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Antifreeze proteins (AFPs) bind to ice in solutions, resulting in non-colligative freezing point depression; however, their effects on ice nucleation are not well understood. The predominant plasma AFP of winter flounder (Pseudopleuronectes americanus) is AFP6, which is an amphiphilic alpha helix. In this study, AFP6 and modified constructs were produced as fusion proteins in Escherichia coli, subjected to proteolysis when required and purified prior to use. AFP6 and its recombinant fusion precursor generated similar thermal hysteresis and bipyramidal ice crystals, whereas an inactive mutant AFP6 produced hexagonal crystals and no hysteresis. Circular dichroism spectra of the wild-type and mutant AFP6 were consistent with an alpha helix. The effects of these proteins on ice nucleation were investigated alongside non-AFP proteins using a standard droplet freezing assay. In the presence of nucleating AgI, modest reductions in the nucleation temperature occurred with the addition of mutant AFP6, and several non-AFPs, suggesting non-specific inhibition of AgI-induced ice nucleation. In these experiments, both AFP6 and its recombinant precursor resulted in lower nucleation temperatures, consistent with an additional inhibitory effect. Conversely, in the absence of AgI, AFP6 induced ice nucleation, with no other proteins showing this effect. Nucleation by AFP6 was dose-dependent, reaching a maximum at 1.5 mM protein. Nucleation by AFP6 also required an ice-binding site, as the inactive mutant had no effect. Furthermore, the absence of nucleation by the recombinant precursor protein suggested that the fusion moiety was interfering with the formation of a surface capable of nucleating ice., Competing Interests: Declaration of Competing Interest The authors declare no competing financial interest., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Witchweed (Striga hermonthica), also called striga, is a parasitic weed that causes high yield losses in maize on more than 200 000 ha in Kenya alone. A new commercial, biological herbicide developed in Kenya is able to control striga effectively. The product was approved for use by the Pest Control Products Board in Kenya in September, 2021. It is self-produced in villages using a secondary inoculum provided by a commercial company. The formulated product has some disadvantages, which are a complicated production process, a very short shelf life and high application rate. Additionally, the product has to be applied manually and therefore can only be used in manual production, leaving out the opportunity for farmers using mechanization. For this reason, efforts have been made to formulate the active ingredient Fusarium oxysporum f. sp. strigae strain DSM 33471, as a powder and to use it as a seed coating agent. This article deals with the production of the Fusarium spore powder, its properties, its application to the seed, and its herbicidal effect demonstrated in the first two field trials. The F. oxysporum strain was originally isolated from a wilting striga plant in Kenya. The strain was virulence enhanced to over produce the amino acids leucine, methionine and tyrosine. These amino acids are responsible for a second mode of action apart from the wilting causing effect of the fungus on striga. Whereas leucine and tyrosine have a herbicidal effect, ethylene from methionine triggers the germination of striga seeds in the soil. Additionally, the strain has been improved to be resistant to the fungicide captan, which is commonly used to treat maize seed in Kenya. Seed coating tests conducted on 25 striga-infested small holder farms spread out in six counties of western Kenya reported yield increases of up to 88%. A second trial carried out by the Kenyan Agricultural and Livestock Research Organization showed a 93% reduction of emerged striga plants. © 2023 Society of Chemical Industry., (© 2023 Society of Chemical Industry.)

