Interaction of Fusarium Wilt Race 4 with Root-Knot Nematode Increases Disease Severity in Cotton.

Fusarium wilt, caused by Fusarium oxysporum f. sp. vasinfectum, is a severe disease of cotton (Gossypium spp.). Strains of the wilt pathogen in the United States, such as race 1, require the presence of nematodes such as southern root-knot nematode (Meloidogyne incognita) to cause appreciable disease. The exception is the race 4 strain of the wilt pathogen, which can attack cotton without concomitant infection by plant-parasitic nematodes and was first identified in California in 2001 and in Texas and New Mexico since 2017. The effects of the interaction between M. incognita and race 1 or race 4 on wilt severity and nematode reproduction on two Gossypium hirsutum cultivars, Acala 44 and FM 966, and a G. barbadense cultivar, Pima S-4, were directly compared in growth chamber assays. All three cultivars were susceptible to M. incognita. Suppression of nematode reproduction by the wilt pathogen was detected only for race 4 on all three cultivars on a per plant basis but not on a per gram root tissue basis. The control, M. incognita alone, and race 1 alone treatments caused no symptoms. Inoculation with race 1 and M. incognita caused moderate wilt symptoms in 'Acala 44' and 'FM 966' and mild symptoms in 'Pima S-4'. However, race 4 treatment caused severe wilt in 'Pima S-4' and moderate wilt severity in 'Acala 44' and 'FM 966'. The symptom severity of 'Acala 44' and 'FM 966' further increased in the presence of M. incognita. Thus, race 4 is not only capable of causing wilt in the absence of M. incognita but can also interact with the nematode to further increase disease severity. Though control of wilt caused by race 1 can be achieved mainly through breeding for nematode resistance, it will be imperative to incorporate both southern root-knot nematode and race 4 resistance to effectively control the disease should race 4 expand into southern root-knot nematode-infested fields.

Consumption of a Variety of Vegetables to Meet Dietary Guidelines for Americans' Recommendations Does Not Induce Sensitization of Vegetable Reinforcement Among Adults with Overweight and Obesity: A Randomized Controlled Trial.

BACKGROUND: Food reinforcement, or the motivation to obtain food, can predict choice and consumption. Vegetable consumption is well below recommended amounts for adults, so understanding how to increase vegetable reinforcement could provide valuable insight into how to increase consumption. OBJECTIVES: We sought to determine whether daily consumption of the Dietary Guidelines for Americans (DGA) recommendations for vegetable intake induces sensitization of vegetable reinforcement in adults with overweight and obesity. METHODS: Healthy adults with a BMI ≥ 25 kg/m2 who consumed ≤1 cup-equivalent of vegetables/day were randomly assigned to a vegetable intervention (VI; n = 55) or an attention control (AC; n = 55) group. The VI consisted of the daily provision of vegetables in the amounts and types recommended by the DGA (∼270 g/day) for 8 weeks. Participants were followed for an additional 8 weeks to assess sustained consumption. Compliance was measured weekly by resonance Raman light-scattering spectroscopy (RRS). Vegetable reinforcement was tested at weeks 0, 8, 12, and 16 using a computer choice paradigm. RESULTS: In the VI group, RRS intensity increased from week 0 to 8 (from 22,990 to 37,220), returning to baseline by week 16 (27,300). No change was observed in the AC group. There was no main effect of treatment (P = 0.974) or time (P = 0.14) and no treatment x time interaction (P = 0.44) on vegetable reinforcement. There was no moderating effect of sex (P = 0.07), age (P = 0.60), BMI (P = 0.46), delay discounting (P = 0.24), 6-n-propylthiouracil taster status (P = 0.15), or dietary disinhibition (P = 0.82) on the change in vegetable reinforcement. CONCLUSIONS: These findings suggest no effects of the provision of a variety of vegetables to meet DGA recommendations for 8 weeks on vegetable reinforcement and highlight the difficulty in increasing vegetable consumption in adults. This trial was registered at clinicaltrials.gov as NCT02585102.

