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A semiselective, diagnostic agar medium (T-5) and low temperature incubation technique were developed for recovering Pseudomonas viridiflava from the environment or plant material. Medium T-5 contains the following per liter: NaCl, 5.0 g; NH4H2PO4, 1.0 g; K2HPO4, 1.0 g; MgSO4·H2O, 0.2 g; D-tartaric acid, 3.0 g; phenol red, 0.01 g; agar, 20.0 g; bacitracin, 10 mg; vancomycin, 6 mg; cycloheximide, 75 mg; novobiocin, 45 mg; penicillin G, 5 mg. The pH is adjusted to 7.4. Antibiotics are added aseptically after autoclaving. P. viridiflava recovery from artificially infested, field-soil (Tifton loamy-sand), with a cropping history of no onion production, was high, with a corresponding reduction of 99.99% of nontarget bacteria. However, soils from fields with a long history of onion production, near Vidalia, Georgia, contained significantly larger populations of background microflora that grew on medium T-5. Incubation at 5°C reduced contaminating microflora 1,000- to 10,000-fold with no reduction in recovery of the target organism. However, this low temperature incubation required an increased incubation period of 3 weeks and reduced the level of fluorescence of P. viridiflava.

Identifying effective weed control regimes for organic peanut is paramount for improving the feasibility of organic production. Tine cultivation is a proven effective method for reducing in-row weed populations in several crops. Field trials were therefore conducted in 2008 and 2009 to assess the effects of tine cultivation combined with sweep cultivation and supplemental hand-weeding on weed control and overall productivity of two peanut cultivars under organic management. Tine cultivation regimes consisted of two frequencies (once per week or twice per week) for three durations (3 wk, 4 wk, or 5 wk). All cultivation treatments were also cultivated with flat sweeps at least once and hand-weeded periodically during the growing season. A non-cultivated, non-weeded control was included for comparison. All cultivation treatments significantly reduced annual grass populations in 2008 and Florida pusley populations both years. Cultivated treatments also resulted in denser plant stands for peanut (9.2 plants/m to 13.2 plants/m) than the non-cultivated control (5.9 plants/m to 7.9 plants/m). Pod yields in cultivated treatments ranged from 3502 kg/ha to 3823 kg/ha and were all significantly greater than yields in the non-cultivated control (1630 kg/ha). Also, net revenues generated by cultivated treatments ranged from ($3333/ha to $3637/ha) and were greater than that of the control ($1795/ha). Cultivation frequency had little effect on weed control and peanut productivity. However, the 4- and 5-wk durations displayed potential for improving peanut yield, grade, and net revenue over the 3-wk duration, especially when annual grass weeds were predominant. Cultivating once weekly for 4 or 5 wk with a tine cultivator, along with at least one sweep cultivation and supplemental hand-weeding, is a viable, economical option for providing adequate weed control and maximizing productivity of organically-managed peanut at current market premiums.

Experiments were conducted during 2000 and 2001 at a total of 13 locations throughout Alabama, Georgia, Florida, North Carolina, and Texas to evaluate efficacy of herbicides at or below the manufacturer's suggested use rate. Herbicide applications included diclosulam and flumioxazin applied PRE alone or followed by imazapic applied early postemergence (EPOST). All possible combinations of diclosulam at 0, 13.5, or 27 g ai/ha and flumioxazin at 0, 53, or 105 g ai/ha applied PRE were included. Imazapic was applied at 35 g ai/ha. Ivyleaf morningglory was controlled more than 87% when imazapic was applied EPOST regardless of PRE herbicide. Pitted morningglory control > 67% was observed with applications of diclosulam (27 g/ha) followed by imazapic, diclosulam (13.5 g/ha) plus flumioxazin (53 g/ha), diclosulam (13.5 g/ha) plus flumioxazin (105 g/ha), and diclosulam (27 g/ha) plus flumioxazin (105 g/ha). Sicklepod was controlled more than 74% with flumioxazin (53 g/ha) followed by imazapic and diclosulam (27 g/ha) plus flumioxazin (105 g/ha) followed by imazapic. Florida beggarweed was controlled more than 84% by all PRE herbicide combinations except flumioxazin (53 g/ha) alone or diclosulam (27 g/ha) alone or with imazapic. Yellow nutsedge was controlled at least 90% with diclosulam at either rate followed by imazapic and by diclosulam plus flumioxazin followed by imazapic regardless of rate. Pod yield was generally higher when herbicides were applied regardless of herbicide combination or rate. Peanut yield was maximized with the lowest rates of flumioxazin or diclosulam PRE followed by imazapic EPOST.