The high-level view of global food systems identifies three all-encompassing barriers to the adoption of food systems solutions: knowledge, policy, and finance. These barriers, and the siloed characteristics of each of these, have hindered the development and adoption of microbial herbicides. How knowledge, policy, and finance are related to the Toothpick Project's path of commercializing a new bioherbicide, early in the scope of the industry, is discussed here. The Toothpick Project's innovation, developed over four decades and commercialized in 2021, uses strains of Fusarium oxysporum f.sp. strigae selected for overproduction and excretion of specific amino acids, killing the parasitic weed Striga hermonthica (Striga or witchweed), Africa's worst pest threat to food security. Historically, bioherbicides have not been a sufficient alternative to the dominant use of synthetic chemical herbicides. To be used safely as bioherbicides, plant pathogens need to be host specific, non-toxic, and yet sufficiently virulent to control a specific weed. For commercialization, bioherbicides must be affordable and require a sufficient shelf life for distribution. Given the current triple storm encountered by the chemical herbicide industry (herbicide-resistant weeds, lawsuits, and consumer pushback), there exists an opportunity to use certain plant pathogens as bioherbicides by enhancing their virulence. By discussing barriers in the scope of knowledge, policy, and finance in the development of the Toothpick Project's new microbial bioherbicide, we hope to help others to anticipate the challenges and provide change-leaders, particularly in policy and finance, a ground level perspective of bioherbicide development. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry., (© 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Potatoes are a dietary staple consumed by a significant portion of the world, providing valuable carbohydrates and vitamins. However, most commercially produced potatoes have a high content of highly branched amylopectin starch, which generally results in a high glycemic index (GI). Consumption of foods with high levels of amylopectin elicit a rapid spike in blood glucose levels, which is undesirable for individuals who are pre-diabetic, diabetic, or obese. Some cultivars of potatoes with lower amylopectin levels have previously been identified and are commercially available in niche markets in some countries, but they are relatively unavailable in the United States and Latin America. The high glycemic index of widely available potatoes presents a problematic "consumer's dilemma" for individuals and families that may not be able to afford a better-balanced, more favorable diet. Some native communities in the Andes (Bolivia, Chile, and Peru) reportedly embrace a tradition of providing low glycemic tubers to people with obesity or diabetes to help people mitigate what is now understood as the negative effects of high blood sugar and obesity. These cultivars are not widely available on a global market. This study examines 60 potato cultivars to identify potatoes with low amylopectin. Three independent analyses of potato starch were used: microscopic examination of granule structure, water absorption, and spectrophotometric analysis of iodine complexes to identify potato cultivars with low amylopectin Differences among cultivars tested were detected by all three types of analyses. The most promising cultivars are Huckleberry Gold, Muru, Multa, Green Mountain, and an October Blue x Colorado Rose cross. Further work is necessary to document the ability of these low amylopectin cultivars to reduce blood glucose spike levels in human subjects., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Rivas et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The winter flounder, Pseudopleuronectes americanus, synthesizes a variety of alpha-helical antifreeze proteins (AFPs) that adhere to ice and inhibit its growth. The best studied of these is AFP6, which is a 37-residue protein abundant in the flounder blood plasma during winter. Curcumin from the turmeric plant (Curcuma longa) was found to interact with AFP6 in aqueous solutions, resulting in measurable changes in the curcumin, but not in the protein. Specifically, the secondary structure and unfolding of synthetic AFP6, shown by circular dichroism, appeared to be unaffected by curcumin. In contrast, the peak absorbance of curcumin shifted and increased in the presence of AFP6, and the maximum fluorescence emission was greater and blue shifted. These results also suggested the possibility of AFP6 detection by curcumin fluorescence. Synthetic AFP6 did not interact with Coomassie blue, silver or a commercial fluorescent stain following electrophoresis; however, the change in curcumin fluorescence upon binding to electrophoresed AFP6 resulted in a fluorescent signal, which was also detected upon interaction with purified natural AFP and flounder blood plasma containing the protein. Thus, aqueous curcumin can be used for the direct detection of AFP6 and curcumin binding could provide new avenues for the study of this protein., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Children whose parent died by suicide are a vulnerable and underserved population. This phenomenon will be described, as well as implications for practice and research. "Double Whammy," a conceptualization of the overall experience of this marginalized group, emerged through two in-depth interviews from a phenomenological qualitative study with professionals who facilitate support groups for children bereaved by parental suicide. It was corroborated with current literature and practice experiences of the authors and their colleagues. Stigma was the largest contributor to the "Double Whammy," and the following themes emerged as well: feeling isolated, feeling abandoned, and feeling responsible. The self-volition of suicide challenges how bereaved children make meaning and internalize feelings about the deceased parent, one's self, and others. Developmentally appropriate education about suicide grief, depression, and normalizing the grief process is pivotal in helping children to effectively cope and manage their feelings.

