Calcium Ions as Intracellular Second Messengers in Higher Plants

• Published in: Advances in Botanical Research Vol. 22; pp. 45 - 96
• Main Authors: Webb, Alex A.R., Mcainsh, Martin R., Taylor, Jane E., Hetherington, Alistair M.
• Format: Book Chapter Journal Article
• Language: English
• Published: United Kingdom Elsevier Science & Technology 1996
• Subjects: Botany & plant sciences; calcium; chemical constituents of plants; homeostasis; ion balance; ion transport; literature reviews; Plant pathology & diseases; plant physiology; quantitative analysis; regulation; stimuli
• ISBN: 0120059223; 9780120059225
• ISSN: 0065-2296; 2162-5948
• DOI: 10.1016/S0065-2296(08)60056-7

This chapter discusses calcium ions as intracellular second messengers in higher plants. Intracellular second messengers are used to couple extracellular stimuli, such as hormones to their characteristic intracellular responses. The interaction of the extracellular stimulus with its receptor sets in motion a train of events that results in an alteration in the concentration of another molecule in the cytosol. This alteration then triggers the cell's internal machinery to produce the response that is typical of the primary stimulus. As the field of stimulus–response coupling had its origins in mammalian physiology, where the primary stimulus is itself frequently secreted from an endocrine gland and is known as a first messenger, then it follows that the cytosolic molecules that link the first messenger with the final response should be called intracellular second messengers. The other possible sources of free calcium used to generate the calcium signal are the internal stores. Release of calcium from these sites is indirect and usually relies on the participation of other second messengers. Of these mechanisms, perhaps the best understood is the coupling process which proceeds through the operation of the phosphoinositide cycle. Central to the study of calcium ions as second messengers is the ability to measure accurately the concentration of free calcium ions in the cytosol of single cells and to detect changes that occur after the application of an appropriate stimulus.