The calcium-dependent protein kinase HvCDPK1 mediates the gibberellic acid response of the barley aleurone through regulation of vacuolar function.

In the aleurone cells of the cereal grain, gibberellic acid (GA) induces the secretion of hydrolases that mobilize endosperm reserves to fuel early seedling growth. GA is known to trigger a range of cellular responses, including increases in cytoplasmic calcium, vacuolar reserve mobilization, gene transcription, and the synthesis and secretion of hydrolases. To further define elements of the Ca2+-dependent GA response machinery, we have cloned a Ca2+-dependent protein kinase (HvCDPK1) from these cells.

From common signalling components to cell specific responses: insights from the cereal aleurone.

Studies into the molecules underlying plant signal transduction events continue to reveal the involvement of highly conserved factors such as Ca2+, calmodulin, cyclic GMP and phospholipases in a remarkably diverse array of physiological processes. The hormonal response systems in the aleurone cells of the cereal grain and in the stomatal guard cell are beginning to reveal how diversity of response can be hard wired into these cells despite the use of these common signalling intermediates. In both the aleurone and the guard cell ABA signalling operates through the action of phospholipase D and alterations in a Ca2+-dependent signalling system.