Certain amino acids induce inhibitory effects in plant growth due to feedback inhibition of metabolic pathways. The inhibition patterns depend on plant species and the plant developmental stage. Those amino acids with inhibitory action on specific weeds could be utilized as herbicides, however, their use for weed control has not been put into practice. Orobanche minor is a weed that parasitizes red clover. O. minor germination is stimulated by clover root exudates. The subsequent seedling is an obligated parasite that must attach quickly to the clover root to withdraw its nutrients. Early development of O. minor is vulnerable to amino acid inhibition and therefore, a series of in vitro , rhizotron, and field experiments were conducted to investigate the potential of amino acids to inhibit O. minor parasitism. In in vitro experiments it was found that among a collection of 20 protein amino acids, lysine, methionine and tryptophan strongly interfere with O. minor early development. Field research confirmed their inhibitory effect but revealed that methionine was more effective than lysine and tryptophan, and that two successive methionine applications at 308 and 543 growing degree days inhibited O. minor emergence in red clover up to 67%. We investigated additional effects with potential to influence the practical use of amino acids against broomrape weeds, whether the herbicidal effect may be reversible by other amino acids exuded by host plants or may be amplified by inducing host resistance barriers against O. minor penetration. This paper suggests that amino acids may have the potential to be integrated into biorational programs of broomrape management.

Striga hermonthica (witchweed) is a parasitic weed that attacks and significantly reduces the yields of maize, sorghum, millet, and sugarcane throughout sub-Saharan Africa. Low cost management methods such as hand weeding, short crop rotations, trap cropping, or conventional biocontrol have not been effective. Likewise, Striga-tolerant or herbicide-resistant maize cultivars are higher yielding, but are often beyond the economic means of sustenance farmers. The fungal pathogen, Fusarium oxysporum f.sp. strigae, has been the object of numerous studies to develop Striga biocontrol. Under experimental conditions this pathogen can reduce the incidence of Striga infestation but field use is not extensive, perhaps because it has not been sufficiently effective in restoring crop yield and reducing the soil Striga seed bank. Here we brought together Kenyan and US crop scientists with smallholder farmers to develop and validate an effective biocontrol strategy for management of Striga on smallholder farms. Key components of this research project were the following: (1) Development of a two-step method of fungal delivery, including laboratory coating of primary inoculum on toothpicks, followed by on-farm production of secondary field inoculum in boiled rice enabling delivery of vigorous, fresh inoculum directly to the seedbed; (2) Training of smallholder farmers (85% women), to produce the biocontrol agent and incorporate it into their maize plantings in Striga-infested soils and collect agronomic data. The field tests expanded from 30 smallholder farmers to a two-season, 500-farmer plot trial including paired plus and minus biocontrol plots with fertilizer and hybrid seed in both plots and; (3) Concerted selection of variants of the pathogen identified for enhanced virulence, as has been demonstrated in other host parasite systems were employed here on Striga via pathogen excretion of the amino acids L-leucine and L-tyrosine that are toxic to Striga but innocuous to maize. This overall strategy resulted in an average of >50% increased maize yield in the March to June rains season and >40% in the September to December rains season. Integration of this enhanced plant pathogen to Striga management in maize can significantly increase the maize yield of smallholder farmers in Kenya.

The Pseudomonas syringae complex is composed of numerous genetic lineages of strains from both agricultural and environmental habitats including habitats closely linked to the water cycle. The new insights from the discovery of this bacterial species in habitats outside of agricultural contexts per se have led to the revelation of a wide diversity of strains in this complex beyond what was known from agricultural contexts. Here, through Multi Locus Sequence Typing (MLST) of 216 strains, we identified 23 clades within 13 phylogroups among which the seven previously described P. syringae phylogroups were included. The phylogeny of the core genome of 29 strains representing nine phylogroups was similar to the phylogeny obtained with MLST thereby confirming the robustness of MLST-phylogroups. We show that phenotypic traits rarely provide a satisfactory means for classification of strains even if some combinations are highly probable in some phylogroups. We demonstrate that the citrate synthase (cts) housekeeping gene can accurately predict the phylogenetic affiliation for more than 97% of strains tested. We propose a list of cts sequences to be used as a simple tool for quickly and precisely classifying new strains. Finally, our analysis leads to predictions about the diversity of P. syringae that is yet to be discovered. We present here an expandable framework mainly based on cts genetic analysis into which more diversity can be integrated.

