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Amylases synthesis in scutellum and aleurone layer of maize seeds

1998; Elsevier BV; Volume: 49; Issue: 3 Linguagem: Inglês

10.1016/s0031-9422(97)00964-3

1873-3700

Kolli V. Subbarao, Rupali Datta, Rameshwar Sharma,

Botanical Research and Applications

Amylases were purified from maize endosperm and antibodies were raised. Immunochemical analysis showed that amylases were secreted into the endosperm from the surrounding scutellum and the aleurone layer. The synthesis was first initiated in the scutellum and was followed by the aleurone layer. The study shows that during the early germination period, amylase secreted from the scutellum mobilizes starch. The endosperm of germinating maize seeds contains four isozymes of α-amylases (α-amylase-1 to -4) and one isozyme of β-amylase. The α-amylases were purified by affinity chromatography on amylose and separated by DEAE-cellulose chromatography, into two groups, namely α-amylases-1,2 and α-amylases-3,4; and β-amylase was purified by precipitation as a glycogen-enzyme complex. The molecular weight of α-amylases-1 and -2 was 46 kD, α-amylases-3 was 44.5 kD and of α-amylases-4 was 47.5 kD. The molecular weight of β-amylase was 56 kD. During seed germination increase in amylolytic activity in endosperm was mainly contributed by secretion of α-amylases from adjoining aleurone layer and scutellum. The synthesis and secretion of α-amylases was first initiated in the scutellum followed by aleurone layers. Exogenous Ca2+ stimulated synthesis of α-amylases in both eleurone layer and scutellum. In contrast, though scutellum and aleurone layer synthesized β-amylase but it was not secreted to the medium. These results suggest that during the early germination period, α-amylases secreted from scutellum mobilizes starch.