The effects of chlorimuron application timing on the development of spotted wilt disease of peanut caused by tomato spotted wilt tospovirus was studied in fifteen field trials in Georgia from 2000 through 2007. Chlorimuron at 9 g ai/ha was applied to new peanut cultivars at various intervals ranging from 60 to 105 days after emergence (DAE) under weed-free conditions. When averaged over chlorimuron application timings, AP-3, and Georgia-02C had less spotted wilt incidence than Georgia Green but only AP-3 produced yields equivalent to Georgia Green. AT-201 had significantly higher levels of spotted wilt and 44% lower yields when compared to Georgia Green. Spotted wilt incidence of Georgia-03L did not differ from Georgia Green but the yields of GA-03L were 24% lower than Georgia Green. Differential tolerance of peanut cultivars to chlorimuron was not observed. When averaged over cultivars, chlorimuron applied at 60–69 DAE, 70–79 DAE, or 90–99 DAE increased the incidence of spotted wilt by 6–9%. However, peanut yields were not reduced by any application of chlorimuron.

A series of replicated field experiments was conducted with vegetable soybean (edamame), Glycine max (L.) Merrill, to assess the impacts of cultivars, planting dates, and insecticidal controls on insect pest abundance, crop damage and yield potential. The velvetbean caterpillar, Anticarsia gemmatalis Hübner, was the most common lepidopteran defoliator in this study, causing heavy defoliation in some years when left untreated. Other lepidopterans observed included the soybean looper, Pseudoplusia includens (Walker), and the green cloverworm, Hypena scabra (F.). Stink bugs, primarily the southern green stink bug, Nezara viridula (L.), also caused seed damage in some cultivars when left untreated. Stink bug damage exceeded expectations on edamame seeds when exposed to moderate stink bug densities (≤3 bugs per 25 sweeps). Other arthropods that were commonly observed included threecornered alfalfa hoppers, Spissistilus festinus (Say), grasshoppers, Melanoplus spp., and the potato leafhopper, Empoasca fabae (Harris). Arthropod infestations on edamame were similar to reported pest problems on conventional soybeans being produced for oil and meal. Midseason applications of the insecticides diflubenzuron plus l-cyhalothrin reduced insect pest populations, percentage of arthropod-induced defoliation and percentage of seeds damaged by stink bugs, but had little effect on edamame yields. Most defoliation and seed damage occurred during R5 development when seeds were approaching full size, thus only minimal yield reductions were noted. However, seed quality of the untreated vegetable soybeans would be unacceptable for the consumer. Total fresh green yields ranged from 2343–11,895 kg ha−1, depending on year, cultivar and planting date, whereas fresh green seed yields ranged from 1208–6,119 kg ha−1. Early-maturing edamame cultivars planted in April had fewer insect pests and less damage than the cultivars planted later. Avoidance of insect pests is an important production consideration for insect management, especially critical in an organic production system. The fresh green seed yields produced during this study demonstrate that this emerging alternative crop has the potential for economic success in the southern region, assuming that the arthropod pests are effectively managed to maintain acceptable edamame quality and yield.

Field studies were conducted in various peanut growing regions of Texas and Georgia to study peanut response to flumioxazin alone or in combination with dimethenamid or metolachlor. In south Texas during 1997, flumioxazin plus metolachlor resulted in greater than 45% peanut stunt, while flumioxazin plus dimethenamid caused ≤20% peanut stunt. This stunting was attributed to cool, wet growing conditions. Peanut yields in flumioxazin plus metolachlor-treated plots were reduced 58% from peanut in the non-treated check. In 1999 and 2000, flumioxazin plus dimethenamid or metolachlor resulted in 15% or greater peanut stunt, but stunting was not constant across weather conditions or locations. In west Texas and Georgia no peanut stunting with flumioxazin was noted. At the Levelland, TX location, flumioxazin at 0.07 kg/ha plus metolachlor at 1.1 kg/ha reduced peanut yield 32% when compared with the non-treated check; while at the Pearsall, TX location, metolachlor or dimethenamid at 1.1 kg/ha, flumioxazin at 0.07 kg/ha plus dimethenamid at 1.5 kg/ha, and flumioxazin at 0.1 kg/ha plus dimethenamid at 1.1 kg/ha reduced peanut yield 24 to 48% when compared with the non-treated check. No yield reduction was noted in Georgia.