As a species complex, Pseudomonas syringae exists in both agriculture and natural aquatic habitats. P.viridiflava, a member of this complex, has been reported to be phenotypically largely homogenous. We characterized strains from different habitats, selected based on their genetic similarity to previously described P.viridiflava strains. We revealed two distinct phylogroups and two different kinds of variability in phenotypic traits and genomic content. The strains exhibited phase variation in phenotypes including pathogenicity and soft rot on potato. We showed that the presence of two configurations of the Type III Secretion System [single (S-PAI) and tripartite (T-PAI) pathogenicity islands] are not correlated with pathogenicity or with the capacity to induce soft rot in contrast to previous reports. The presence/absence of the avrE effector gene was the only trait we found to be correlated with pathogenicity of P.viridiflava. Other Type III secretion effector genes were not correlated with pathogenicity. A genomic region resembling an exchangeable effector locus (EEL) was found in S-PAI strains, and a probable recombination between the two PAIs is described. The ensemble of the variability observed in these phylogroups of P.syringae likely contributes to their adaptability to alternating opportunities for pathogenicity or saprophytic survival., (© 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Landscapes influence precipitation via the water vapor and energy fluxes they generate. Biologically active landscapes also generate aerosols containing microorganisms, some being capable of catalyzing ice formation and crystal growth in clouds at temperatures near 0 °C. The resulting precipitation is beneficial for the growth of plants and microorganisms. Mounting evidence from observations and numerical simulations support the plausibility of a bioprecipitation feedback cycle involving vegetated landscapes and the microorganisms they host. Furthermore, the evolutionary history of ice nucleation-active bacteria such as Pseudomonas syringae supports that they have been part of this process on geological time scales since the emergence of land plants. Elucidation of bioprecipitation feedbacks involving landscapes and their microflora could contribute to appraising the impact that modified landscapes have on regional weather and biodiversity, and to avoiding inadvertent, negative consequences of landscape management., (© 2013 John Wiley & Sons Ltd.)

Here, we report the draft genome sequences for 7 phylogenetically diverse isolates of Pseudomonas syringae, obtained from numerous environmental sources and geographically proximate crop species. Overall, these sequences provide a wealth of information about the differences (or lack thereof) between isolates from disease outbreaks and those from other sources.

Nonhost environmental reservoirs of pathogens play key roles in their evolutionary ecology and in particular in the evolution of pathogenicity. In light of recent reports of the plant pathogen Pseudomonas syringae in pristine waters outside agricultural regions and its dissemination via the water cycle, we have examined the genetic and phenotypic diversity, population structure, and biogeography of P. syringae from headwaters of rivers on three continents and their phylogenetic relationship to strains from crops. A collection of 236 strains from 11 sites in the United States, in France, and in New Zealand was characterized for genetic diversity based on housekeeping gene sequences and for phenotypic diversity based on measures of pathogenicity and ice nucleation activity. Phylogenetic analyses revealed several new genetic clades from water. The genetic structure of P. syringae populations was not influenced by geographic location or water chemistry, whereas the phenotypic structure was affected by these parameters. Comparison with strains from crops revealed that the metapopulation of P. syringae is structured into three genetic ecotypes: a crop-specific type, a water-specific type, and an abundant ecotype found in both habitats. Aggressiveness of strains was significantly and positively correlated with ice nucleation activity. Furthermore, the ubiquitous genotypes were the most aggressive, on average. The abundance and diversity in water relative to crops suggest that adaptation to the freshwater habitat has played a nonnegligible role in the evolutionary history of P. syringae. We discuss how adaptation to the water cycle is linked to the epidemiological success of this plant pathogen.

High-yielding cereals and other staples have produced adequate calories to ward off starvation for much of the world over several decades. However, deficiencies in certain amino acids, minerals, vitamins and fatty acids in staple crops, and animal diets derived from them, have aggravated the problem of malnutrition and the increasing incidence of certain chronic diseases in nominally well-nourished people (the so-called diseases of civilization). Enhanced global nutrition has great potential to reduce acute and chronic disease, the need for health care, the cost of health care, and to increase educational attainment, economic productivity and the quality of life. However, nutrition is currently not an important driver of most plant breeding efforts, and there are only a few well-known efforts to breed crops that are adapted to the needs of optimal human nutrition. Technological tools are available to greatly enhance the nutritional value of our staple crops. However, enhanced nutrition in major crops might only be achieved if nutritional traits are introduced in tandem with important agronomic yield drivers, such as resistance to emerging pests or diseases, to drought and salinity, to herbicides, parasitic plants, frost or heat. In this way we might circumvent a natural tendency for high yield and low production cost to effectively select against the best human nutrition. Here we discuss the need and means for agriculture, food processing, food transport, sociology, nutrition and medicine to be integrated into new approaches to food production with optimal human nutrition as a principle goal.

