About the Cover
The cereal aleurone cells, which form the outermost layers of the endosperm, are an excellent system for exploring the molecular actions of GA and ABA. In these terminally differentiated cells, GA upregulates the expression of hydrolytic enzymes to mobilize nutrients stored in the endosperm, and ABA antagonizes GA action. In addition, ABA upregulates genes involved in the establishment of stress tolerance. Hormone-responsive reporter constructs as well as effector constructs encoding various regulator molecules can easily be introduced into the aleurone cells via the biolistic particle bombardment technique. In this issue, Casaretto and Ho (pages 271-284), and in a previous issue Zentella et al. (Plant Cell 14: 2289-2301), have investigated the hormone signaling pathways by both constitutive expression and RNAi knock-down of signaling molecules. On the cover, a barley spike with developing seeds is shown next to an embryoless endosperm half-seed with the exposed aleurone layers stained for ß-glucuronidase activities used as a reporter enzyme in hormone signaling studies.
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Copyright © 2008 by the American Society of Plant Biologists