Genetic Diversity and Pathogenicity of Verticillium dahliae Isolates and Their Co-occurrence with Fusarium oxysporum f. sp. vasinfectum Causing Cotton Wilt in Xinjiang, China.

Cotton production in Xinjiang, the largest cotton-producing area in China, has an increasingly serious disease threat from Verticillium dahliae. Eighty-five V. dahliae isolates were obtained from wilted cotton plants collected from eight counties in Xinjiang. The isolates were assessed for genotypic diversity by DNA sequence analysis and PCR molecular genotyping with specific markers for race 1, race 2, defoliating (D) pathotype, nondefoliating (ND) pathotype, and mating type idiomorph Mat1-2. Isolates belonged to lineages 1A or 2B, with three subgenotypes found in each lineage. All isolates tested positive for race 2 and Mat1-2 markers. All isolates in lineage 2B tested positive for the ND pathotype marker but only isolates in the major subgenotype in lineage 1A tested positive for the D pathotype marker. Pathogenicity assays on Gossypium hirsutum 'Acala 44' demonstrated no significant difference among subgenotypes within each lineage. Isolates in lineage 1A caused greater shoot weight reductions, percent leaf drop, and percent diseased leaves than isolates in lineage 2B. One isolate in each lineage for 1A and 2B was avirulent. Isolates in lineage 1A caused greater than 50% leaf drop and a 17-g shoot weight reduction compared with a 9% leaf drop and a 6-g shoot weight reduction by isolates in lineage 2B. Overall, 42% of the V. dahliae isolates from Xinjiang were D pathotype but the percentage varied widely among locations. Two plants had both pathotypes. Nineteen isolates of Fusarium oxysporum f. sp. vasinfectum VCG0114 (race 4) also were recovered from wilted plants in Xinjiang. Two plants had both Verticillium wilt and Fusarium wilt pathogens. Both pathogens should be considered when using or developing wilt resistant or tolerant materials for Xinjiang.

Relationship Between Piercing-Sucking Insect Control and Internal Lint and Seed Rot in Southeastern Cotton (Gossypium hirsutum L.).

In 1999, crop consultants scouting for stink bugs (Hemiptera spp.) in South Carolina discovered a formerly unobserved seed rot of cotton that caused yield losses ranging from 10 to 15% in certain fields. The disease has subsequently been reported in fields throughout the southeastern Cotton Belt. Externally, diseased bolls appeared undamaged; internally, green fruit contain pink to dark brown, damp, deformed lint, and necrotic seeds. In greenhouse experiments, we demonstrated transmission of the opportunistic bacterium Pantoea agglomerans by the southern green stink bug, Nezara viridula (L.). Here, green bolls were sampled from stink bug management plots (insecticide protected or nontreated) from four South Atlantic coast states (North Carolina, South Carolina, Georgia, and Florida) to determine disease incidence in the field and its association with piercing-sucking insects feeding. A logistic regression analysis of the boll damage data revealed that disease was 24 times more likely to occur (P = 0.004) in bolls collected from plots in Florida, where evidence of pest pressure was highest, than in bolls harvested in NC with the lowest detected insect pressure. Fruit from plots treated with insecticide, a treatment which reduced transmission agent numbers, were 4 times less likely to be diseased than bolls from unprotected sites (P = 0.002). Overall, punctured bolls were 125 times more likely to also have disease symptoms than nonpunctured bolls, irrespective of whether or not plots were protected with insecticides (P = 0.0001). Much of the damage to cotton bolls that is commonly attributed to stink bug feeding is likely the resulting effect of vectored pathogens.

Conversion of fusaric acid to Fusarinol by Aspergillus tubingensis: a detoxification reaction.

The fungus Fusarium oxysporum causes wilt diseases of plants and produces a potent phytotoxin fusaric acid (FA), which is also toxic to many microorganisms. An Aspergillus tubingensis strain with high tolerance to FA was isolated from soil and designated as CDRAt01. HPLC analysis of culture filtrates from A. tubingensis isolate CDRAt01 grown with the addition of FA indicated the formation of a metabolite over time that was associated with a decrease of FA. Spectral analysis and chemical synthesis confirmed the compound as 5-butyl-2-pyridinemethanol, referred to here as fusarinol. The phytotoxicity of fusarinol compared to FA was measured by comparing necrosis induced in cotton (Gossypium hirsutum L. cv. Coker 312) cotyledons. Fusarinol was significantly less phytotoxic than FA. Therefore, the A. tubingensis strain provides a novel detoxification mechanism against FA which may be utilized to control Fusarium wilt.