A considerable number of plant pathogens have been studied for their possible use in weed control. Some have proven virulent enough to control weed species and to compete commercially with chemical herbicides. However, most pathogens of weeds are not useful in their wild form because they are not sufficiently host-specific and/or virulent. The authors believe that these barriers can be overcome. The present research has focused on the inhibitory effects of certain amino acids on the growth and development of specific plants. Pathogens that overproduce these selected amino acids can be easily selected from a pool of spontaneous mutants. Such mutants can have increased pathogenicity to their target weed and enhanced field performance as biocontrol agents. Enhancement of biocontrol efficacy in three separate pathogen-host systems, two with Fusarium and one with Pseudomonas, has already been reported. It is proposed to use the same technology to enhance the biocontrol efficacy of the two species of Fusarium that are host-specific pathogens of the broomrape group of parasitic weeds. The stepwise approach outlined can lead to obtaining enhanced biocontrol agents capable of producing inhibitory levels of selected amino acids in situ. It is proposed that these approaches, in combination with other methods of virulence enhancement, will lead to sustainable systems of biological control of parasitic weeds.

Biological ice nucleators (IN) function as catalysts for freezing at relatively warm temperatures (warmer than -10 degrees C). We examined the concentration (per volume of liquid) and nature of IN in precipitation collected from Montana and Louisiana, the Alps and Pyrenees (France), Ross Island (Antarctica), and Yukon (Canada). The temperature of detectable ice-nucleating activity for more than half of the samples was > or = -5 degrees C based on immersion freezing testing. Digestion of the samples with lysozyme (i.e., to hydrolyze bacterial cell walls) led to reductions in the frequency of freezing (0-100%); heat treatment greatly reduced (95% average) or completely eliminated ice nucleation at the measured conditions in every sample. These behaviors were consistent with the activity being bacterial and/or proteinaceous in origin. Statistical analysis revealed seasonal similarities between warm-temperature ice-nucleating activities in snow samples collected over 7 months in Montana. Multiple regression was used to construct models with biogeochemical data [major ions, total organic carbon (TOC), particle, and cell concentration] that were accurate in predicting the concentration of microbial cells and biological IN in precipitation based on the concentration of TOC, Ca(2+), and NH(4)(+), or TOC, cells, Ca(2+), NH(4)(+), K(+), PO(4)(3-), SO(4)(2-), Cl(-), and HCO(3)(-). Our results indicate that biological IN are ubiquitous in precipitation and that for some geographic locations the activity and concentration of these particles is related to the season and precipitation chemistry. Thus, our research suggests that biological IN are widespread in the atmosphere and may affect meteorological processes that lead to precipitation.

Pseudomonas syringae is a plant pathogen well known for its capacity to grow epiphytically on diverse plants and for its ice-nucleation activity. The ensemble of its known biology and ecology led us to postulate that this bacterium is also present in non-agricultural habitats, particularly those associated with water. Here, we report the abundance of P. syringae in rain, snow, alpine streams and lakes and in wild plants, in addition to the previously reported abundance in epilithic biofilms. Each of these substrates harbored strains that corresponded to P. syringae in terms of biochemical traits, pathogenicity and pathogenicity-related factors and that were ice-nucleation active. Phylogenetic comparisons of sequences of four housekeeping genes of the non-agricultural strains with strains of P. syringae from disease epidemics confirmed their identity as P. syringae. Moreover, strains belonging to the same clonal lineage were isolated from snow, irrigation water and a diseased crop plant. Our data suggest that the different substrates harboring P. syringae modify the structure of the associated populations. Here, we propose a comprehensive life cycle for P. syringae--in agricultural and non-agricultural habitats--driven by the environmental cycle of water. This cycle opens the opportunity to evaluate the importance of non-agricultural habitats in the evolution of a plant pathogen and the emergence of virulence. The ice-nucleation activity of all strains from snow, unlike from other substrates, strongly suggests that P. syringae plays an active role in the water cycle as an ice nucleus in clouds.

Despite the integral role of ice nucleators (IN) in atmospheric processes leading to precipitation, their sources and distributions have not been well established. We examined IN in snowfall from mid- and high-latitude locations and found that the most active were biological in origin. Of the IN larger than 0.2 micrometer that were active at temperatures warmer than -7 degrees C, 69 to 100% were biological, and a substantial fraction were bacteria. Our results indicate that the biosphere is a source of highly active IN and suggest that these biological particles may affect the precipitation cycle and/or their own precipitation during atmospheric transport.

