Deoxynivalenol (DON) is a mycotoxin found in cereal grains and cereal-based foods. DON concentrations in finished products are reduced under some processing conditions, but not others. DON concentrations in flour, wheat and selected foods made from them under commercially relevant conditions were compared by GC with electron capture detection. Average concentrations (n = 9/item) in cookies, crackers and pretzels ranged from 61% (cookies) to 111% (pretzels) compared with flour (100% = 0.46 mu g g-1). Lesser amounts were found in donuts and bread: their respective DON concentrations were 44% and 30% that of flour. Mass balance estimates for DON (mu g g-1 flour equivalents) ranged from 50% (bread = 0.23 mu g g-1 flour equivalents) to 120% (donuts), indicating that dilution by recipe ingredients contributed to DON reductions in bread and accounted for all of the apparent reduction in donuts. Mass balance estimates averaged 76% (crackers) to 107% (pretzels) for the other flour products. DON concentrations were higher in cereal flakes (0.55 mu g g-1 in the finished product and 0.58 mu g g-1 on a mass balance basis) than in wheat (0.40 mu g g-1), suggesting that DON concentrations might increase during processing of wheat cereals under some conditions. In summary, DON concentrations of finished food products were reduced epsilon 50% only in bread and donuts. Reduction in bread resulted from a combination of DON 'loss' and dilution by recipe ingredients whereas the reduction in donuts was due entirely to dilution. These results are further evidence of DON stability during the preparation of popular flour or wheat-based products.

ABSTRACT Neotyphodium coenophialum, an endophytic fungus associated with tall fescue grass, enhances host fitness and imparts pest resistance. This symbiotum is implicated in the reduction of stresses, including plant-parasitic nematodes. To substantiate this implication, toxicological effects of root extracts, polyphenolic fraction, ergot, and loline alkaloids from endophyte-infected tall fescue were investigated using Pratylenchus scribneri, a nematode pest of tall fescue. In vitro bioassays and greenhouse studies were used as tests for effects of root fractions and compounds on motility and mortality of this lesion nematode. Greenhouse studies revealed that endophyte-infected tall fescue grasses are essentially nonhosts to P. scribneri, with root populations averaging 3 to 17 nematodes/pot, compared with 4,866 and 8,450 nematodes/pot for noninfected grasses. The in vitro assay indicated that root extracts from infected tall fescues were nematistatic. Polyphenols identified in extracts included chlorogenic acid, 3,5-dicaffeoylquinic acids, caffeic acid, and two unidentified compounds, but these were not correlated with endophyte status, qualitatively or quantitatively. Tests of several ergot alkaloids revealed that ergovaline and alpha-ergocryptine were nematicidal at 5 and 50 microg/ml, respectively, while ergocornine and ergonovine were nematistatic at most concentrations. Loline (N-formylloline), the pyrrolizidine alkaloid tested, was nematicidal (50 to 200 microg/ml). The ecological benefits of the metabolites tested here should assist in defining their role in deterring this nematode species while offering some probable mechanisms of action against plant-parasitic nematodes in general.

Knowledge of the inheritance of C-glycosyl flavone synthesis in maize (Zea mays L.) silk tissues has been acquired through detailed genetic studies involving primarily germplasm from the Corn Belt Dent race. To test the robustness of this genetic knowledge, we examined C-glycosyl flavone synthesis in a genetically distinct germplasm pool, popcorn. C-glycosyl flavone profiles and levels and the involvement of three specific genes/quantitative trait loci (p, pr1, and sm1) in C-glycosyl flavone synthesis were examined in popcorn germplasm representing at least two races and various diverse geographic regions. Twenty-four inbred lines and 23 hybrids involving these inbred lines and inbred line R17 were characterized for their flavone profiles and levels in silk tissues. Two F2 mapping populations were constructed to examine the involvement of p, pr1, and sm1 on C-glycosyl flavone synthesis. C-glycosyl flavone levels threefold higher than previously reported in Corn Dent Belt materials and a novel class of compounds were discovered. The gene action of sm1 was different, the functional p allele was not always dominant, and pr1 did not affect mays in synthesis. Based on this rather simplistic "model" quantitative trait, it appears that caution should be exercised when attempting to apply quantitative trait locus knowledge accumulated in one germplasm base to a germplasm base that is known to be distinctly unique.