Root distribution and potential interactions between allelopathic rice, sprangletop (Leptochloa spp.), and barnyardgrass (Echinochloa crus-galli) based on ¹³C isotope discrimination analysis.

Weed-suppressive rice cultivars hold promise for improved and more economical weed management in rice. Interactions between roots of rice and weeds are thought to be modulated by the weed-suppressive activity of some rice cultivars, but these phenomena are difficult to measure and not well understood. Thus, above-ground productivity, weed suppression, and root distribution of 11 rice cultivars and two weed species were evaluated in a drill-seeded, flood-irrigated system at Stuttgart, Arkansas, USA in a two-year study. The allelopathic cultivars, PI 312777 and Taichung Native 1 (TN-1), three other weed-suppressive cultivars, three indica-derived breeding selections, and three non-suppressive commercial cultivars were evaluated in field plots infested with barnyardgrass (Echinochloa crus-galli (L.) Beauv.) or bearded sprangletop (sprangletop, Leptochloa fusca (L.) Kunth var. fascicularis (Lam.) N. Snow). The allelopathic cultivars produced more tillers and suppressed both weed species to a greater extent than did the breeding selections or the non-suppressive cultivars. (13)C isotope discrimination analysis of mixed root samples to a depth of 15 cm revealed that the allelopathic cultivars typically produced a greater fraction of their total root mass in the surface 0-5 cm of soil depth compared to the breeding selections or the non-suppressive cultivars, which tended to distribute their roots more evenly throughout the soil profile. These trends in root mass distribution were apparent at both early (pre-flood) and late-season stages in weed-free and weed-infested plots. Cultivar productivity and root distribution generally responded similarly to competition with the two weed species, but barnyardgrass reduced rice yield and root mass more than did sprangletop. These findings demonstrate for the first time that roots of the allelopathic cultivars PI 312777 and TN-1 explore the upper soil profile more thoroughly than do non-suppressive cultivars under weed-infested and weed-free conditions in flood-irrigated U.S. rice production systems. They raise the interesting prospect that root proliferation near the soil surface might enhance the weed-suppressive activity of allelochemical exudates released from roots. Plant architectural design for weed suppressive activity should take these traits into consideration along with other proven agronomic traits such as high tillering and yield.

A new formulation of screwworm fly attractant with reduced hazardous chemicals and transport restrictions.

New World screwworm flies, Cochliomyia hominivorax (Coquerel), are obligate parasites of warm-blooded animals. They were eradicated from North and Central America during the mid-20th to early-21st centuries using the sterile insect technique (SIT), a method presently employed to maintain a permanent barrier between Central and South America. Lures are an important component of the screwworm eradication program, where they are used for surveillance, sample collection, and strain evaluation in the field. The first chemical lure, later named swormlure, was developed based on the attractiveness of C. hominivorax to volatile organic compounds (VOCs) produced from decomposing animal tissues. The formulation has changed little over the years and presently contains 10 chemicals, one of which is dimethyl disulfide (DMDS). Restrictions on the transport of DMDS have recently impeded its use in swormlure-4 (SL-4). However, dimethyl trisulfide (DMTS) is not as highly restricted and can be shipped via air transportation. Both chemicals are produced by microbial decomposition of animal tissues. Here, we conducted field trials using three releases of sterile C. hominivorax, each comprising approximately 93,000 flies, to test the efficacy of SL-4, containing DMDS, to swormlure-5 (SL-5) containing DMTS. Traps baited with SL-4 and SL-5 captured 575 (mean = 191.7, SD 17.9) and 665 (mean = 221.7, SD 33.2) C. hominivorax, respectively (df = 19, F = 1.294, P = 0.269). However, traps baited with SL-5 captured considerably more Cochliomyia macellaria (Fabricius), a closely related but nontarget fly.