The tobacco thrips, Frankliniella fusca (Hinds), is an economic pest of flue-cured tobacco because it vectors tomato spotted wilt tospovirus. Other species of thrips are also vectors of spotted wilt in tobacco, including the western flower thrips, F. occidentalis (Pergande). This study examined the presence of thrips species on alternate plant hosts associated with the tobacco farmscape and surrounding area. Weed hosts were sampled from December through April from 1998 through 2001 to assess which plants provide suitable refuge and nutrients for thrips survival, reproduction, and spotted wilt infection. Thrips were identified to species and confirmed as potential vectors of spotted wilt by using ELISA to test for the presence of a non-structural tomato spotted wilt virus protein. Wild radish (Raphanus raphanistrum L.), broomsedge (Andropogon virginicus L.), and narrowleaf vetch (Vicia sativa L. subsp. nigra (L.) Ehrh.) are common late-winter weeds in the farmscape that harbor spotted wilt vectors. Cutleaf evening primrose, Oenethera laciniata Hill, and volunteer soybean, Glycine max(L.) Merrill, also were hosts of spotted wilt vectors in the tobacco farmscape. Numerous other weed hosts were present in the tobacco farmscape but either had no thrips collected from them or thrips were not confirmed as potential spotted wilt vectors from these host plants. Several other plants near the tobacco farmscape also were infected with spotted wilt, and three of these host plants, common chickweed (Stellaria media (L.) Cyrillo), carrot (Daucus carota L.), and flowering dogwood (Cornus florida L.) had confirmed vectors (ELISA) collected from them. Henbit (Lamium amplexicaule L.), wild radish, cutleaf evening primrose, narrowleaf vetch, carrot, curly dock (Rumex crispus L.), red sorrel (Rumex acetosella L.), and common chickweed were confirmed as positive plant hosts in this study for spotted wilt using ELISA. Frankliniella fusca appears to be the most abundant thrips vector on these alternate plant hosts and is the predominate thrips species collected on the flue-cured tobacco, Nicotiana tabacum L. However, F. occidentalis, Haplothrips graminis Hood, and Chirothrips spp. also were confirmed in this study to be potential vectors in the tobacco farmscape. Weed hosts in the farmscape appear to be influential as refuge and nutrients for vectors and an innoculant source of tomato spotted wilt virus in the flue-cured tobacco farmscape.

Imazapic, diclosulam, and flumioxazin have been registered for use in peanut since 1996. These herbicides provide substantial residual control of broadleaf weeds in peanut. A comprehensive review was conducted for these residual herbicides to determine their role in future weed control systems in peanuts. Weed control data for research from over 100 experiments conducted from 1990–2000 by Georgia, Florida, and Auburn Universities and USDA-ARS scientists were compiled. Residual herbicide systems evaluated were imazapic postemergence (POST) at 71 g ai/ha, flumioxazin preemergence (PRE) at 70, 87, and 104 g ai/ha, diclosulam preplant incorporated (PPI) and PRE at 18 and 26 g ai/ha, and paraquat plus bentazon early POST (EPOST). Other treatments included the residual herbicides used in combination with paraquat plus bentazon EPOST, for a total of 17 treatments. Regionally important weeds were selected and included: sicklepod, Florida beggarweed, purple and yellow nut-sedge, Ipomoea morningglory species, and smallflower morningglory. Sicklepod control with imazapic alone was 86% (50 tests), 73% (25 tests) with paraquat plus bentazon, and 63% or less with diclosulam and flumioxazin regardless of rate. Florida beggarweed control was 90% (29 tests) with flumioxazin (104 g/ha PRE); 78% (50 tests) with diclosulam 26 g/ha PPI; 72% (72 tests) with imazapic; and 70% (40 tests) with paraquat plus bentazon. Purple and yellow nutsedge control was 90% with imazapic. Yellow nutsedge control was 78% (18 tests) with diclosulam (26 g/ha PRE) and less than 69% with flumioxazin and paraquat plus bentazon. Paraquat plus bentazon increased weed control over residual herbicides alone.