The biology and ecology of plant pathogenic bacteria have been studied almost exclusively in agricultural contexts. In contrast, for numerous human pathogens their biological activity in niches outside of medical contexts is well-known. Whereas there is increasing evidence that traits fostering survival in 'environmental' niches can be the basis for virulence factors of human pathogens, niches for plant pathogenic bacteria outside of plants or of agricultural settings have not been elucidated. Most phytopathogenic bacteria are not obligate parasites, some of them can be transported to altitudes of several kilometres, they are scrubbed from the atmosphere by rainfall, and thus they are presumably transported to and might survive in a wide range of habitats. We isolated Pseudomonas syringae from river epilithon (rock-attached biofilms composed of algae, diatoms, rotifers, bacteria and nematodes) at densities up to 6000 cells g(-1) in France and the USA, some in pristine settings where waters flowed directly from snow melt and had not passed through agricultural zones. These strains induced hypersensitivity in indicator plants (tobacco) suggesting the presence of functional pathogenicity systems, and many induced disease in 1-7 of the plant species tested and produced a syringomycin-like toxin. Strains also were resistant to some antibiotics used to control plant diseases but not to copper sulphate. Sequencing of the 16S rDNA of epilithon strains and of reference strains of P. syringae revealed that a genetic lineage containing the strains with the broadest host range was distributed across several continents. Is it likely that wide spread dissemination of P. syringae occurs via aerosols and precipitation. This work highlights our limited understanding of non-agricultural niches in the ecology and evolution of plant pathogenic bacteria, of their role in the development of agricultural epidemics both as sources of inoculum and as sources of novel traits that may enhance bacterial pathogenicity and fitness.

Acroptilon repens (L.) DC. (Russian knapweed) is a long-lived perennial weed from central Asia that is widely distributed in the western United States (U.S.). Recently, accessions of a rust disease were collected from Colorado (CO), Montana (MT), and Wyoming (WY) for comparison with Eurasian isolates. U.S. accessions had two-celled teliospores with slight constrictions in the middle and urediniospores with three germ pores ± equatorial in location. Urediniospores were (state, width × length, [n = 100]): CO, 16.4 to 25.7 × 19.2 to 27.0 μm; MT, 18.4 to 23.1 × 17.4 to 24.6 μm; and WY, 18.0 to 26.2 × 20.2 to 26.7 μm. These were similar to those of 16.6 to 25.7 × 21.2 to 28.0 μm from two New Mexican (NM) herbarium specimens (BPI Nos. 1107952 and 1110177) (1). Teliospores measured 19.9 to 27.7 × 29.8 to 47.4 μm, 17.4 to 26.0 × 32.4 to 44.2 μm, 16.5 to 27.5 × 29.4 to 45.7 μm, and 18.7 to 27.6 × 31.0 to 46.4 μm for CO, MT, WY, and NM accessions, respectively. These rust isolates have been identified as Puccinia acroptili Syd. on the basis of host plant record and spore morphology (2). To our knowledge, this is the first record of P. acroptili in CO, MT, and WY. Besides NM, P. acroptili has been reported in North America from California, British Columbia, and Saskatchewan. References: (1) M. E. Palm and S. G. Vesper. Plant Dis. 75:1075, 1991. (2) D. B. O. Savile. Can. J. Bot. 48:1567, 1970.

ABSTRACT Strains of Pantoea agglomerans (synanamorph Erwinia herbicola) suppressed the development of basal kernel blight of barley, caused by Pseudomonas syringae pv. syringae, when applied to heads prior to the Pseudomonas syringae pv. syringae infection window at the soft dough stage of kernel development. Field experiments in 1994 and 1995 revealed 45 to 74% kernel blight disease reduction, whereas glasshouse studies resulted in 50 to 100% disease control depending on the isolate used and barley cultivar screened. The efficacy of biocontrol strains was affected by time and rate of application. Percentage of kernels infected decreased significantly when P. agglomerans was applied before pathogen inoculation, but not when coinoculated. A single P. agglomerans application 3 days prior to the pathogen inoculation was sufficient to provide control since populations of about 10(7) CFU per kernel were established consistently, while Pseudomonas syringae pv. syringae populations dropped 100-fold to 2.0 x 10(4) CFU per kernel. An application to the flag leaf at EC 49 (before heading) also reduced kernel infection percentages significantly. Basal blight decreased with increasing concentrations (10(3) to 10(7) CFU/ml) of P. agglomerans, with 10(7) CFU/ml providing the best control. For long-term preservation and marketability, the survival of bacterial antagonists in several wettable powder formulations was tested. Over all formulations tested, the survival declined between 10- to >100-fold over a period of 1.5 years (r = -0.7; P = 0.000). Although not significant, storage of most formulations at 4 degrees C was better for viability (90 to 93% survival) than was storage at 22 degrees C (73 to 79%). However, long-term preservation had no adverse effect on biocontrol efficacy.