Consumption of Dietary Guidelines for Americans Types and Amounts of Vegetables Increases Mean Subjective Happiness Scale Scores: A Randomized Controlled Trial.

BACKGROUND: The health benefits of diets rich in fruits and vegetables (FV) are well established. Recent observational and intervention research suggests that FV consumption may also exert a positive effect on psychological well-being. OBJECTIVE: This study aimed to assess changes in mean Subjective Happiness Scale (SHS) scores in response to consuming 2010-2015 Dietary Guidelines for Americans (DGA) recommended types and amounts of vegetables. It was hypothesized that increased vegetable consumption would increase mean SHS scores. DESIGN: This study investigated a secondary outcome of a randomized, parallel, nonblinded controlled trial with a 1:1 allocation ratio to a provided vegetable intervention or attention control group. PARTICIPANTS/SETTING: Men and women (n = 75) aged 18 to 65 years, body mass index ≥ 25, with low habitual vegetable consumption were recruited from Grand Forks, North Dakota, December 2016 to January 2018, for this community-based study. INTERVENTION: The vegetable intervention consisted of an 8-week feeding phase during which participants were provided with vegetables in DGA-recommended types and amounts. The attention control group was not provided vegetables but completed the same testing schedule as the vegetable intervention group. MAIN OUTCOME MEASURE: Mean SHS scores were assessed before and after the intervention. STATISTICAL ANALYSES: Mean SHS scores were analyzed using a 2-way factorial mixed linear model analysis of variance. RESULTS: A significant interaction between treatment and visit (P = .015) revealed greater mean SHS scores at week 8 than at baseline in the vegetable intervention group (+0.23 ± 0.11) (mean difference ± SE of the difference) but no change in the attention control group (-0.15 ± 0.11). CONCLUSIONS: Greater mean SHS scores were observed after increasing vegetable consumption to meet DGA recommendations, suggesting that adhering to DGA vegetable guidance may help promote psychological well-being.

Incorporating the Dietary Guidelines for Americans Vegetable Recommendations into the Diet Alters Dietary Intake Patterns of Other Foods and Improves Diet Quality in Adults with Overweight and Obesity.

BACKGROUND: Understanding how vegetables are incorporated into the diet, especially in the types and amounts recommended by the Dietary Guidelines for Americans, and how this alters dietary intake patterns is vital for developing targeted behavior change interventions. OBJECTIVE: To determine how a provision of vegetables was incorporated into the diet of adults with overweight and obesity; whether or not the provided vegetables displaced other foods; and what, if any, effect this had on diet quality and body weight and composition. DESIGN: This study investigated secondary outcomes from the Motivating Value of Vegetables Study, a community-based, randomized, parallel, nonblinded controlled trial. Participants were randomly assigned to a provided vegetable intervention or attention control group using a one to one allocation ratio. PARTICIPANTS/SETTING: Men and women with self-reported low vegetable consumption, aged 18 to 65 years, with a body mass index ≥25 were recruited from Grand Forks, ND, between October 2015 and September 2017. Only participants randomized to the provided vegetable intervention group (n = 51; attrition = 8%) were included in this secondary analysis. INTERVENTION: Dietary Guidelines for Americans recommended types and amounts of vegetables were provided weekly for 8 weeks. MAIN OUTCOME MEASURES: How the provided vegetables were incorporated into the diet was measured using daily self-report and 24-hour dietary recalls. Diet quality was assessed via the Healthy Eating Index 2015. Body weight and composition were measured before and after the intervention. STATISTICAL ANALYSES PERFORMED: Data were assessed using generalized linear mixed models where phase (pre, post) was the within-subject factor and subject was the random effect. RESULTS: Participants self-reported using 29% of the provided vegetables as substitutes for other foods. With the increase in vegetable consumption, there were decreases in total grains (mean difference ± standard deviation; -0.97 ± 3.23 oz-equivalents; P = 0.02), protein foods (-1.24 ± 3.86 oz-equivalents; P = 0.01), saturated fats (-6.44 ± 19.63 g; P = 0.02), and added sugars (-2.44 ± 6.78 tsp-equivalents; P = 0.02) consumed. Total Healthy Eating Index 2015 scores increased (+4.48 ± 9.63; P = 0.001) and dietary energy density decreased (-0.44 ± 0.52 kcal/g; P < 0.0001). There was no change in total energy intake or body weight and composition. CONCLUSIONS: Increasing vegetable consumption to meet Dietary Guidelines for Americans recommendations alters dietary intake patterns, improving diet quality and energy density. These findings highlight the importance of characterizing how individuals incorporate Dietary Guidelines for Americans recommendations into their diet.