Field trials were conducted in Georgia, North Carolina, and Texas to evaluate the effects of preplant applications of 2,4-D, dicamba, tribenuron, and tribenuron plus thifensulfuron on peanut yield. Herbicides were applied 30, 15, 7, or 0 d before planting (DBP) in conventional production systems in Georgia and Texas, and 28, 21, 14, 7, and 0 DBP in no- and strip-tillage systems in North Carolina. Amine and ester formulations of 2,4-D did not affect peanut yield at any time of application in any state. Dicamba reduced peanut yield when applied at 0 DBP in two of seven trials. Tribenuron did not affect peanut yield regardless of preplant interval. However, tribenuron plus thifensulfuron reduced yields when applied at 7 DBP in one of five trials. These data suggest that 2,4-D, tribenuron, and tribenuron plus thifensulfuron can be safely used for preplant weed control in peanut when applied 7 DBP. Dicamba should be applied a minimum of 15 DBP.

Studies were conducted from 1999 through 2001 in Georgia to develop Texas panicum management systems in strip-tillage peanut production into a killed rye cover crop. The experimental design was a split-plot with four replications. Main plots were preemergence (PRE) herbicides for annual grass control—ethalfluralin, pendimethalin, metolachlor, alachlor, dimethenamid, and a nontreated PRE control. All plots were irrigated immediately after PRE applications to activate herbicides. Subplots were postemergence (POST) graminicides applied 28 d after peanut emergence—sethoxydim, clethodim, and a nontreated POST control. POST graminicides were applied with a crop oil concentrate. None of the PRE herbicides alone adequately controlled Texas panicum in strip-till peanut production, even with optimum activation with irrigation. Sethoxydim and clethodim controlled Texas panicum at least 91%, regardless of PRE treatments. Peanut yields were greater where ethalfluralin or pendimethalin PRE were applied sequentially with a POST graminicides, compared to PRE herbicides or POST graminicides alone. This suggests that, while POST graminicides effectively control Texas panicum, the reduced efficacy of dinitroaniline herbicides is still beneficial. The additional cost of a POST graminicide needs to be factored into production budgets for strip-tillage peanut production.

Epistasis is a pervasive phenomenon in biology. Nevertheless, attempts at identifying epistatic interactions with quantitative trait loci (QTL) analyses have yielded inconsistent results. In this study, we attempt to determine the genetic control of outbreeding depression and the possible role of epistasis following a wide cross in common bean (Phaseolus vulgaris L.). A recombinant inbred population, derived from a cross between Andean and Mesoamerican common bean cultivars, was evaluated in two markedly contrasting environments. A low-density linkage map based on AFLPs was used to locate QTLs for the number of days to maturity, average daily biomass and seed yield accumulation, and harvest index. Both independently acting and digenic epistatic QTLs of similar magnitude were identified. A majority of the loci involved in these epistatic interactions did not have an independent effect. Although we did find evidence for strong epistatic control of the traits investigated, we also found, in contrast to other recent studies, that there was no evidence for a bias toward coadapted gene complexes at the level of digenic epistasis. We discuss these results in relation to the role of epistasis in the evolutionary history of the species and methodological difficulties in detecting epistasis.

Wild plant species are often adapted to more stressful environments than their cultivated relatives. Roots are critical in exploiting soil resources that enable plants to withstand environmental stresses, but they are difficult to study. Cultivated lettuce (Lactuca sativa L.) and wild L. serriola L. differ greatly in both shoot and root characteristics. Approximately 100 F2:3 families derived from an interspecific cross were evaluated in greenhouse and field experiments. In the greenhouse, root traits (taproot length, number of laterals emerging from the taproot, and biomass) and shoot biomass were measured 4 weeks after planting. In the field, plants were grown for 9 weeks (close to harvest maturity of the cultivated parent); mild drought stress was induced by withholding water for 1 week, and gravimetric moisture of soil was then determined for five depth increments between 0–100 cm. The families were genotyped using codominantly scored AFLP markers distributed throughout the genome. Composite interval mapping was used to analyze marker-trait associations. Quantitative trait loci were identified for differences between wild and cultivated lettuce for root architectural traits and water acquisition. Thirteen QTL were detected that each accounted for 28–83% of the phenotypic variation. The loci for taproot length (i.e., cm taproot length g–1 plant biomass) and the ability to extract water from deep in the soil profile co-localized in the genome. These coincident loci were identified in separate experiments. The wild L. serriola is therefore a potential source of agriculturally important alleles to optimize resource acquisition by cultivated lettuce, thereby minimizing water and fertilizer inputs and ultimately enhancing water quality.

