Book Review: GENETICALLY ENGINEERED ORGANISMS: BENEFITS AND RISKS

In the continuing debate on the introduction into the environment of genetically modified organisms, particularly those modified by recombinant DNA, there are few books suitably written for policymakers, the lay public and scientists in other fields. This book describes the current state of the science and art of genetic engineering, potential uses (particularly outside the laboratory), and the benefits that can be expected. It is particularly pertinent for examining potential risk and management of risk from the perspective of the United Kingdom

THE PLANT PATHOGENIC CORYNEBACTERIA

The plant pathogenic corynebacteria are a fascinating group of bacteria that produce effects as diverse as any in the microbial world, ranging from wilts to abnormal growths. Several new pathogens have been discovered since this group was reviewed by Jensen (75), Starr (157), and Lelliott (96). Most subsequent reviews have dealt with taxonomy. The areas covered in this review necessarily reflect my biases and limitations. However, this review attempts to be comprehensive in some areas, and it calls attention to other areas that would benefit from more detailed investigation

Synthetic and Complex Media for the Rapid Detection of Fluorescence of Phytopathogenic Pseudomonads: Effect of the Carbon Source

Fluorescence is of diagnostic value for differentiating among species of aerobic pseudomonads (R. Y. Stanier, N. J. Palleroni, and M. Doudoroff, J. Gen. Microbiol. 43:159, 1966). The standard medium for detecting fluorescence is Medium B (E. 0. King, M. K. Ward, and D. E. Raney, J. Lab. Clin. Med. 44:301, 1954), which supports fluorescent pigment production of most pseudomonads tested (0. Jessen, Pseudomonas aeruginosa and other green fluorescent pseudomonads, A taxonomic study, Munksgaard, Copenhagen, 1965; R. Y. Stanier et al., J. Gen. Microbiol. 43:159, 1966). Minerals (J. V. King, J. J. R. Campbell, and B. A. Eagles, Can. J. Res. C 26:514, 1948), amino acids (J. De Ley, Ann. Rev. Microbiol. 18:17, 1964), and peptones (E. 0. King et al., J. Lab. Clin. Med. 44:301, 1954) affect fluorescence. The effect of carbon sources had not been shown. Although glycerol, glucose, or maltose can be used interchangeably in Medium B for detecting fluorescence of most fluorescent pseudomonads, this report shows that these carbon sources are not equivalent for phytopathogenic pseudomonads

Public Policy on the Introduction of Genetically Engineered Microorganisms

This presentation raises questions of research needs and issues. Underlying assumptions are that only beneficial or useful microorganisms will be released ; that extensive laboratory and contained experiments will have been done prior to introduction and live microorganisms can be confined within the areas of introduction. Evidence to support these assertions will be presented. Critical needs for progress in this area include: 1) Recognition that the nature of the product introduced into the environment is of primary significance, not how the organism was genetically altered or modified. 2) Recognition that microorganisms are introduced into the environment as part of our daily lives. 3) Classification of microorganisms into categories, include a GRACE (Generally Regarded as Compatible with the Environment) list. For example, most microorganisms used by humans in food and agriculture would be on such a list. 4) Categorization of new traits transferred to microorganisms: all are not equal. 5) Revision of the Plant Pest Act. Interpretation by the USDA is now so broad that almost any microorganisms may be a plant pest . 6) Development of the means to enable continuation of basic research in small-scale traditional tests with GEMs. 7) Recognition of the adequacy of the methods used for mitigation and decontamination of microorganisms. 8) Development and use of selective, narrow spectrum chemicals and biologicals. 9) Critical evaluation of appropriate regulations and attendant costs for research on GEMs in the environment. These issues need recognition and wide-spread support among scientists, policy-makers and the public if the potential uses for microorganisms in the environment are to be realized

\u3ci\u3eCorynebacterium nebraskense\u3c/i\u3e, a New, Orange-Pigmented Phytopathogenic Species