Characterization of Salmonella enterica isolates from turkeys in commercial processing plants for resistance to antibiotics, disinfectants, and a growth promoter.

Salmonella enterica isolates from turkeys in two commercial processing plants (1 and 2) were characterized for susceptibility to antibiotics, disinfectants, and the organoarsenical growth promoter, 4-hydroxy-3-nitrophenylarsonic acid (3-NHPAA, roxarsone), and it's metabolites, NaAsO(2) (As(III)) and Na(2)HAsO(4) • 7H(2)O (As(V)). The 130 Salmonella serovars tested demonstrated a low incidence of resistance to the antibiotics gentamicin (GEN), kanamycin (KAN), sulfamethoxazole (SMX), streptomycin (STR), and tetracycline (TET). Isolates resistant to antibiotics were most often multidrug resistant. Serovars Hadar and Typhimurium were resistant to KAN, STR, and TET and GEN, SMX, and STR, respectively. All isolated Salmonella serovars were resistant to the disinfectant chlorhexidine with minimum inhibitory concentrations (MICs; 1-8 µg/mL), and they were susceptible to triclosan and benzalkonium chloride. The didecyldimethylammonium chloride component was the most active ammonium chloride tested. No cross-resistance was observed between antibiotics and disinfectants. The MICs for 3-NHPAA (4096 µg/mL) were consistent between processing Plant 1 and Plant 2, but MICs for the 3-NHPAA metabolites (As(III) and As(V)) were higher in Plant 1 than in Plant 2. In Plant 1, 76% of the isolates had MICs >256 µg/mL for As(III) and 92% of the isolates had MICs >1024 µg/mL for As(V). In Plant 2, all of the isolates had MICs ≤256 µg/mL for As(III) and 90% of the isolates had MICs ≤1024 µg/mL for As(V). Only 4 Salmonella serovars were isolated from Plant 1, but 10 serovars were isolated from Plant 2. S. enterica serovar Derby from Plant 1 was highly resistant to As(III) and As(V) with MICs >1024 and >8192 µg/mL, respectively, suggesting previous exposure to high arsenic metabolite concentrations. These levels may have been high enough to kill other Salmonella serovars, thus possibly explaining the lack of serovar diversity observed in Plant 1. The application of a growth promoter may affect the serovar diversity in treated birds.

Dietary Fat Chain Length, Saturation, and PUFA Source Acutely Affect Diet-Induced Thermogenesis but Not Satiety in Adults in a Randomized, Crossover Trial.

Structural differences in dietary fatty acids modify their rate of oxidation and effect on satiety, endpoints that may influence the development of obesity. This study tests the hypothesis that meals containing fat sources with elevated unsaturated fats will result in greater postprandial energy expenditure, fat oxidation, and satiety than meals containing fats with greater saturation. In a randomized, 5-way crossover design, healthy men and women (n = 23; age: 25.7 ± 6.6 years; BMI: 27.7 ± 3.8 kg/m2) consumed liquid meals containing 30 g of fat from heavy cream (HC), olive oil (OO), sunflower oil (SFO), flaxseed oil (FSO), and fish oil (FO). Energy expenditure and diet-induced thermogenesis (DIT) were determined by metabolic rate over a 240 min postprandial period. Serum concentrations of ghrelin, glucose, insulin, and triacylglycerol (TAG) were assessed. DIT induced by SFO was 5% lower than HC and FO (p = 0.04). Energy expenditure and substrate oxidation did not differ between fat sources. Postprandial TAG concentrations were significantly affected by fat source (p = 0.0001). Varying fat sources by the degree of saturation and PUFA type modified DIT but not satiety responses in normal to obese adult men and women.