The toxic potential of nixtamalized foods can be underestimated if, during cooking, reversible fumonisin-food matrix interactions reduce the amount of mycotoxin that is detected but not the amount that is bioavailable. Fusarium verticillioides culture material (CM) was nixtamalized as is (NCM) or after mixing with ground corn (NCMC). Additional portions were sham nixtamalized without (SCM) or with corn (SCMC). Nixtamalization and sham nixtamalization reduced FB(1); CM, NCM, and SCM diets contained 9.08, 2.08, and 1.19 ppm, respectively. FB(1) was further reduced in the NCMC (0.49 ppm) but not the SCMC (1.01 ppm) diets compared to their NCM and SCM counterparts. Equivalent weights of the cooked products, uncooked CM, corn (UC) or nixtamalized UC (NUC) were fed to rats for up to three weeks. Kidney lesions in the NCM-fed group were less severe than in the CM-fed, positive control group and no lesions were found in the NCMC and other groups. Group kidney sphinganine (biomarker of fumonisin exposure) concentrations decreased in the order: CM (absolute concentration (nmol/g)=600-800)>NCM (400-600)>SCM and SCMC (30-90)>NCMC, UC and NUC (<8). Together, these results suggest that mycotoxin-corn matrix interactions during nixtamalization reduce the bioavailability and toxicity of FB(1).

