Plant Growth Regulators in Plant Tissue Culture and Development

Abstract

Plant growth and developmental processes, such as germination, stem elongation, leaf growth and development, flowering, fruit set, and fruit growth and ripening, are controlled by plant growth regulators (PGRs), commonly but incorrectly called “plant hormones.” For general review of these processes, see recent plant biology textbooks (Mauseth, 1991; Raven et al., 1992; Salisbury and Ross, 1992; Taiz and Zeiger, 2002); more focused reviews of PGRs are contained in Davies (1995) and Arteca (1996). The interesting stories of PGR discovery are covered in these textbooks and here in Chapter 2. Study of PGR function can be complex because several PGRs typically work in concert with each other and their concentrations in the plant change with time, season, and developmental stage. Some PGRs are synthesized locally by cells for their own consumption, whereas others are synthesized in one organ and transported to other parts of the plant for a specific action, in which case their activity might be thought of as being similar to a plant “hormone.” Those produced by the plant are referred to as endogenous PGRs. However, as described in this chapter, natural and synthetic versions of many PGRs have been identified and commonly are supplied to intact plants and tissue cultures; these are termed exogenous PGRs. 1614_C08.fm Page 87 Friday, June 18, 2004 10:18 AM