A new species of Corynebacterium isolated from field corn is described. The isolates form a homogeneous group that is recognized as a new species, Corynebacterium nebraskense. The organism is characterized by orange-pig-mented colonies, inability to grow on 0.005% triphenyltetrazolium chloride agar, specific bacteriophage sensitivity, and a guanine plus cytosine content of 73.5 mol%. These and other characters differentiate this organism from other described phytopathogenic corynebacteria. The type strain of C. nebraskense is Fur-1 (= ATCC 27822 = NCPPB 2578)

Differential Effects of Lithium Chloride on In Vitro Growth of \u3ci\u3eClavibacter michiganense\u3c/i\u3e subsp. \u3ci\u3enebraskense\u3c/i\u3e Depending upon Inoculum Source

The bacterium Clavibacter michiganense subsp. nebraskense (Corynebacterium michiganense subsp. nebraskense) was grown in broth cultures and inoculated into corn plants. The plating efficiency of cells from broth cultures was essentially the same on nutrient broth-yeast extract and the semiselective medium for this bacterium, CNS. However, when cells were isolated from Goss bacterial wilt- and blight-infected corn, very few were recovered on CNS compared with the amount recovered on nutrient broth-yeast extract agar. When lithium chloride was omitted from the CNS, recoveries from infected corn were nearly the same as on nutrient broth-yeast extract agar. No other ingredient of CNS was inhibitory, nor did substitution of other salts for lithium chloride cause equal inhibition. The amount of inhibition was proportional to lithium chloride concentration. The inhibition by lithium chloride occurred with several strains of the bacterium isolated from one corn cultivar and with one of the strains recovered from three different cultivars of infected cor

Ocurrencia y propiedades de Xanthomonas campestris pv. phaseoli y xanthomonas pestolíticas, epifíticas en malezas

La poblaciones de Xanthomonas campestris pv.phaseoli y otras Xanthomonas atípicas ocurren en forma natural en malezas asintomáticas. Se examinaron 77 muestras de 21 especies de malezas dentro de campos infectados de Tizón común en San Juan, Higuey, Constanza de la República Dominicana. Los aislamientos fueron realizados añadiéndoles 10 ml de bufer (12,5 mM K2 PO4 + 10 mM MgSO4, pH < 7,1). Las pruebas de patogenicidad se realizaron en la variedad de frijol Dark Red Kidney, inoculando a plantas, hojas trifoliadas y legumbres. Para confirmar la reacción de hidrólisis de almidón con metil violeta y metil verde, evaluándose la producción de pigmento marrón y cromatografía de capa fina del pigmento Xanthomonadin. De los resultados observados, se encontraron 14 muestras en 8 especies de malezas para X. campestris pv. phaseoli y 23 especies de malezas para Xanthomonas atípicas.Los aislamientos patogénicos de inoculaciones en hojas a las 2 semanas, la zona amarilla se había expandido y cubría un área amplia alrededor del centro necrótico marrón. Las legumbres de frijol Inoculadas con aislamientos patogénicos mostraron los síntomas típicos alrededor de los 10 días. Todos los aislamientos patogénicos en las hojas fueron patogénicos en el fruto. Ninguno de los aislamientos de malezas colectados después de la cosecha en la zona de Constanza causó síntomas en hojas de frijol. Las muestras de malezas colectadas dentro de campos infectados de Tizón común, tenían más aislamientos patogénicos de X. campestris pv. phaseoli que las muestras que provenían del exterior de los campos o después de la cosecha. El hallazgo de 8 especies de malezas pertenecientes a 6 familias botánicas, las cuales pueden actuar como hospederos sin síntomas, indica que otras especies podrían ser encontradas albergando X. campestris pv. phaseoli epifitas

Nitrogen Fixation (Acetylene Reduction) Associated with Roots of Winter Wheat and Sorghum in Nebraska

