The Induction of Phenylalanine Ammonia Lyase and Phaseollin by 9-Aminoacridine and Other Deoxyribonucleic Acid Intercalating Compounds

Abstract

Bean pod tissue (Phaseolus vulgaris L. var. Top Crop) is induced to produce phaseollin when challenged with various microorganisms. The pods react in the same manner when challenged with 9-aminoacridine. This compound also caused an increase in concentrations of phenylalanine ammonia lyase, an enzyme of the phaseollin synthesizing pathway. Both the synthesis of phenylalanine ammonia lyase and phaseollin are subject to inhibition by actinomycin D, cycloheximide, or 6-methylpurine. The results suggest that both phaseollin production and increased phenylalanine ammonia lyase, when induced by 9-aminoacridine, require newly synthesized RNA and protein.The concentration of 9-aminoacridine optimal for synthesis of phaseollin and PAL (0.5 mg/ml) does not increase the rate of total protein synthesis. However, there is a differential effect of 9-aminoacridine on synthesis of certain protein fractions.Optimal concentrations of 9-aminoacridine induce phaseollin and phenylalanine ammonia lyase synthesis while reducing the net synthesis of RNA during the period of induction.The planar three-ring structure of 9-aminoacridine appears to be a desirable feature for phaseollin and phenylalanine ammonia lyase induction. Similar compounds, all DNA intercalators, having dimethylamino, diethylamino, amino, or 9-alkylamino substitutions of a three-ring acridine skeleton, are also inducers of phenylalanine ammonia lyase and phaseollin synthesis. It is suggested that 9-aminoacridine and other DNA intercalators function as inducers of phaseollin and phenylalanine ammonia lyase synthesis by reacting with the DNA template.Bean pod tissue produces phaseollin, an isoflavonoid with antifungal properties, when challenged by various microorganisms or treated with a wide variety of chemicals (5,7,9,12,18). Phaseollin is not detectable in untreated tissue (11). The induced production of phaseollin in infected bean tissue provides a level of defense against certain fungal pathogens (6, 18). The mechanism of its induction is of interest in understanding disease resistance responses in plants. ' This paper reports that 9-aminoacridine, and a number of other similar compounds, can induce the formation of phaseollin and/or phenylalanine ammonia lyase (PAL)3, E.C. 4.3.1.5 (a key enzyme in the biosynthesis of phaseollin [11]) in excised bean pods. Changes in RNA and protein synthesis which occur subsequent to the application of 9-aminoacridine are also described. MATERIALS AND METHODS Plant Materials. Bean plants (Phaseolus vulgaris L. var.Top Crop) were grown in sand. Fresh pods, 3 to 5 cm in length, were excised and split lengthwise in three 1 to 2 mm slices, spread evenly over the bottom of a Petri dish, and then treated as described below.Phenylalanine Ammonia Lyase. After designated incubation periods in the dark, 1-g samples of pods were homogenized and assayed for PAL. The assay mixture contained 1.8 ml of homogenate, 0.2 ml of borate buffer, pH 8.8, 20 ,umoles of L-phenylalanine, and 0.125 btC of L-phenylalanine-U-14C(265 mc/mmole). The r...

Phytoalexins: Enzymology and Molecular Biology

“…An increase in the overall rate of RNA synthesis occurs in a number of systems following infection (696,697,(704)(705)(706), and inhibitors of RNA synthesis have been observed t o inhibit necrogenic resistance (693,696), phytoalexin accumulation (102,104,106,108,660,661,693,694), and induction of appropriate biosynthetic enzymes (102,1O4,108,660,66 1). However, the interpretation of such observations is limited and qualified by the same kinds of considerations as those outlined above appertaining to inhibitors of protein synthesis.…”

“…In principle, the simplest way to demonstrate the involvement of de novo protein synthesis is by application of inlubitors such as cycloheximide, chloramphenicol, puromycin, or blasticidin S. Phytoalexin accurnulation in response to infection (484,693) and treatment with biotic (694) and abiotic (102,106,660,661) elicitors is sensitive to inhibitors of protein synthesis. Necrogenic resistance can be destroyed by such inhibitors (484,693,(695)(696)(697)(698), and in a number of cases, but not all (695), this correlates with inhibition of phytoalexin accumulation (484,693).…”

DNA Damage and Chromatin Conformation Changes Confer Nonhost Resistance: A Hypothesis Based on Effects of Anti-cancer Agents on Plant Defense Responses

“… History of studies regarding anti-cancer and other compounds on DNA damage in plants. The figure were created based on the following references (chronological order): Schwochau and Hadwiger, 1968 , 1969 ; Hadwiger and Schwochau, 1970 , 1971 ; Hadwiger and Martin, 1971 ; Hess and Hadwiger, 1971 ; Hadwiger, 1972a , b ; Hadwiger et al, 1976 , 1977 , 1995 ; Sander and Hadwiger, 1979 ; Hadwiger and Beckman, 1980 ; Walker-Simmons et al, 1983 ; Kendra et al, 1989 ; Parsons and Hadwiger, 1998 ; Choi et al, 2001 ; Klosterman et al, 2003 ; Hartney et al, 2007 ; Hadwiger and Tanaka, 2015 ; Hadwiger and Tanaka, 2017b ; Tanaka and Hadwiger, 2017 . …”

Carbohydrates, Proteins, Cell Surfaces, and the Biochemistry of Pathogenesis

“…These include treatment of the plant tissues with ultravio let light (19,51) and freezing (101). Phytoalexin synthesis is stimulated, too, by the application to plant tissues of many chemicals such as polyamines (48,49), antibiot ics (II, 114, 115), DNA intercalating agents (50,55), and salts of heavy metals (26,104,114). However, the concentrations of these reagents required to stimulate phytoalexin synthesis (10-3 to 10-5 M) are higher than those (10-8 to 10-10 M) required of the pathogen-produced elicitors.…”