A (1 to 3)-β-glucanase expressed during oat endosperm development
2004
Martin, D.J. | Somers, D.A.
In mature kernels of oat (Avena sativa L.) and other cereals, mixed-linked (1 leads to 3; 1 leads to 4)-beta-glucans and arabinoxylans are major structural polysaccharides in cell walls of the endosperm. However, (1 leads to 3)-beta-glucans are deposited transiently in walls during cellularization of endosperm early in grain development [Planta 202 (1997) 414-426]. The absence of (1 leads to 3)-beta-glucans in mature endosperm cell walls suggests that (1 leads to 3)-beta-glucanases are active during endosperm development. To investigate the role of beta-glucanases during endosperm development, a (1 leads to 3)-beta-glucanase cDNA, Oglc13, was isolated from an oat (A. sativa L.) kernel cDNA library. The enzymatic activity of the protein product, OGLC13, expressed from the cDNA in an in vitro expression system, exhibited substrate specificity for (1 leads to 3)-beta-glucans. Oglc13 transcripts were detected in the endosperm of portions of developing kernels with the highest steady state level of mRNA at 15 days after anthesis (DAA) and not in vegetative tissues. Antibodies raised against OGLC13 immunoprecipitated (1 leads to 3)-beta-glucanase activity from endosperm extracts of 10 and 15 DAA kernels and milky endosperm extracted from 15 DAA kernels. The OGLC13 antibodies did not precipitate (1 leads to 3)-beta-glucanase activity from leaf extracts. These results indicated that Oglc13 is a unique (1 leads to 3)-beta-glucanase expressed early in endosperm development.
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