Root segments and root-soil cores (6.5-cm diameter) from fields and nurseries of winter wheat and sorghum were tested for N2 fixation by using the acetylene reduction assay. Wheat samples (~1,200) from 109 sites generally had low or no activity (0 to 3.1 nmol of C2H4 produced per h per g [dry weight] of root segments), even after 24 h of incubation. However, a commercial field of Scout 66, located in western Nebraska, exhibited appreciable activity (290 nmol of C2H4 produced per h per g [dry weight] of root segments). Of 400 sorghum lines and crosses, grain sorghums (i.e., CK-60A, Wheatland A, B517, and NP-16) generally exhibited higher nitrogenase activity than forage sorghums or winter wheats. CK-60A, a male sterile grain sorghum, was sampled at four locations and had the most consistent activity of 24 to 1,100 nmol of C2H4 produced per h per core. The maximum rate extrapolated to 2.5 g of N per hectare per day. Numerous N2-fixing bacterial isolates were obtained from wheat and sorghum roots that exhibited high nitrogenase activity. Most isolates were members of the Enterobacteriacae, i.e., Klebsiella pneumoniae, Enterobacter cloacae, and Erwinia herbicola

An Evolutionary Perspective of Pierce’s Disease of Grapevine, Citrus Variegated Chlorosis, and Mulberry Leaf Scorch Diseases

Xylella fastidiosa causes diseases on a growing list of economically important plants. An understanding of how xylellae diseases originated and evolved is important for disease prevention and management. In this study, we evaluated the phylogenetic relationships of X. fastidiosa strains from citrus, grapevine, and mulberry through the analyses of random amplified polymorphic DNAs (RAPDs) and conserved 16S rDNA genes. RAPD analysis emphasized the vigorous genome-wide divergence of X. fastidiosa and detected three clonal groups of strains that cause Pierce’s disease (PD) of grapevine, citrus variegated chlorosis (CVC), and mulberry leaf scorch (MLS). Analysis of 16S rDNA sequences also identified the PD and CVC groups, but with a less stable evolutionary tree. MLS strains were included in the PD group by the 16S rDNA analysis. The Asiatic origins of the major commercial grape and citrus cultivars suggest the recent evolution of both PD and CVC disease in North and South America, respectively, since X. fastidiosa is a New World organism. In order to prevent the development of new diseases caused by X. fastidiosa, it is important to understand the diversity of X. fastidiosa strains, how strains of X. fastidiosa select their hosts, and their ecological roles in the native vegetation

Research on plant disease and pest management is essential to sustainable agriculture

In the United States, a country with food in great abundance, it is difficult to realize that, were it not for the current level of plant disease and pest management, most human resources would be needed to obtain enough food and other plant and animal products merely to survive. Instead, there are surpluses, markets for many agricultural products are depressed, and funds available for research on plant disease and pest management-and for agricultural research generally-have plateaud or are declining. Why does the United States need more research on plant disease and pest management? Because the health and productivity of the crops and cropping systems upon which the people depend for their own consumption and for export cannot be sustained without continuing research and development. This continued investment is needed to manage ever threatening, changing, and rebounding diseases and pest populations. Moreover, disease and pest management of the future must be improved while simultaneously reducing our dependence on pesticides as one of many steps toward the goal of sustainable agriculture. The goal of plant disease and pest management is to ensure that crops are healthy enough to yield to their full genetic potential within the physical limits imposed by the uncontrolled variables of climate, weather, and soils. Management is defined as limiting damage from diseases or pests to a level at or below an acceptable economic or aesthetic threshold. This process does not require total elimination or eradication of the pest or disease problem. Reducing the use of pesticides is a desirable goal, but it depends on continued and increased investments in research on alternatives. For many chemical pesticides, the alternatives either are not yet developed or are less effective than chemicals. This research must be broadly based across the biological, physical, and social sciences. Moreover, the United States and the world depend not only on sustainable agriculture but also on sustainable growth in agriculture to meet a long-term increase in demand for quality and quantity of agricultural products expected from increases in both numbers and economic status of people (Rutan 1992). Furthermore. these increases must \u27be attained at the same time that available agricultural land is decreasing to satisfy other needs such as more land for recreation and urbanization; restoration of some wetlands, grasslands, and woodlands; and diversions of land from farming to other uses. Improved disease and pest management offers one of the few effective means by which the necessary increases in crop productivity can be accomplished while natural resources, including the remaining forests, are protected. These same principles apply to other uses of plants as well, including as ornamentals, for landscapes, and in parks and golf courses