Volunteer peanut and cutleaf eveningprimrose are part of the epidemiology of spotted wilt disease of peanut and other susceptible crops in the Southeastern U.S. Coastal Plain. Studies were conducted on the timing and frequency of fallow harrowing, integrated with applications of glyphosate or tribenuron-methyl, for control of volunteer peanut and cutleaf eveningprimrose. Spring harrowing was generally more effective in controlling volunteer peanut than fall or winter harrowing. Conversely, cutleaf eveningprimrose was controlled by sequential harrowing in the fall, winter, and spring, with single harrowing less effective. In general, spring applications of glyphosate or tribenuron-methyl were equally effective in controlling volunteer peanut and cutleaf eveningprimrose in absence of tillage.

Tall weeds in peanut fields cause losses other that yield reduction from competition by intercepting fungicides and insecticides, and interfering with harvest efficiency. Studies were conducted at Archer, FL and Tifton, GA in 1994 and 1995 to determine an effective means to selectively control tall Florida beggarweed and sicklepod late season in peanut using herbicides applied with a wickbar. Herbicides evaluated were glyphosate, paraquat, and dimethylalkylamine salt of endothall (DMAA endothall); each applied at 0, 25, 50, 75, and 100% by volume. Treatments were applied in two passes at opposite directions midseason at both locations. Glyphosate and paraquat, at concentrations as low as 25% by volume, effectively controlled Florida beggarweed and sicklepod at both locations. DMAA endothall did not adequately control Florida beggarweed or sicklepod at either location, regardless of rate. Peanut yields were not increased by weed control from any herbicide applied with a wick-bar. The only benefits from late-season Florida beggarweed and sicklepod control with a wick-bar appear to be improved fungicide deposition and more efficient mechanical harvest.

The germplasm of cultivated common bean exhibits a lower level of genetic diversity within each geographical gene pools (Mesoamerican and Andean) compared to that of the respective wild ancestors. Crosses between these two gene pools potentially provide a source of additional genetic diversity but their progenies have been characterized by phenotypic abnormalities and reduced productivity. In order to gain additional insights into this problem, we examined the segregation for performance in two recombinant inbred populations (RIPs) resulting from Mesoamerican × Andean crosses in three contrasting environments and two years. The two RIPs – ‘California Dark Red Kidney’ (of Andean origin) × ‘Yolano’ (Mesoamerican), n = 150, and A55 (Mesoamerican) × G122 (Andean), n = 67 – were grown in replicated field tests to assess the agronomic performance of each recombinant inbred line. Both populations exhibited, on average, greater days to maturity (DTM), lower biomass growth rate (above-ground dry weight/DTM), lower economic growth rate (seed yield/DTM), and lesser harvest index. In contrast with the conclusions of earlier experiments, there was no evidence from the field trials for a genetic association (due to linkage or pleiotropy) between seed weight and economic growth rate, but there may be a genetic association between seed weight and life cycle length. We compare the results of these studies with earlier experiments on inter-gene pool recombinant populations of common beans and relate our observations of diminished performance to models of speciation mechanisms.

Greenhouse studies were conducted in 1995, 1996, and 1998 to measure the effect of preplant incorporated (PPI) and preemergence (PRE) applications of ethalfluralin and pendimethalin on growth of individual peanut seedlings in pots. Herbicide rates evaluated were 0, 0.6, 1.1, and 2.2 kg ai/ha for each herbicide. Parameters measured were time of emergence, seedling height, canopy width, foliage biomass, root length, and root biomass of individual plants. PPI applications were more injurious than PRE applications for all parameters regardless of herbicide. Ethalfluralin PPI inhibited peanut seedling growth more than equivalent rates of pendimethalin PPI. However, peanut seedling responses to PRE applications of ethalfluralin and pendimethalin were generally the same.

