Institute of Subtropical and Mediterranean Hortofruticulture La Mayora - CSIC - UMA. Avda. Dr. Wienberg s/n., Algarrobo-Costa, Málaga, 29750, Spain.
Integr Comp Biol. 2023 Dec 29;63(6):1352-1363. doi: 10.1093/icb/icad078.
Albuminous seeds, dispersed with a minimally developed embryo surrounded by nutrient storage tissue, are pervasive across extinct and extant early diverging angiosperm lineages. Typically, seed ontogenic studies have focused on the time between fertilization and seed release, but in albuminous seeds, embryogenesis is incomplete at the time of seed dispersal. Here, I studied the morphological and nutritional relationships between the embryo and the endosperm after seed dispersal in Illicium parviflorum (Austrobaileyales). Seeds of I. parviflorum germinate over a period of three months. Different stages during the germination process were anatomically evaluated using a combination of histochemistry and immunocytochemistry. At dispersal, the seeds of Illicium contain a tiny achlorophyllous embryo with minimal histological differentiation, surrounded by copious amounts of lipo-protein globules stored in the endosperm within cell walls rich in un-esterified pectins. Six weeks later, the embryo expanded and differentiated the vascular tissues before the emergence of the radicle through the seed coat, as the stored lipids and proteins coalesced within cells. Six weeks later, the cotyledons contained starch and complex lipids intracellularly, and accumulated low-esterified pectins in their cell walls. The proteolipid-rich albuminous seeds of Illicium exemplify how woody angiosperms of the Austrobaileyales, Amborellales, and many magnoliids release seeds with high-energy storage compounds that are reprocessed by embryos that complete development during germination. Seedlings of these lineages thrive in the understory of tropical environments, which match with the predicted habitats where angiosperms evolved.
富含蛋白质的种子，其胚胎发育不完全，周围环绕着营养储存组织，广泛存在于已灭绝和现存的早期分化的被子植物谱系中。通常，种子发生研究的重点是受精后到种子释放之间的时间，但在富含蛋白质的种子中，胚胎发生在种子散布时并未完成。在这里，我研究了八角属（八角目）中种子散布后胚胎与胚乳之间的形态和营养关系。八角属种子的萌发期为三个月。通过组织化学和免疫细胞化学相结合的方法，对萌发过程的不同阶段进行了解剖学评估。在散布时，八角属种子含有一个微小的无叶绿素胚胎，其组织分化程度很低，周围是大量储存在胚乳中的脂蛋白小球，这些脂蛋白小球储存在富含未酯化果胶的细胞壁内。六周后，胚胎在种皮中胚根穿出之前扩大并分化出维管组织，同时储存的脂质和蛋白质在细胞内聚集。六周后，子叶细胞内含有淀粉和复杂脂质，细胞壁中积累了低酯化果胶。富含蛋白的八角属种子是木质被子植物八角目、Amborellales 和许多木兰类植物的典型代表，它们释放出富含能量的储存化合物的种子，这些种子被在萌发过程中完成发育的胚胎重新加工。这些谱系的幼苗在热带环境的林下茁壮成长，这与被子植物进化的预测栖息地相匹配。