Four chromosome scale genomes and a pan-genome annotation to accelerate pecan tree breeding.

Genome-enabled biotechnologies have the potential to accelerate breeding efforts in long-lived perennial crop species. Despite the transformative potential of molecular tools in pecan and other outcrossing tree species, highly heterozygous genomes, significant presence-absence gene content variation, and histories of interspecific hybridization have constrained breeding efforts. To overcome these challenges, here, we present diploid genome assemblies and annotations of four outbred pecan genotypes, including a PacBio HiFi chromosome-scale assembly of both haplotypes of the 'Pawnee' cultivar. Comparative analysis and pan-genome integration reveal substantial and likely adaptive interspecific genomic introgressions, including an over-retained haplotype introgressed from bitternut hickory into pecan breeding pedigrees. Further, by leveraging our pan-genome presence-absence and functional annotation database among genomes and within the two outbred haplotypes of the 'Lakota' genome, we identify candidate genes for pest and pathogen resistance. Combined, these analyses and resources highlight significant progress towards functional and quantitative genomics in highly diverse and outbred crops.

Development and evaluation of WillTry. An instrument for measuring children's willingness to try fruits and vegetables.

This paper describes the development and evaluation of the WillTry instrument, a psychometric tool designed to measure children's willingness to try fruits and vegetables. WillTry surveys were interviewer-administered to 284 children in an elementary school and summer day camps located in rural Mississippi and Arkansas (United States) communities. Factor analysis was used to determine construct dimensionality. Additional evaluation included internal consistency, test-retest reliability, and predictive validity. Factor analysis suggested a single dimension for the food items. The WillTry food scale had substantial reliability (intraclass correlation coefficients between 0.61 and 0.80) and sufficient internal consistency (Cronbach's alpha > or = 0.70). Results of the regression analysis for percent consumption of foods offered on WillTry response confirmed the predictive validity of the instrument. The results of these analyses provide psychometric evidence for the use of the WillTry instrument as a measure of willingness to try fruits and vegetables in rural, southern US children 5-14 years of age.

Effect of racemic, (+)- and (-)-gossypol on survival and development of Heliothis virescens larvae.

Gossypol is a constituent of the lysigenous foliar glands of cotton plants and is also found in glands in cottonseed. Gossypol exists as enantiomers because of restricted rotation around the binaphthyl bond. The biological activities of the enantiomers differ. For example, (+)-gossypol can be fed safely to nonruminants such as chickens, but (-)-gossypol cannot. Most commercial cottonseed contain a (+)- to (-)-gossypol ratio of approximately 3:2. Conventional breeding techniques can be used to develop cottonseed that contains >95% (+)-gossypol. Notably, gossypol protects the plant from insect herbivores. Herein, we report the effect of various forms of gossypol on Heliothis virescens (Fabricius) larvae. Three levels (0.16, 0.24, and 0.32%) of racemic, (+)-, and (-)-gossypol were added to artificial rearing diets and were fed to H. virescens larvae. All 0.24 and 0.32% gossypol diets significantly lengthened days-to-pupation and decreased pupal weight compared with the control. Percent survival was significantly less for larvae reared on diets containing 0.24% of all three forms of gossypol as compared with the control diet. (+)-Gossypol was superior or equivalent to racemic gossypol as measured by the three parameters studied. Higher concentrations of all gossypol forms were required to reduce survival and pupal weights and increase days-to-pupation for larvae of H. virescens larvae compared with the concentration needed to affect larvae of Helicoverpa zea (Boddie), which was studied previously. These results indicate that current efforts to breed cotton lines containing mostly (+)-gossypol in seed should not significantly impair the plant's natural defenses against insects.