The influences of bahiagrass, corn, and cotton in rotation with peanut and treatments with aldicarb, flutolanil, and aldicarb plus flutolanil on nematodes, thrips, diseases caused by soilborne fungal pathogens, and yield of peanut were studied for 3 yr. Peanut yields following either 1 or 2 yr of bahiagrass, corn, or cotton were higher than those of continuous peanut. Peanut yield was greatest in the aldicarb plus flutolanil treated plots (5270 kg/ha), intermediate where aldicarb (4060 kg/ha), or flutolanil (4597 kg/ha) was used without aldicarb, and least in untreated (3690 kg/ha) plots. Yield increases in response to cropping sequences and pesticide treatments resulted primarily from suppression of crop damage by Meloidogyne arenaria, Sclerotium rolfsii, Rhizoctonia solani, and Frankliniella spp. The data document the pest management benefits and yield response associated with using two widely grown agronomic crops (corn and cotton), an improved bahiagrass cultivar, and pesticide treatments in peanut production.

A semiselective agar medium (T-5) was used to sample environment and plant material as a habitat for Pseudomonas viridiflava. Soil, irrigation water, soybean foliage, and foliage from various weeds in an onion-growing area were assayed over a 5-year period. P. viridiflava was recovered only as an epiphytic resident from weed species that included cutleaf evening primrose, dandelion, common fumitory, purple cudweed, spiny sowthistle, Virginia pepperweed, and wild radish. The bacterium apparently overseasons in association with these weeds, because its presence was detected prior to, as well as during, the onion-growing season. Preliminary tests indicated that weed control may suppress bacterial streak and bulb rot levels.

Studies were conducted in 1994 and 1995 at Headland, AL, Gainesville, FL, and Tifton, GA to quantify peanut injury by ethalfluralin applied preplant incorporated (PPI) or preemergence (PRE) at 0.0, 0.6, 1.1, 2.2, and 4.5 kg ai/ha. Parameters most sensitive to ethalfluralin injury were pod biomass and yield, while time of emergence, stand, canopy width, and foliar biomass were less sensitive. Ethalfluralin was generally more injurious when applied PPI than PRE, especially when rates were ≥ 2.2 kg/ha. At these rates, pod formation was inhibited and yields were reduced with little corresponding effect on vegetative growth. These data show ethalfluralin can be safely applied either PPI or PRE to peanut at rates ≤ 1.1 kg/ha.

B. G. Mullinix, Jr. Coastal Plain Experiment Station, Tifton, GA 37193-0748 Studies were conducted from 1990 through 1994 near Tifton, GA, on the population dynamics of yellow nutsedge and certain annual weeds in peanut-corn and peanut-cotton rotations. Converse rotation sequences were included to eliminate year effects. Continuous fallow plots (noncrop) were included for comparison. Within each crop, including fallow, were 3 levels of weed management: low, moderate, and intensive. Weed densities and numbers of yellow nutsedge tubers were not affected by crop rotations, but they were affected by individual crops and weed management systems in each crop. Fallow plots, including those with intensive fallow weed management using tillage and nonselective herbicides, consistently contained more yellow nutsedge plants and tubers than other plots. Moderate and intensive weed control systems in peanut and cotton reduced yellow nutsedge densities and tubers, but only peanut yields were increased by intensive weed management. Weed management systems did not affect yellow nutsedge densities in corn, although yields were increased by moderate and intensive systems due to improved control of other weeds. Our results suggest that uninterrupted plantings of peanut, corn, or cotton with moderate levels of weed management are generally sufficient to suppress yellow nutsedge and allow for optimum crop yield. If fields are fallow, yellow nutsedge population densities and tubers will increase exponentially, even with intensive fallow weed management.

Alternative genes for resistance to Bean Common Mosaic Virus in common bean (Phaseolus vulgaris L.) are necessary as a result of the recent introduction of necrosis-inducing strains of this virus into the USA. The recessive bc-3 gene confers resistance against all known strains of this pathogen. We describe here experiments to develop a relatively easy-to-use procedure to introgress the bc-3 gene into elite bean cultivars. First, we employed bulked segregant analysis to identify RAPD markers linked to the bc-3 locus. The ROC11/350/420 marker was codominant with the bc-3 gene and the ROC20/460 marker was dominant and linked in trans. A survey of cultivated materials allowed us to identify the likely evolutionary origin of the bc-3 resistance allele as a member of the Mesoamerican gene pool, probably of race Mesoamerica. Polymorphism of the RAPD markers in a Davis common bean mapping population (BAT93 x Jalo EEP558) allowed us to map the markers and, by inference, the bc-3 gene to linkage group D6. Second, we used sequence information from the cloned RAPD fragments to design longer, more reliable PCR primers that differentiate individuals homozygous for the resistance allele from susceptible genotypes in segregating populations of Andean origin. Third, we developed a marker tagging system that used a simplified DNA extraction technique and a PCR-based assay to identify the genotype of common bean plants at the bc-3 disease resistance locus. This simplified marker assisted selection system is expected to eliminate the need for costly quarantines and progeny tests in breeding programs for common bean of Andean origin.