Leaf tissue collected from six zoysiagrass (Zoysia spp.) cultivars was analyzed for polyphenols and flavonoids by high performance liquid chromatography (HPLC). The experiment investigated the effects of sampling date and N fertilization rate on green leaf chemistry of zoysiagrass and their relationship to fall armyworm (FAW) [Spodoptera frugiperda (J. E. Smith)] resistance. Six zoysiagrasses cultivars {>Crowne= (Z. japonica Steud.), >Palisades= (Z. japonica Steud.), >El Toro= (Z. japonica Steud.), >Meyer= (Z. japonica Steud.), >Cavalier= [Z. matrella (L.) Merr.], and 'Emerald' (Z. japonica Stued. × Z. tenuifolia Willd. ex Trin.)} were planted in a randomized split-plot design with 4 replicates using cultivars as the main plot and 12.2 and 48.9 kg of N ha month [(NH4)2SO4] as the split plots. Flavonoid concentration decreased as the amount of applied N increased. Flavonoid concentration was greatest in June and steadily declined throughout July and August. Two unidentified flavonoids (luteolin-glycosides) were consistently associated with FAW mortality when analyzed by stepwise regression techniques. Unidentified luteolin 3 had an inverse relationship with mortality, while unidentified luteolin 9 was positively correlated with mortality. Additional research is needed to determine if the concentration of luteolins found in resistant zoysiagrasses are sufficient to cause biocidal activity in FAW. INTRODUCTION The fall armyworm (FAW) [Spodoptera frugiperda (J. E. Smith)] is a major pest of turfgrasses in the Americas and the Caribbean Basin. This pest is particularly damaging on turf in large contiguous areas such as pastures, sod farms, recreational parks and on golf courses. Larvae feed on above ground plant parts moving in mass across the landscape. Most established warm-season grasses will recover from FAW damage if properly cared for after an infestation. However, newly established turf is particularly susceptible to FAW damage due to its limited root system and carbohydrate reserves. Some cool-season grasses, including bluegrasses and fescues, can be permanently damaged if the meristematic region of the plant is consumed (Brandenburg and Villani, 1995). Many genotypes of turf and forage grasses have been reported to have varying levels of resistance to FAW as summarized by Reinert et al. (2004). Resistance to FAW in bermudagrass, (Cynodon dactylon Pers. var. ‘Tifton 292’), was first reported by Leuck Proc. II IC on Turfgrass Eds.: J.C. Stier et al. Acta Hort. 783, ISHS 2008 508 et al. (1968). Tifton 292 was reported to have high levels of non-preference and antibiosis to FAW (Lynch et al., 1983; Chang et al., 1985a). Chang et al. (1985b) reported wing pad deformities in FAW pupae and/or serious lesions in adult wings when Tifton 292 bermudagrass leaf extracts were incorporated into diet mixtures and fed to neonate FAW larvae. However, Jamjanya and Quisenberry (1988) found only moderate resistance in Tifton 292. Leuck and Skinner (1970) reported that mortality of FAW was greater on Georgia accession No. 239 bermudagrass than on >Coastal= bermudagrass. Resistance to FAW has also been documented in ‘Common’ centipedegrass [Eremochloa ophiuroides (Munro) Hackel] (Wiseman et al., 1982). Chang et al. (1985a) reported that the order of preference of FAW larvae for six grasses tested was ‘Tifton 10’ bermudagrass > Coastal bermudagrass > common centipedegrass > ‘C-181’ centipedegrass > Tifton 292 bermudagrass > zoysiagrass (no cultivars identified). In no-choice feeding experiments, Reinert (1994, 1997, 1998) determined that FAW larvae had higher mortality levels when fed excised leaf tissue of zoysiagrasses (Zoysia spp.) cultivars, ‘Cavalier’, ‘Meyer’, ‘El Toro’ and ‘Emerald’ compared to ‘Crowne’ and ‘Palisades’. Plants produce a wide array of naturally occurring chemicals that are believed to provide defense against herbivore and pathogen attack. Two groups of these naturally occurring chemicals that have been shown to have biocidal properties against FAW in laboratory bioassays are caffeic acid derivatives, primarily chlorogenic acid, and flavonoids such as maysin, luteolin, rutin and isoorientin. Research studies conducted on the interaction of these chemicals and insect biology vary in their results. Chlorogenic acid and flavonoid-glycosides added to diet media reduce FAW larval weights and increase FAW mortality in laboratory bioassay (Wiseman et al., 1982, 1992; Johnson et al., 2002). Wiseman et al. (1990) reported that chlorogenic acid, maysin and other luteolin-glycosides are the major factors for the antibiotic resistance of centipedegrass to FAW. Silks of Zapalote Chico, an exotic corn cultivar, contain high levels of maysin that severely reduced corn earworm [Helicoverpa zea (Boddie)] larval growth and development (Waiss et al., 1979). Maysin and other luteolins were reported to be responsible for resistance of teosinte, an ancestor of corn, to FAW (Gueldner, 1991). Cole (1984) reported that high levels of isochlorogenic acid in lettuce (Lactuca sativa L.) increased resistance to the root aphid [Pemphigus bursarius (L.)]. Johnson and Severson (1989) reported that the weights of larvae of the tobacco budworm [Heliothis virescens (F.)] were depressed by chlorogenic acid. However, Lindroth and Peterson (1988) reported that chlorogenic acid had no effect on southern armyworm [Spodoptera eridania (Cramer)]. The purpose of our study was to determine if previously observed variability in FAW resistance was associated with the concentrations of polyphenol and flavonoid in the zoysiagrass cultivars. Secondly, we wanted to determine the impact of N fertilization on the concentration of polyphenols and flavonoids in these cultivars. MATERIALS AND METHODS Plant Material The study was conducted at the Texas A&M University Field Laboratory, College Station, TX on a fine, montmorillontic, thermic Vertic Albaqualfs. Six zoysiagrasses cultivars {>Crowne= (Z. japonica Steud.), >Palisades= (Z. japonica Steud.), >El Toro= (Z. japonica Steud.), >Meyer= (Z. japonica Steud.), >Cavalier= [Z. matrella (L.) Merr.], and 'Emerald' (Z. japonica Stued. × Z. tenuifolia Willd. ex Trin.} were planted by sprigging on 7 May 1996 in a randomized split-plot design with 4 replicates using cultivars as the main plot and N treatments as the split plots. Grasses were grown for about 2 years prior to the initial tissue sampling for this study. Whole plots were 3.6 m wide and 5.5 m in length. N was applied as (NH4)2SO4 at 12.2 and 48.9 kg of N ha month to the respective split plots during the growing season beginning at planting and continuing throughout the duration of the experiment. The plots were irrigated twice each week during the growing season to replace 70% of evaporation from a Class A Pan to prevent

