Intact plant gibberellin

In the belief that the failure of the stem section to grow meant that some essential cofactor must normally be supplied to the stem section by the rest of the plant, we began investigating the effect of plant extracts. A mixture of glycerides isolated from the pea nearly doubled the growth response of the section to auxin and gibberellin, even when applied at the extremely low concentration of 10 mg. per liter (3). Even so, the growth attained by the section is still less than that of the intact plant, and a cofactor other than those discussed in this paper may be involved. 

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. 

Even with gibberellin and auxin the growth of the defoliated or decapitated plants is significantly less than that of the intact ones, suggesting that, as with Gerbera, still other growth factors must be accounted for. In two other cases dual roles of auxin and gibberellin in mitosis are clearly indicated. 

Altman A, Mozes R (1977) Comparative basipetal transport of 6-benzylaminopurine-8-gibberellin A3- H, IAA-2- " C, and sucrose- " C in the root of intact Citrus auran-tium seedlings. Physiol Plant 39 233-235... 

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