A new forma specialis of Fusarium oxysporum (F. oxysporum f. sp. erythroxyli) pathogenic to Erythroxylum coca and E. novogranatense is described. The pathogen was isolated from the vascular tissue of diseased plants from an Erythroxylum plantation in Hawaii. This pathogen causes vascular wilt symptoms and death in both E. coca and E. novogranatense plants as soon as 7 weeks after soil infestation. The pathogenicity of seven isolates from the affected field was determined in field and growth-chamber studies. Genetic variation was not detected among the seven Hawaiian isolates, using arbitrarily primed polymerase chain reaction. The seven isolates could be differentiated from a strain isolated from a diseased E. coca plant from South America. All Hawaiian isolates and the South American isolate belonged to a single vegetative compatibility group.

The epiphytic populations of Pseudomonas syringae were monitored on 23 barley entries planted in the field in four replications during the summer of 1986, and on six selected entries during the summer of 1987, from the second-leaf stage until senescence. Populations were initially low (0-3 log colony-forming units (cfu) per leaf) in all but one entry; they generally increased throughout the season, and at the end they reached 3-7 log cfu/leaf. Significant differences among the average epiphytic populations were found in the 1986 trial; only one entry, however, had a significantly different average population in the 1987 trial. The slopes of population increase were also compared: significant differences were observed in 1986 but not in 1987. In addition to epiphytic population counts, the percentage of ice nucleation active bacteria was determined in the population isolated from each leaf sample, and averaged throughout the season for each entry. Significant differences were observed in 1986 and in 1987. When the entries were ranked according to their average epiphytic population and compared between the two experiments, they were found to be very similar. The same was not true for the other parameters studied in the experiment.

To obtain rhizosphere-competent bacteria which could subsequently be modified for the development of biological control agents, bacteria were isolated from the rhizosphere and rhizoplane of wheat and barley plants by standard techniques. Of these isolates, 60 were selected for field testing as spring wheat seed inoculants in 1985. Isolates were marked genetically for resistance to antibiotics via selection of spontaneous mutants to detect and monitor isolates in the field. Forty-three days after planting, the average log(10) CFU/mg (dry weight) of roots and rhizosphere soil for the mutant isolates sampled ranged from 0 to 3.4. Twenty mutant isolates were retested in 1986. A total of 4 isolates were not detected, but the other 16 had an average root colonization value of log(10) 2.1 CFU and a range of log(10) 0.9 CFU to log(10) 3.2 CFU when sampled 32 days after planting. The average colonization value dropped to log(10) 1.1 CFU 51 days later. Some isolates detected previously were not detected in the second sampling; others had root colonization values similar to those obtained in the first sampling. Mutant isolates of rhizosphere bacteria included Bacillus pumilus, Bacillus subtilis, Pseudomonas fluorescens, Streptomyces spp., Xanthomonas maltophilia, and a saprophytic coryneform. Mixtures of isolates from different genera and species were compatible on seeds and roots.

Lysine analogues are used to select for lysine-excreting mutants of Lactobacillus plantarum. The use of lactobacilli that excrete lysine for the enrichment of foods and feedstuffs by fermentation is discussed. The increase in lysine content of soybean milk by a mutant of L. bulgaricus and in silage by L. plantarum is shown.

Fermentation is known to modify nutritional value of foods positively. A new technique for supplementing traditional fermented foods with limiting amino acids is presented. Normal fermentative bacteria are induced to produce specific amino acids during the fermentation period. Acceptable food products have been prepared using fermented grain. The concept may be applicable to developing countries.

Penicillium urticae (NRRL 2159A) was grown in culture broth containing 1 muCi of [1-14C-A1acetate to produce [14C]patulin. [14C]patulin was purified from the broth and added to apple cider. After the patulin concentration of the cider was adjusted to 30 mug/ml with unlabeled patulin, the cider was subjected to various charcoal treatments. [14C]patulin was completely removed by shaking the cider with 20 mg of activated charcoal per ml and by eluting the cider through a 40- to 60-mesh charcoal column. Activated charcola at 5 mg/ml reduced patulin in naturally contaminated cider to nondetectable levels.