Differences in Active Defense Responses of Two Gossypium barbadense L. Cultivars Resistant to Fusarium oxysporum f. sp. vasinfectum Race 4.

A highly virulent race 4 genotype of Fusarium oxysporum f. sp. vasinfectum (Fov) was identified for the first time in the western hemisphere in 2002 in cotton fields in the San Joaquin Valley of California. The Gossypium barbadense L. cotton cultivars 'Seabrook Sea Island 12B2' ('SBSI') and 'Pima S-6' are resistant to Fov race 4. Active defense responses were quantitated by monitoring the accumulation of antimicrobial terpenoids (i.e., phytoalexins) in inoculated stem stele tissue in these cultivars. The increase in the concentration of the most toxic phytoalexins was statistically faster after 24 h in 'SBSI' compared to 'Pima S-6'. The sesquiterpenoid hemigossylic acid lactone, which was observed for the first time in nature, also accumulated in diseased plants. Neither hemigossylic acid lactone nor the disesquiterpenoids gossypol, gossypol-6-methyl ether, and gossypol-6,6'-dimethyl ether showed toxicity to Fov. Segregation of F2 progeny from 'SBSI' × 'Pima S-6' crosses gave a few highly susceptible plants and a few highly resistant plants, indicating separate genes for resistance in the two cultivars.

Interactions of organic acids with Campylobacter coli from swine.

Campylobacter coli is a bacterial species that is a major cause of diarrheal disease worldwide, and Campylobacter spp. are among the top 5 foodborne pathogens in the United States. During food production organic acids (OAs) are often used to remove bacteria from animal carcasses. The interactions of six OAs with 111 C. coli strains obtained from swine and retail pork chops were studied by determining the molar minimum inhibitory concentrations (MICMs) of the C. coli strains, and the pH at the MICMs. The Henderson-Hasselbalch equation was used to calculate the concentrations of the undissociated and dissociated OAs at the MICMs of the C. coli strains. The results for the 111 different C. coli strains obtained from different locations were treated as a single group for each OA since many of the C. coli strains behaved similarly to each different OA. Inhibition of C. coli was not dependent on pH or on the undissociated OA species, but C. coli inhibition correlated with the dissociated OA species. Therefore, if the concentration of the dissociated OAs decreases from optimum, one may then expect that C. coli bacteria would escape disinfection. The concentration of the dissociated OA should be carefully controlled in a carcass wash. We suggest maintaining a concentration of the dissociated acetic, butyric, citric, formic, lactic and propionic acids at 29, 23, 11, 35, 22 and 25 mM, respectively, when using a carcass wash with these OAs to remove C. coli bacteria. However, due to C. coli utilization of acetate, formate, lactate and propionate, these four OAs may not be the best choice to use for a carcass wash to remove C. coli contamination. Of the six OAs, citric acid was the most efficient at inhibiting C. coli.

Regional patterns in foliar (15)N across a gradient of nitrogen deposition in the northeastern US.

Recent studies have demonstrated that natural abundance (15)N can be a useful tool for assessing nitrogen saturation, because as nitrification and nitrate loss increase, delta(15)N of foliage and soil also increases. We measured foliar delta(15)N at 11 high-elevation spruce-fir stands along an N deposition gradient in 1987-1988 and at seven paired northern hardwood and spruce-fir stands in 1999. In 1999, foliar delta(15)N increased from -5.2 to -0.7 per thousand with increasing N deposition from Maine to NY. Foliar delta(15)N decreased between 1987-1988 and 1999, while foliar %N increased and foliar C:N decreased at most sites. Foliar delta(15)N was strongly correlated with N deposition, and was also positively correlated with net nitrification potential and negatively correlated with soil C:N ratio. Although the increase in foliar %N is consistent with a progression towards N saturation, other results of this study suggest that, in 1999, these stands were further from N saturation than in 1987-1988.

Detoxification of Fusaric Acid by the Soil Microbe Mucor rouxii.

