About the Cover
Cells in maize endosperm undergo multiple cycles of endoreduplication.
Although the role of endoreduplication is unclear, it is thought to provide a mechanism that increases cell
size and enhances gene expression. Leiva-Neto et al. (pages 1854-1869)
investigated this process by expression of a gene encoding a dominant
negative mutant form of cyclin-dependent kinase A, which reduced
endoreduplication in transgenic maize endosperm. Expression of
the defective enzyme lowered kinase activity and reduced total DNA content of endosperm nuclei. However,
reduced endoreduplication did not significantly affect cell size or level of
endosperm gene expression and only slightly reduced starch and
storage protein accumulation, suggesting that endoreduplication might
not enhance transcription of genes associated with starch and storage
protein synthesis. The cover image shows a starchy endosperm cell with
an enlarged endoreduplicated nucleus, starch granules (irregular light spheres), and protein bodies (small,
dark-stained spheres). Image by Giovana Augusta Torres and Joao Torres Leiva-Neto.
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Copyright © 2007 by the American Society of Plant Biologists
