 e 3 foram caracterizados como de qualidade superior seguidos do lote 4 como intermediário, e o lote 1, considerado como o lote de qualidade inferior (Tabela 2). A umidade e o peso das sementes estão diretamente relacionados com o processo de germinação, uma vez que, a disponibilidade de água é fundamental para a ativação e manutenção do metabolismo das sementes (Bewley et al, 2013), ativando as enzimas (Rasera e Castro, 2020;Pompelli et al, 2023) que irão mobilizar as substâncias de reservas armazenadas nas sementes que são fundamentais para o crescimento do embrião (Miray et al, 2021;Lee;Yeung, 2023).…”