Broiler chicks were provided choices of synthetic diets (a) adequate or low in lysine, and (b) adequate in or devoid of lysine. In each case, chicks consumed some of each diet offered, but preference was shown for the adequate lysine diet. Growth rates of chicks given choices ranged from 80% of that of chicks fed an adequate lysine diet with no choice for two weeks, then growth rates fell to about 60% of those fed adequate lysine. In another study, chicks were fed a diet devoid of lysine but were offered pure L-lysine HCl in a separate feeder. These chicks selected some of the supplementary lysine, but their body weights were only 68% of the body weight of chicks fed an adequate lysine diet after 21 days. Chicks given a choice of diets prepared with an adequate quantity of either L- or D-lysine preferred with L-lysine diet but did not select sufficient quantity to reach normal growth. These observations indicate that chicks can discern the presence of L-lysine in diets or separately, but will not select sufficient quantity for maximum growth potential. A diet prepared with D-lysine was more acceptable than one completely devoid of lysine, suggesting some sensory recognition for lysine.

Production of carbohydrases by Alternaria solani is inhibited by glucose under low growth conditions. In an enriched medium, glucose has little effect on the production of polygalacturonase and cellulase while it still suppresses production of beta-glucosidase. Low levels of all three enzymes were produced in the absence of their respective substrates. Such regulation has been found with many organisms. However, far greater production of these carbohydrases occurred with additions of adenosine phosphates to the growth media. Highest stimulation of enzyme production was by adenosine 5'-phosphate. Adenosine 5'-triphosphate and cyclic 3', 5'-adenosine monophosphate gave lesser amounts. Starvation appears to induce production of extracellular carbohydrases and adenosine 5'-phosphate may have a role in the starvation process.

Proteases, lipase, and chitinase killed Tylenchorhynchus dubius in vitro and in soil. Tylenchorhynchus dubius was more susceptible to the enzymes than Pratylenchus penetrans. Papain was the most effective protease, and other enzymes were less effective. Heating enzymes to 80 C for 10 min greatly reduced nematicidal effectiveness. Scanning electron micrographs showed that papain and chitinase produced structural changes in the cuticle of T. dubius. Lipase removed a thin outer layer. Papain removed material filling the striata, or furrow, between the horizontal bands. When added to soil, chitinase, lipase, collagenase, and proteases (papain and bromelain) decreased motility of T. dubius populations up to 75%. Bromelain was the most active in soil against T. dubius, and collagenase was the most active in soil against P. penetrans.

Incorporation of novobiocin, penicillin, and cycloheximide into a standard medium for fluorescence selects for fluorescent pathogenic and free-living pseudomonads.

Phytopathogenic pseudomonads were placed into four major groups on the basis of nutritional and physiological characteristics. Group I consists of 86 strains of phytopathogens distinguishable from other fluorescent pseudomonads by low growth rates, ability to induce hypersensitivity on tobacco, absence of arginine dihydrolase, and relatively limited ranges of carbon sources. Most of these strains cannot utilize benzoate, 2-ketogluconate, spermine, beta-alanine, l-isoleucine, l-valine, and l-lysine. Most of the organisms in group I clustered into a small number of subgroups, each of which generally corresponded to a previously recognized nomenspecies. These subgroups differ with respect to the number of substrates used. As a rule, the organisms that utilize the fewest substrates have the most limited host ranges. The fluorescent pseudomonads of group II are arginine dihydrolase-positive and utilize a considerably larger number of carbon sources. Most pathogens of group II are similar to Pseudomonas fluorescens biotype A. Groups III and IV consist of nonfluorescent pseudomonads. These two groups can be distinguished by the number of carbon sources used and by pigmentation. An amended description of the flurescent pseudomonads and their internal subdivision is presented.

An improved solid agar medium (MP medium) has been developed which allows detection of pectolytic activity in bacteria. Organisms tested exhibited a variety of regulatory controls governing pectate lyase synthesis. The medium contains mineral salts, pectin, and yeast extract. After growth of the organisms, the agar plate is flooded with a polysaccharide precipitant, and pectolytic activity is shown by clear zones around active colonies. High concentrations of phosphate are shown to be necessary for pectic enzyme formation on solid media. The medium has successfully been used to detect pectolytic organisms in soil, forest litter, and rotting vegetable samples.