Variations in β‐aspartate kinase activity during the development of maize endosperm

Henke, Randolph R.; Wahnbaeck-Spencer, Rosemarie

doi:10.1016/0014-5793(79)80261-6

Cited by 8 publications

(2 citation statements)

References 24 publications

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“…The highest level of AK activity was observed at 16 DAP, falling to nearly zero at 28 DAP. The result is similar to those of previous studies (Henke and Wahnbaeck-Spencer, 1979;Brennecke et al, 1996), in which a higher rate of metabolism was observed ∼15-25 DAP, followed by a continuous reduction of the rate of metabolic activity. At the 15-25 DAP stage, amino acids are being synthesized to be used in storage protein synthesis.…”

Section: Resultssupporting

confidence: 92%

“…Enzymes such as AK and HSDH have been isolated and studied in several plant species (Azevedo et al, 1997). AK, which regulates the biosynthesis of lysine in plants, has been studied previously in maize tissues, including the endosperm (Henke and Wahnbaeck-Spencer, 1979;Brennecke et al, 1996). For HSDH, however, very little is known about its regulation in the maize endosperm.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Quality Protein Maize: A Biochemical Study of Enzymes Involved in Lysine Metabolism

Gaziola

Alessi

Guimarães

et al. 1999

J. Agric. Food Chem.

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Quality protein maize (QPM) varieties have been produced by the introduction of opaque-2 modifier genes. Two QPM varieties, BR451 and BR473, a wild type and an opaque-2 variety, have been used to study key enzymes controlling lysine metabolism in the endosperm during development. Aspartate kinase and homoserine dehydrogenase enzymes, which are involved in lysine and threonine biosynthesis, respectively, exhibited identical activity patterns during endosperm development, with a maximum specific activity at 16 days after pollination. The QPM varieties exhibited higher levels of aspartate kinase activity in the endosperm, suggesting an increased rate of lysine biosynthesis when compared to the opaque-2 and wild-type genotypes. Similar results were observed for the lysine ketoglutarate reductase and saccharopine dehydrogenase enzymes, which form a single bifunctional polypetide involved in endosperm lysine degradation. Both enzyme activities were strongly reduced in the opaque-2 maize variety when compared to the wild-type maize, whereas the QPM varieties exhibited even lower levels of lysine ketoglutarate reductase-saccharopine dehydrogenase activities when compared to the opaque-2 variety. The developmental pattern of enzyme activity showed a different profile when compared to the enzymes involved in lysine biosynthesis, with activity being detected only 12-16 days after pollination (DAP) and maximum activities approximately 24 DAP. These results also suggest that the modifier genes have intensified the effect of the opaque-2 mutation on lysine ketoglutarate reductase-saccharopine dehydrogenase. These alterations lead to an increase in soluble lysine in the endosperm of the QPM varieties when compared to the opaque-2 and wild type.

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Section: Resultssupporting

confidence: 92%