Structural Changes of Chloroplasts in Green Cotyledons before and after Germination of Black Bean Seeds

黑豆種子形成時及發芽後其綠色子葉內葉綠體構造變化

呂良穗(L. S. Lu) ； 楊棋明(C. M. Yang) ； 陳榮銳(Y. R. Chen)

《國立臺灣博物館學刊》 60卷1期 (2007/03) Pp. 1-17

摘要

綠色子葉兩大主要功能是儲藏養分及行初期而短暫光合作用，以利幼苗發育。黑豆（Glycine max (L.) Merrilx cv Tainan 5）子葉在種子形成及發芽前後都綠色，且宿存而伸出地面。超微構造研究顯示種子發芽前後，其內含葉綠體發生了分解及重組現象。發育種子中，子葉內葉肉細胞葉綠體構造變化相當明顯，其中包括：澱粉粒形狀、數目及聚集；蛋白體、油體的聚集與消失；和類囊膜完整性及其層數、類囊腔寬度與長度等改變，這些結構性改變都與種子脫水現象有關，顯示脫水造成葉綠體漸趨瓦解，且脫水數速度快至葉綠素沒有完全消失，於是子葉顯出淡綠色。種子浸水發芽後，向光面葉肉細胞中液胞內蛋白體逐漸消失、細胞質內油體減少及色素體及粒線體數目增加，色素體轉變為長紡錘形葉綠體時，其內油滴減少及原類囊體長出單層類囊膜。完整葉綠餅出現於十日齡幼苗子葉，二十日齡幼苗已有老化葉綠體出現子葉中葉肉細胞。

關鍵字

黑豆 ； 葉綠體 ； 綠色子葉

並列摘要

Nutrient preservation and short-lived photosynthesis for seedling development are dual functions of green cotyledons. The epigeal chloroembryophytic cotyledons of black bean (Glycine max (L.) Merrilx cv Tainan 5) were examined with electron microscopy. The disorganization and reorganization of chloroplasts were observed in green cotyledons of maturing and germinating black bean seeds. In developing seeds, structural changes in mesophyllous chloroplasts of cotyledons are consipicuous. These include starch-grain changes in shape and aggregated form, an accumulation of protein bodies, oil bodies and plastoglobuli, the rigidity and stacking of the thylakoid membrane, and membrane intactness. All of the structural changes are related to seed desiccation. After seed germination, a gradual disappearance of protein bodies in vacuoles, and a decrease in number of oil droplets in cytoplasm, and a multiplication of plastids and mitochondria in mesophyllous cells of adaxial sides of cotyledons were observed. The distinct changes in their chloroplasts are characterized by decreasing numbers of plastoglobuli, and the formation of prolamellar bodies from which the active thylakoid membrane in two to three layers extends to both ends of spindle-like chloroplast. Chloroplast in long-spindle shape and regular thylakoid stacking appear in the cotyledonal mesophyll of 10-day-old seedlings. Senescent chloroplasts were found in mesophyll of wilting cotyledons of 20-day-old seedlings.

並列關鍵字

Black bean ； Chloroplast ； Green cotyledon ； Disorganization ； Reorganization ； Seed maturation ； Seed germination