Increases in phenylalanine ammonia lyase activity and pisatin synthesis were induced in excised pea pods (a) by basic polypeptides such as protamine, histone, lysozyme, cytochrome c, and ribonuclease; (b) by the polyamines spermine, spermidine, cadaverine, and putrescine, and (c) by the synthetic oligopeptides poly-L-lysine, poly-DL-ornithine, and poly-Poly-L-lysine (1 milligram per milliliter, molecular weight 7,200) was utilized as a model inducer of pisatin and phenylalanine ammonia lyase. The poly-L-lysine-induced responses could be inhibited by adding the RNA synthesis inhibitors cordycepin or a-amanitin to the pods prior to or at the time of inducer application. Cordycepin added 1.5 hours after inducer no longer completely inhibited induction. The application of poly-L-lysine was shown to characteristically change the rate of RNA synthesis within 30 minutes. Ultrastructural changes in pea nuclei were detected within 3 hours, and gross changes in nuclear morphology were apparent at 14 hours after inducer application. The physical appearance of uranyl acetate-stained chromatin isolated from poly-L-lysine 2 hours after inducer application differed from that of water-treated tissues. The template properties of chromatin extracted from pods 3 hours after inducer application were consistently superior to control chromatin when assayed with Escherichia coli RNA polymerase (without sigma factor). Chromatin from poly-L-lysine-induced tissue also bound 49% more actinomycin D-'H.The DNA-complexing properties of inducer compounds and the induced changes in the template and dye-binding properties of pea chromatin formed the basis for a proposed mode of action for phytoalexin induction.The functions of numerous polypeptide hormones (5) have been characterized in animal systems; however, interest in the potential role of polypeptides in regulating plant processes is still limited. There is reason to believe that numerous polypeptide components remain to be discovered which can influence plant cell processes (46). Phytoalexin induction in pea tissue has been employed as one measure of the effects of chemically defined compounds on the regulation of cell processes (12,(15)(16)(17)(18)(19)(20)(21)38). We now report that basic peptides can induce gene-controlled responses, and we demonstrate that this gene-activating potential exists for basic compounds (2, 41, 47) which occur in plants and other higher organisms.The synthetic compound, poly-L-lysine, was chosen as a model inducer because of its amino acid residue uniformity and chemical simplicity. This paper examines the phytoalexininducing effect of poly-L-lysine in relation to (a) alteration of the fine structure of nuclei and cell membranes, (b) template activity and dye-binding capacity of isolated chromatin, (c) the in vivo rate of RNA synthesis, and (d) the dependency of the induction process on RNA and protein synthesis.Our previous hypothesis (20, 38) that regulation of gene expression can occur as a result of changes in the conformation of specific segment...

Excised pea pods responded similarly to both the invasion of plant pathogenic fungi and the presence of bean tissue, bean pollen, and mouse tumor cells by synthesizing pisatin and by developing a characteristic yellow-green fluorescence. Both responses were dependent on RNA and protein synthesis. Conversely, the foreign pollen and incompatible fungi were sensitive to the pea pod tissue and were subject to abnormal development.The induction of pisatin and the yellow-green fluorescence development were mediated by multiple compounds of varying sizes released by fungi or mouse tumor cells. The incompatibility between a bean pathogen, Fusarium solani f. sp. phaseoli, and pea pod tissue was hypothesized to occur as a result of the cross contamination of such inducing compounds.mains whether pisatin alone is the factor determining disease resistance in the pea plant.In our studies with peas, we found that the induction of pisatin is associated with gross changes in the rate of synthesis of numerous cellular proteins (2,6,8). These results indicate that disease resistance may also be a more comprehensive response to compounds released by plant pathogenic fungi or other cells foreign to peas. Here, we demonstrate some similarities between the disease resistance responses induced in pea tissue by plant pathogenic organisms and cellular incompatibility responses which occur when the pea tissue is in contact with various nonparasitic cells. MATERIALS AND METHODS SOURCES AND CULTURES OF TISSUES FOR INCOMPATIBILITY STUDIESThe physiological relationship between the plant and a pathogenic organism which can successfully infect it is unique (.14). Only a few plant pathogenic fungi can successfully parasitize a given plant genotype. The coexistence between many other combinations of plants and plant pathogens which occur in nature is usually brief. This limited coexistence is closely correlated with the initiation of certain physiological responses. Phytoalexins are often designated as determinants in the plant's disease resistance response (4, 9). Disease resistance has also been associated with cellular discoloration (10-12).In pea pod tissue inoculated with various plant pathogenic fungi, pisatin eventually accumulates in levels which have been shown to be inhibitory to both the germination and linear growth of certain fungal spores in artificial culture (3). However, fungi pathogenic to peas induce pisatin production nearly as quickly as closely related fungi which are nonpathogenic on peas (2). It is sometimes difficult to distinguish clones of the fungus pathogenic on peas from those nonpathogenic on peas, either on the basis of sensitivity to pisatin or on the potential to degrade accumulated pisatin (2). Thus, doubt re- Tissue pieces were applied to the pods as discs. After treatment, the Petri plates were incubated in a humid plastic bag at 22 C.Plant Pathogenic Fungi. Two strains of Fusariumit solani, f. sp. pisi (a pea pathogen) and f. sp. phaseoli (a bean pathogen), were used to promote "compatibility" and "i...

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Horticulture businesses will be encouraged to hire qualified individuals with disabilities due to the enactment of the Americans with Disabilities Act of 1990. Maintaining a safe workplace is a considerable challenge due to the use and storage of restricted-use pesticides. In a vocational training program, two persons with mental disabilities were trained to be effective Integrated Pest Management scouts using systematic teaching procedures. Trainees acquired employable skills while providing a service that enabled management to reduce use of conventional pesticides on a greenhouse poinsettia crop by up to 65%.