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Studies on Localization of Food Reserves and Amylases in Maize Kernel
|Publication Year :||1998|
|Abstract:||本論文以台農351玉米為材料，利用高碘-希佛染劑(periodate Schiff's reagent)染多醣類，考馬斯藍(coomassie blue)染蛋白質，蘇丹黑(sudan black)染脂質，以探討玉米穀粒在發育與萌發期間，其澱粉、蛋白質和油脂等儲藏性物質的分佈。結果顯示在穀粒發育初期，果皮中有較多的多醣類和蛋白質；胚乳出現後，果皮中的多醣類和蛋白質逐漸減少，而胚乳中的多醣類和蛋白質則增加。在萌發後的穀粒中，胚乳內的多醣類，隨著萌發天數的增加而逐漸減少；且主要存在於胚軸及內子葉(scutellum)中的脂質，和存在於內子葉及糊粉層內的蛋白質，亦均隨著萌發天數的增加而逐漸減少。|
To study the distribution of food reserves in the developing and germinating maize kernels, periodate Schiff's reagent, Coomassie blue reagent and Sudan black solution were used for staining polysaccharides, proteins and lipids, respectively. During the early stages of kernel development, the polysaccharides and proteins were condensed in the pericarp tissue. Upon fertilization, the content of polysaccharides and proteins in the pericarp tissue declined, and in turn that in the endosperm tissue increased. After imbibition, the lipid in embryo, polysaccharide in endosperm and proteins in scutellum and endosperm were degraded during the post-germination period.
By using immunocytochemical method with antibodies against α- and β-amylases, the location of amylolytic enzymes inside kernels was investigated. In the developing kernel, β-amylase was exclusively localized in the pericarp tissue, especially in the outer layer part. And its location was shifted from the crown to the basal portion of the developing pericarp while the development of kernel was progressing. In the Day-1 germinating kernel, α-amylase was first localized at the scutellar epithelium, and then in the adjacent endosperm and the aleurone layer in the later germinating stages. Otherwise, β-amylase was exclusively expressed at the aleurone cells, but not in the starchy endosperm or scutellum. The result of immuno-gold labeling showed that β-amylase protein was distributed among the cytoplasm of aleurone cells in the Day-7 germinating kernel. These results suggested that β-amylase is not a secretory protein. Based on the degradative model of starch reserves and the distribution of amylolytic enzymes inside the starchy endosperm, it is concluded that the scutellum does play the most important role in food mobilization during the post-germination growth.
|Appears in Collections:||植物科學研究所|
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