Intact plant ethylene

This chapter is intended to provide an overview of the functions of the five major plant growth hormones in the intact plant auxin (lAA), gibberellins (GA), cytokinins (K), ethylene, and abscisic acid (ABA). The effects of these hormones have been described in detail on numerous occasions over the last 10 years (see general references at the end of this chapter). This review utilizes these previous reviews as well as including a survey of the literature published between January 1977 and January 1980. The most recent and surely the most detailed treatment of the subject is to be found in Phytohormones and Related Compounds A Comprehensive Treatise. D.S. Letham et al., Volumes 1 and 2, 1978. The intent of the present review is to provide a more general overview and to consider overall patterns of regulatory controls by hormones in the whole plant. 

The final step in the biosynthesis of ethylene is catalyzed by ACC oxidase. Application of ACC to most plant tissues results in a marked increase in ethylene production, indicating that ACC oxidase in these tissues is constitutive and not rate-limiting. Although ACC-dependent ethylene production is readily demonstrated in intact tissues, in vitro ACC oxidase activity has not been demonstrated independent of intact cellular material. Although intact protoplasts and vacuoles retained the characteristics of tissue ACC oxidase activity [9], Porter and John [24] reported that their preparations retained less than 5% of the activity associated with the parent tissue. They proposed that full ACC oxidase activity requires tissue integrity in addition to the previously noted cell membrane integrity. 

Rappaport L (1979) Does GA3 regulate cell division Plant Physiol 63 Suppl, p 32 Rauser WE, Horton RF (1975) Rapid effects of indoleacetic acid and ethylene on the growth of intact pea roots. Plant Physiol 55 443-447 Rehm MM, Cline MG (1973) Rapid growth inhibition of Avena coleoptile segments by abscisic acid. Plant Physiol 51 93-96... 

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