Resin glycosides are complex compounds composed primarily of fatty acids and sugars that contribute to the allelopathic potential and pest resistance of sweetpotato. Total periderm resin glycoside (PRG) contents of 10 sweetpotato (Ipomoea batatas L.) clones grown in field trials were determined using high pressure liquid chromatography (HPLC). PRG contents of the clones ranged from 0.04 to 10.02 % of periderm dry weight. Analysis of variance indicated that genotype accounted for most of the variation, however, when PRG contents from the three trials were combined and analyzed using a factorial design, environment and the genotype x environment interaction variances were also highly significant. Average PRG contents of progeny from a cross between a high PRG clone (Excel) and a low PRG clone (SC 1149-19) were 4.13 and 4.21 % periderm dry weight for the two maternal parents, respectively. PRG contents of individual progeny clones ranged from 0.1 to more than 20 % of periderm dry weight, and the distribution of contents among progeny was similar for the two maternal parents. These observations indicate that breeding sweetpotato genotypes with high PRG is possible and may be an effective way of enhancing allelopathic potential and pest resistance.

Biotypes of the Neotyphodium coenophialum-tall fescue grass symbiota are provided with enhanced protection from grazing vertebrate herbivores due to the production of toxic secondary metabolites. However, considerable controversy exists concerning this symbiotum and its toxicity to nematode species. A sterile in vitro system was developed to determine the interactive nature of known toxins specific to this mutualistic association and compounds within grass extracts known to be nematotoxic. The in vitro assay used Pratylenchus scribneri, the lesion nematode, as the target organism to determine the interactive nature of ergot alkaloids, the pyrrolizidine alkaloid (the lolines), total phenolic fractions, and specific phenolic compounds. The in vitro assay is described along with methods for testing toxicity. The results indicate that only two of three ergot alkaloids were toxic to P. scribneri, and there were possible potentiating or synergistic effects with other alkaloids and water soluble polyphenolics. HPLC analysis and UV mass spectrometry of root extracts revealed the presence of two major polyphenolics, chlorogenic and di-caffeoylquinic acids, both of which are natural constituents of this and other plants and have known toxicity to several species of nematodes. Further, it was determined that there were quantitative differences between the total phenolic and specific phenolic contents in roots of endophyte infected and noninfected tall fescue, cultivar Jesup. This in vitro assay offers a rapid and routine screen for acute testing chemical components of the tall fescue-endophyte symbiotum for toxicity to this nematode species. Keywords: Chlorogenic acid, di-caffeoylquinic acids, ergot alkaloid, lolines, nematode, polyphenolics, Pratylenchus scribneri, pyrrolizidine alkaloid

Field trials using Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) and Euxesta stigmatias Loew (Diptera: Ulidiidae) were conducted to evaluate resistance and potential damage interactions between these two primary corn, Zea mays L., pests against Lepidoptera-resistant corn varieties derived from both endogenous and exogenous sources. The endogenous source of resistance was maysin, a C-glycosyl flavone produced in high concentrations in varieties 'Zapalote Chico 2451' and 'Zapalote Chico sh2'. The exogenous resistance source was the Bacillus thuringiensis (Bt)11 gene that expresses Cry1A(b) insecticidal protein found in 'Attribute GSS-0966'. Damage by the two pests was compared among these resistant varieties and the susceptible 'Primetime'. Single-species tests determined that the Zapalote Chico varieties and GSS-0966 effectively reduced S. frugiperda larval damage compared with Primetime. E. stigmatias larval damage was less in the Zapalote Chico varieties than the other varieties in single-species tests. E. stigmatias damage was greater on S. frugiperda-infested versus S. frugiperda-excluded ears. Ears with S. frugiperda damage to husk, silk and kernels had greater E. stigmatias damage than ears with less S. frugiperda damage. Reversed phase high-performance liquid chromatography analysis of nonpollinated corn silk collected from field plots determined that isoorientin, maysin, and apimaysin plus 3'-methoxymaysin concentrations followed the order Zapalote Chico sh2 > Zapalote Chico 2451 > Attribute GSS-0966 = Primetime. Chlorogenic acid concentrations were greatest in Zapalote Chico 2451. The two high maysin Zapalote Chico varieties did as well against fall armyworm as the Bt-enhanced GSS-0966, and they outperformed GSS-0966 against E. stigmatias.

