Analysis of Hormonal Controls

The complexity of the controls of specific processes by several hormones probably has been an important factor in the slow progress in the understanding of regulatory controls. 

There is no doubt that subcellular compartmentation of hormones exists. Evidence for subcellular compartmentation of plant hormones is now being reported (e.g., de la Fuente and Leopold 1972, Loveys 1977, Ohlrogge et al. 1980). Water stress induces a large rise in extrachloroplastic ABA as opposed to that inside the chloroplasts (Loveys 1977, Walton 1980). Undoubtedly, more evidence for compartmentation will emerge as hormone target sites are analyzed. Compartmentation of hormones should be viewed as a possible complication in the analysis of hormones extractable or diffusible from tissues. 

Having explored some of the difficulties and limitations in the concept of hormone systems and the complications introduced by multiple hormonal controls, it seems particularly important to examine the experimental approaches to working out these systems. 

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One of the most unnecessary failings in hormone analysis has been a paucity of effort to correlate endogenous hormone levels with quantitative measures of development to establish a relationship or lack of one. Thus, an important aspect in the analysis of hormonal control carries some interpretative difficulties, yet the two approaches outlined plus bits and pieces of other types of evidence described below have given enough data to understand at least parts of some hormonal control systems. 

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