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The interaction of trans-cinnamic acid with the cytochrome P-450 of microsomes derived from washed potato slices has been studied. The washing process increased the specific content of microsomal electron transport components and hence provided a useful material in which to study the interaction. Evidence is presented that the trans-cinnamic acid interacts with the cytochrome P-450, and that this interaction is analogous to ‘type I’ interactions of other cytochrome P-450 systems. This evidence includes the formation of a ‘type I’ substrate binding spectrum, an increased rate of reduction of cytochrome P-450 by NADPH in the presence of trans-cinnamic acid, an increased oxygen uptake and NADPH oxidation when trans-cinnamic acid is added to the microsomes in the presence of NADPH, and a close correlation between biophysical parameters of electron transport in the cytochrome P-450 system and enzymological parameters of the trans-cinnamic acid 4-hydroxylation reaction. The investigation has been extended to cytochrome P-450 systems of other tissues and it has been found that the trans-cinnamic acid 4-hydroxylation reaction cannot account for the presence of most of the cytochrome P-450 in several tissues. This suggests that other functions of higher plant cytochrome P-450 chains exist, and that the substrate specificity of the hemoprotein may vary in different plant tissues.

l -Phenylalanine ammonia-lyase (EC 4.31.5) undergoes a transient increase in activity in illuminated discs of Solanum tuberosum tuber parenchyme. Cycloheximide and cordycepin inhibit the initial increase in enzyme activity, but if addition of these anti-metabolites is delayed until the time of maximum enzyme levels, the subsequent decline in enzyme activity is inhibited (Lamb, C.J. (1977) Planta, 135, 169–175). The effect of delayed treatment with cycloheximide or cordycepin on the turnover of phenylalanine ammonia-lyase has been analysed by density labelling with 2H from 2H2O. Delayed introduction of cycloheximide or cordycepin reduces the rate of labelling of phenylalanine ammonia-lyase whilst preventing the decay in enzyme activity observed in controls not treated with inhibitor, and this labelling pattern cannot be accounted for by effects of cycloheximide or cordecypin on the labelling of amino acid pools. It is concluded that delayed treatment with cycloheximide or cordycepin leads to the maintenance of high levels of phenylalanine ammonia-lyase by inhibition of the removal of active enzyme rather than by maintenance of high rates of enzyme synthesis.

1. (1) The regulation of the accumulation of the isoflavonoid-derived phytoalexin phaseollin in cell suspension cultures of Dwarf French Bean (Phaseolus vulgaris) has been investigated. 2. (2) An elicitor preparation from cell walls of Colletotrichum lindemuthianum, the causal agent of anthracnose disease of French bean, caused a marked accumulation of phaseollin in the cultures. The elicitor induced phaseollin accumulation to a level of 60% that obtained with the artificial elicitor autoclaved ribonoclease A and was maximally active at a concentration (weight basis) of at least 50 times lower than required for maximall response to ribonuclease. 3. (3) Elicitor preparations from cell walls of Phytophthora megasperma var. sojae, a fungal pathogen of soybean, and Botrytis cinerea, the common grey mould, were much less effective than the C. lindemuthianum wall-released elicitor. 4. (4) There was a marked but transient increase in the extractable activity of phenylalanine ammonia-lyase, the enzyme catalysing the first reaction in the biosynthesis of phaseollin from l -phenylalanine, in response to the elicitor from C. lindemuthianum. 5. (5) Comparative density labelling with 2H from 2H2O indicated that the elicitor stimulates de novo synthesis of phenylalanine ammonia-lyase, and that this is an early event in the phytoalexin defence response. 6. (6) These findings provide the basis of a scheme for elicitor induction of phytoalexin accumulation.

This chapter deals with recent studies on the biochemistry of disease resistance expression in Phaseolus vulgaris L., paying particular attention to the regulation of phytoalexin accumulation. Advantages of this system for biochemical studies are: (a) The disease resistance profile of P vulgaris has been characterised genetically to some extent (Meiners, 1981) and physiologically (Bailey, 1981). In particular, different cultivars (eg. Kievit, Immuna, Red Kidney) undergo highly specific interactions with physiological races of Colletotrichum lindemuthianum (eg. β,δ,γ) the causal agent of anthracnose disease of P. vulgaris. (b) The physiology of this interaction has been extensively studied using hypocotyls, the organ which together with leaves is the natural site of attack by C. lindemuthianum. There is strong evidence that the differential accumulation of the isoflavonoid derivative phaseollin and other structurally related phytoalexins such as phaseollidin, phaseollinisoflavan and kievitone in resistant and susceptible interactions plays a crucial role in the specificity of host resistance (Bailey, 1981). (c) Detailed study of the effects of phytoalexin inducing agents on phenylpropanoid metabolism in P. vulgaris hypocotyls indicates that accumulation of phytoalexins is a specific event, and the levels of most other phenylpropanoid products (eg. hydroxycinnamic acids) remain roughly constant relative to untreated control tissue (Rathmell and Bendall, 1971).

With the demand for mental health services in Australia continuing to grow, it is imperative that tertiary trained counsellors continue to enter the profession; yet little is known about the factors that contribute to a successful entry. This qualitative, phenomenological study investigated the transition from postgraduate counselling student to working counsellor by exploring the lived experience of those who have made this transition within the last five years. By focusing on the transitional experience itself, the study aimed to provide useful information for stakeholders holding key roles in such transitions—specifically students, academic institutions, professional bodies, and employers of counsellors within Australia. While results suggest that many factors affected the transitional experience, students’ practicum placement played a disproportionately large role in determining their early career path. Other important factors included the background of the individual, their experiences while studying, and the professional support in place once they had started working. This study also identified that students’ expectations of what it might be like to work as a counsellor in private practice were not always aligned with lived experience. It is hoped that knowledge about what has been valuable to recently transitioned early career counsellors will be of ongoing benefit to all stakeholders.