Maysin is a naturally occurring C-glycosyl flavone found in maize (Zea mays L.) silk tissue that confers resistance to corn earworm (Helicoverpa zea, Boddie). Recently, two new maize populations were derived for high silk maysin. The two populations were named the exotic populations of maize (EPM) and the southern inbreds of maize (SIM). Quantitative trait locus (QTL) analysis was employed to determine which loci were responsible for elevated maysin levels in inbred lines derived from the EPM and SIM populations. The candidate genes consistent with QTL position included the p (pericarp color), c2 (colorless2), whp1 (white pollen1) and in1 (intensifier1) loci. The role of these loci in controlling high maysin levels in silks was tested by expression analysis and use of the loci as genetic markers onto the QTL populations. These studies support p, c2 and whp1, but not in1, as loci controlling maysin. Through this study, we determined that the p locus regulates whp1 transcription and that increased maysin in these inbred lines was primarily due to alleles at both structural and regulatory loci promoting increased flux through the flavone pathway by increasing chalcone synthase activity.

Two compounds, the C-glycosyl flavone maysin and the phenylpropanoid product chlorogenic acid (CGA), have been implicated in corn earworm (Helicoverpa zea Boddie) resistance in maize (Zea mays L.). Previous quantitative trait locus (QTL) analyses identified the pericarp color (p) locus, which encodes a transcription factor, as the major QTL for maysin and CGA. QTL analysis has also implicated the dihydroflavanol reductase (DFR; E.C. no. 1.1.1.219) locus anthocyaninless1 (a1) and the duplicate chalcone synthase (CHS; E.C. no. 2.3.1.74) loci colorless2 (c2) and white pollen1 (whp1) as genes underlying QTL for maysin and/or CGA synthesis. Epistatic interactions between p and a1 and between p and c2 were also defined. CHS catalyzes the first step in the flavonoid pathway and represents one of the first enzyme steps following the branch off the general phenylpropanoid pathway towards CGA synthesis. In maize, the reduction of dihydroflavanol to leucoanthocyanin by DFR immediately follows the pathway branch leading to C-glycosyl flavone production. The detection of QTLs for maysin and CGA concentration at loci encoding enzyme steps following the pathway branch points implicates alterations in the flow of biochemical intermediates as the biological basis of the QTL effects. To examine if sequence variation among alleles of a1, c2, and whp1 affect maysin and CGA synthesis in maize silks, we performed an association analysis. Because the p locus has often been a major QTL for maysin and CGA and has exhibited epistatic interactions with a1, c2, and whp1, association analysis was conditioned on the p genotype. A highly significant association of two sequence polymorphisms in the promoter of a1 with maysin synthesis was demonstrated. Additional conditioning on the genotype of the significant a1 polymorphism allowed the detection of a significant polymorphism within the whp1 promoter. Our analyses demonstrate that conditioning for epistatic factors greatly increases the power of association testing.

Two maize (Zea mays L.) breeding populations with very high concentrations of maysin, a silk-expressed flavone glycoside, were tested for their ability to resist ear damage by the corn earworm, Helicoverpa zea Boddie, under field conditions. Tests were conducted in 2000 and 2001 at multiple locations in Georgia. The high maysin populations, EPM6 and SIM6, as well as resistant and susceptible checks, were scored for silk-maysin content, H. zea damage, and husk characters. In 2000, there was a negative correlation between husk tightness and earworm damage at three of five locations, while there was no significant correlation between damage and maysin content at any location. In 2001, EPM6 and SIM6 had approximately ten times the maysin content of the low-maysin control genotypes; nevertheless, earworm damage to EPM6 and SIM6 was either greater than or not significantly different from the low-maysin genotypes at all locations. The resistant control genotype, Zapalote Chico, had significantly less earworm damage than EPM6 and SIM6 for both years at all locations. The results of this study highlight the importance of identifying and quantifying husk and ear traits that are essential to H. zea resistance in maize.