Intact plant hormonal

In ISR expressing Arabidopsis, it was shown that there are no local and systemic changes in the levels of JA and ET, although an intact response to both JA and ET is required [12,68]. This suggests that ISR is based on an enhanced sensitivity to these plant hormones rather than on an increase in their production. This is supported by ISR expressing plants which show a primed expression of the jasmonate responsive gene Atvsp [22] upon infection with P. syringae pv. tomato. 

The adventitious root cultures of Datura innoxia, Duboisia hybrid M-II-8-14 (a cross-bred between D. myoporoides and D. leichhardtii), and Scopolia tangutica were established from the axenic shoot cultures or intact plants (in the case of Duboisia) on MS solid medium containing 0.1 mg/1 NAA or 1.0 mg/1 lAA. The adventitious roots were maintained in MS liquid medium containing the same phytohormones (0.1 mg/1 NAA or 0.5 mg/1 lAA) in the dark. Addition of auxin in the culture medium has been employed for the maintenance of adventitious root cultures [14], however, the adventitious roots of H. albus and H. niger were induced and maintained in hormone-free 1/2 MS medium [15]. 

Lyophilized hairy roots, cultured in hormone-free B5 liquid medium for 4 weeks, were extracted as above and subjected to the combination of column chromatographies using Sephadex LH-20 and MCI-gel CHP-20P to afford six phenolics, 1, 2,8, 12, 13 and ellagic acid (16) (Fig. 4). These phenolics obtained from the hairy roots were also isolated from the leaves of the intact plant of G. thunbergii. 

Zilversmit et al. [21] used the original equation to look at the disappearance of a compound from the blood stream where the assumption of quick and efficient equilibration is likely to be valid. The situation is likely to be considerably more complex, however, where a plant hormone is supplied to an intact root or shoot. This paper sets out to examine the factors involved in equilibration of exogenous hormone with endogenous pools and to what extent lack of equilibration affects measurement of turnover rates. 

Although considerable data now implicate particular hormones in the control of senescence, data which demonstrate and integrate the specific hormonal control systems that function in intact plants are limited. A model for hormonal control of monocarpic senescence proposed by Woolhouse will not be considered here, because it is mostly incorrect and it is discussed elsewhere [19]. The hormonal regulation of leaf senescence as a component of monocarpic senescence in soybean is a case where we can begin to relate specific hormones to the correlative controls. At this time, the role of cytokinins (Section 2) and the nature of the senescence signal (Section 3) warrant special consideration. 

Various data indicate that phytohormones modulate protein phosphorylation in plant cell nuclei. For example, 2,4-D-pretreatment of soybean hypocotyls activated in vitro protein phosphorylation in isolated nuclei, and this was consistent with an in vivo increase of RNA synthesis [12]. Other phytohormones also alter nuclear protein phosphorylation in plants, and these include ABA [23], GA3 [25] and cytokinins [15]. However, in all these experiments phytohormones were applied to intact plants or to isolated plant organs. Therefore, the hormonal modulation of nuclear protein phosphorylation could be an indirect result of earlier cell response to the phytohormone. 

Much of our information on hormonal regulation has been from experiments in which hormone is applied to tissue segments. While these studies have been informative, they have made us aware of precautions necessary in applying results to functions of hormones in the intact plant. It has become clear that the effects of a particular hormone are dependent on other hormones, and that the applied hormone may trigger changes in the endogenous levels of other hormones. 

The evidence is overwhelming that the balance of endogenous hormones is affected by environmental parameters. It is, therefore, not surprising that the literature contains many apparently conflicting reports of the effects of applied hormones, especially when intact plants are used. The changes in hormone... 

The hormonal regulation of root elongation in the intact plant is poorly understood. This is partly because all the major plant hormones can inhibit root cell elongation at physiological concentrations. Since roots produce or at least contain each of these inhibitors , it seems clear that root elongation must... 

In spite of the uncertainties, difficulties, and complications mentioned so far and to be considered further below (see Sect. 3.3.3), the results obtained are generally believed to reflect and describe the properties of the hormone transport systems in intact plants. This belief is supported by results obtained with other methods which, at least partly, confirm the estimations derived from the intercept method. 

By use of these various techniques it has been shown, especially for auxins, that hormones applied to the unfolded leaves of intact plants are generally... 

Specificity of the Auxin Transport System. Comparative studies with chemically closely related compounds reveal a positive correlation between auxin activity and degree of basipetal polarity in the transport of these substances (e.g.. Went and White 1939, Leopold and Lam 1961, Jacobs 1967, Hertel etal. 1969, Veen 1972). Further, the basipetal transport of auxins is specifically inhibited by substances such as TIBA, naphthylphthalamic acid (NPA), 3,3a-dihydro-2-(p-methoxyphenyl)-8H-pyrazolo[5,la] isoindol-8-one (DPX 1840) (see Sect. 3.3.4.3) not only in treated sections but also when they are applied to intact plants at the loci of natural auxin production (see p 100). In summary, the numerous transport studies make certain the presence of a unique transport system, which is specific for auxin molecules, and which moves the hormone basipetally from the natural auxin sources in the shoot and then on to the root to regulate growth and other developmental processes. It is clear that this system is fully functional in tissue sections which is the material which has been used most in transport studies. 

Konings H (1968) Auxin in root geotropism. In Vardar Y (ed) The transport of plant hormones. North-Holland, Amsterdam, pp 237-250 Konings H (1969) The influence of acropetally transported indoleacetic acid on the geotropism of intact pea roots and its modification by 2,3,5-triiodobenzoic acid. Acta Bot Neerl 18 528-537... 

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. 

As yet the effects of hormones on the amount and transport of other hormones in the intact plant are not sufficiently understood to allow generalizations to be made. 

Although it is virtually impossible to do ideal experiments with intact plants, certain considerations should be kept in mind in all experiments. Manipulations of whole plants are at best disruptive. Specifically, cutting a plant or plant part will inevitably produce a wound response and in addition it will interrupt hormonal signals which would have been received in the intact plant. Replacing plant parts with variously applied hormones may lead to the presence of the hormones in unnatural places, and to unusual metabolism of these hormones both at the cut surface and within the plant. In addition exogeneously applied hormones may increase an endogenous pool to the point of producing hormone imbalance and metabolic disturbance. 

C12H20O4. M.p. 165°C. A plant growth hormone, which is produced in damaged plant tissue, and on diffusing into adjacent intact tissue cells stimulates them to divide. Traumatic acid has been isolated from the pods of green beans. 

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