Fusarium oxysporum f. sp. vasinfectum race 4 (VCG0114), which causes root rot and wilt of cotton (Gossypium hirsutum and G. barbadense), has been identified recently for the first time in the western hemisphere in certain fields in the San Joaquin Valley of California. This pathotype produces copious quantities of the plant toxin fusaric acid (5-butyl-2-pyridinecarboxylic acid) compared to other isolates of F. oxysporum f. sp. vasinfectum (Fov) that are indigenous to the United States. Fusaric acid is toxic to cotton plants and may help the pathogen compete with other microbes in the soil. We found that a laboratory strain of the fungus Mucor rouxii converts fusaric acid into a newly identified compound, 8-hydroxyfusaric acid. The latter compound is significantly less phytotoxic to cotton than the parent compound. On the basis of bioassays of hydroxylated analogues of fusaric acid, hydroxylation of the butyl side chain of fusaric acid may affect a general detoxification of fusaric acid. Genes that control this hydroxylation may be useful in developing biocontrol agents to manage Fov.

Genetic architecture of cold tolerance in rice (Oryza sativa) determined through high resolution genome-wide analysis.

Cold temperature is an important abiotic stress which negatively affects morphological development and seed production in rice (Oryza sativa L.). At the seedling stage, cold stress causes poor germination, seedling injury and poor stand establishment; and at the reproductive stage cold decreases seed yield. The Rice Diversity Panel 1 (RDP1) is a global collection of over 400 O. sativa accessions representing the five major subpopulations from the INDICA and JAPONICA varietal groups, with a genotypic dataset consisting of 700,000 SNP markers. The objectives of this study were to evaluate the RDP1 accessions for the complex, quantitatively inherited cold tolerance traits at the germination and reproductive stages, and to conduct genome-wide association (GWA) mapping to identify SNPs and candidate genes associated with cold stress at these stages. GWA mapping of the germination index (calculated as percent germination in cold divided by warm treatment) revealed 42 quantitative trait loci (QTLs) associated with cold tolerance at the seedling stage, including 18 in the panel as a whole, seven in temperate japonica, six in tropical japonica, 14 in JAPONICA, and nine in INDICA, with five shared across all subpopulations. Twenty-two of these QTLs co-localized with 32 previously reported cold tolerance QTLs. GWA mapping of cold tolerance at the reproductive stage detected 29 QTLs, including seven associated with percent sterility, ten with seed weight per panicle, 14 with seed weight per plant and one region overlapping for two traits. Fifteen co-localized with previously reported QTLs for cold tolerance or yield components. Candidate gene ontology searches revealed these QTLs were associated with significant enrichment for genes related to with lipid metabolism, response to stimuli, response to biotic stimuli (suggesting cross-talk between biotic and abiotic stresses), and oxygen binding. Overall the JAPONICA accessions were more tolerant to cold stress than INDICA accessions.

Gossypolhemiquinone, a dimeric sesquiterpenoid identified in cotton (Gossypium).

The report that the cotton leaf perforator, Bucculatrix thurberiella, is one of the few insect herbivores to attack Gossypium thurberi prompted an investigation of the terpenoids present in the leaves of this wild species of cotton. Members of Gossypium produce subepidermal pigment glands in their leaves that contain the dimeric sesquiterpenoid gossypol as well as other biosynthetically related terpenoids. In addition to gossypol, a previously unknown dimeric sesquiterpenoid, gossypolhemiquinone (GHQ), was identified in trace amounts in G. thurberi, a member of the D genome. Other members of the D genome of Gossypium were subsequently found to contain this compound, but GHQ was not detected in commercial cotton cultivars. When fed to Helicoverpa zea in an artificial diet, GHQ delayed days-to-pupation, reduced pupal weights, and survival to adulthood to a lesser or equal extent than gossypol in comparison to the control diet. However, GHQ had a synergistic effect on survival and days-to-pupation when combined with gossypol at the highest dosage tested (0.18%; 15.5:84.5 GHQ:gossypol). Because gossypol exhibits anti-cancer activity, GHQ was also evaluated for its anti-cancer activity against the National Cancer Institute's 60-Human Tumor Cell Line Screen. Significant inhibitory activity against most of these cell lines was not observed, but the results may offer some promise against leukemia cancer cell lines.