Field studies were conducted at Tifton, GA to quantify phytotoxicity of flumetsulam on peanut as influenced by application rate and timing in a weed free experiment. Flumetsulam PPI at rates up to 0.14 kg ai/ha visibly injured peanut and reduced canopy width, but injury from PPI flumetsulam at 0.07 kg/ha or less was no worse than a standard early postemergence (EPOST) treatment of bentazon (0.6 kg ai/ha) plus paraquat (0.14 kg ai/ha). Flumetsulam EPOST at rates up to 0.07 kg/ha visibly injured peanut and reduced peanut canopy width. Flumetsulam injury at rates of 0.035 kg/ha EPOST was similar to that caused by bentazon plus paraquat. Interactive effects of PPI and EPOST flumetsulam reduced early and mid-season pod and foliage biomass more than either application alone. However, peanut recovered with final yields not affected by flumetsulam, regardless of rate or time of application.

A combination of fallow tillage and a March application of carbofuran were assessed as tactics for decreasing survival and reproduction of tobacco thrips overwintering in six harvested peanut fields. Large numbers of tobacco thrips, Frankliniella fusca (Hinds) (Thysanoptera: Thripidae), developed in three fields on volunteer peanut, Arachis hypogaea L., and winter annual weeds. Adult tobacco thrips collected during the late winter were predominantly brachypterous, with percent brachyptery averaging 71–95% for females. Brachypterous adults tended to be more abundant in fields harvested in September than in those harvested in October. Disking during November and February greatly reduced the density of volunteer peanut and winter annual weeds but did not measurably decrease abundance of brachypterous tobacco thrips. Carbofuran application reduced abundance of brachypterous adults and thrips larvae on volunteer peanut by 85–100% during the early spring. Post-harvest tillage and carbofuran application did not measurably reduce incidence of tomato spotted wilt virus in the subsequent peanut crop. Implications for winter ecology and management of spotted wilt are discussed.

Our goal was to investigate in more detail wild and cultivated common bean (Phaseolus vulgaris) accessions from northwestern South America (Colombia, Ecuador, and northern Peru) because prior research had shown this region to be the meeting place of the two major gene pools (Middle American and Andean) of common bean. Explorations were conducted in these countries to collect additional materials not represented in germplasm collections. It was possible to identify wild common bean populations in Ecuador and northern Peru, where they had never been described before. In addition, we were able to extend the distribution of wild common bean in Colombia beyond what was known prior to this study. In all areas, the wild common bean habitat had suffered severely from destruction of natural vegetation. In Colombia, wild common beans were found on the Eastern slope of the Andes (in continuation of its distribution in Venezuela), whereas in Ecuador and northern Peru they were found on the western slope of this mountain range. This geographic distribution was correlated with an ecological distribution in relatively dry environments with intermediate temperatures (known as “dry mountain forest”). Isozyme andphaseolin seed protein analyses of the northern Peruvian and Ecuadoran wild populations showed that they were intermediate between the Middle American and Andean gene pools of the species. Phaseolin analyses conducted on landraces of the Upper Magdalena Valley in Colombia showed that Andean domesticates were grown at a higher altitude than Middle American domesticates suggesting that the former are adapted to cooler temperatures. Our observations and results have the following consequences for the understanding and conservation of genetic diversity in common bean and other crops: 1) Our understanding of the distribution of the wild relative of common bean (and other crops) is imperfect and further explorations are needed to more precisely identify and rescue wild ancestral populations; 2) For crops for which the wild ancestor has not yet been identified, it may be worthwhile to conduct additional explorations in conjunction with genetic diversity studies at the molecular level to guide the explorations; 3) Our study shows the benefit for more efficient germplasm conservation which can be derived from the dynamic interplay between field explorations (and other conservation operations) and molecular analyses to determine genetic distances and diversities; 4) The intermediate materials identified in northern Peru and Ecuador may have basic importance to understand the origin of the common bean and an applied role as a bridge between the Middle American and Andean gene pools; and 5) The differential adaptation to temperature of the two major cultivated gene pools may help breeders select genotypes based at least partially on their evolutionary origin.

Transcription in the human immunodeficiency virus type 1 (HIV-1) retrovirus is regulated by binding the viral Tat protein (trans-acting transcriptional activator) to the trans-activation response (TAR) RNA sequence. Here, vacuum UV circular dichroism (VUV-CD) is used to study the structure of TAR and its complex with two peptide fragments that are important for Tat binding to TAR. The VUV-CD spectrum of TAR is typical of A-form RNA and is minimally perturbed when bound to either the short or the long Tat peptide. The CD spectra of the complexes indicate an extended structure in the arginine-rich region of Tat from amino acid residue 47 through residue 58 and a short alpha-helix within the adjacent 59-72 region. Models of TAR and its peptide complexes are constructed to integrate these spectroscopic results with current biochemical data. The model suggests that (i) the arginine-rich 49-58 region is primarily responsible for electrostatic interactions with the phosphates of the RNA, (ii) the arginine side chains can additionally interact with substituent groups of the nucleotide bases to confer base recognition in the complex, (iii) the recognition of uracil-23 in TAR is facilitated by the peptide backbone, and (iv) the glutamine-rich face of an alpha-helix within the 59-72 region pairs to bases UGG at nucleotide positions 31-33 in the TAR loop and thus provides an additional motif in the Tat trans-activating protein to recognize TAR RNA.

Studies on the efficacy and economic analysis of Texas panicum management systems in corn were conducted in Georgia on a loamy sand soil in 1987, 1988, and 1989. Management systems that included butylate, EPTC, atrazine plus tridiphane, atrazine plus pendimethalin, atrazine plus trifluralin, paraquat, or ametryn acceptably control Texas panicum. Corn yields were not affected significantly by the Texas panicum management systems. Overall net returns calculated for corn production indicated that systems which included postemergence applications of atrazine, pendimethalin, trifluralin, paraquat, ametryn, or cultivation alone gave the highest net returns. Systems which included butylate, EPTC, or tridiphane frequently had significantly lower net returns.

Three RFLP maps, as well as several RAPD maps have been developed in common bean (Phaseolus vulgaris L.). In order to align these maps, a core linkage map was established in the recombinant inbred population BAT93×Jalo EEP558 (BJ). This map has a total length of 1226 cM and comprises 563 markers, including some 120 RFLP and 430 RAPD markers, in addition to a few isozyme and phenotypic marker loci. Among the RFLPs mapped were markers from the University of California, Davis (established in the F2 of the BJ cross), University of Paris-Orsay, and University of Florida maps. These shared markers allowed us to establish a correspondence between the linkage groups of these three RFLP linkage maps. In total, the general map location (i.e., the linkage group membership and approximate location within linkage groups) has been determined for some 1070 markers. Approaches to align this core map with other current or future maps are discussed.

An abnormal puckered-leaf shape was recently found in the cultivated peanut (Arachis hypogaea L.). Upon crossing this true-breeding genotype between and within both subspecies, inheritance data indicated two genes with epistatic interaction controlled this unusual trait which resembles tobacco thrips (Frankliniella fusca Hind) injury on peanut leaves. No maternal or cytoplasmic effects were detected among progenies from reciprocal hybridization. Subsequent allelism tests also detected no difference between the two similar occurring puckered-leaf mutants that were independently found in different genetic lineages. A new gene symbol, puc1 Puc2, for the puckered-leaf shape is being proposed to distinguish it from the narrow leaf gene, nl, as previously reported.

Babesia bovis merozoite proteins presenting as exoantigens in in vitro culture supernatants have been characterized. Bovine antisera to B. bovis exoantigens were used to immunoprecipitate [35S]-methionine metabolically labeled or lactoperoxidase-catalyzed radioiodinated B. bovis merozoite proteins. A total of 24 metabolically labeled proteins ranging in molecular weight from 24,000 to 225,000 Da and 9 radioiodinated proteins with molecular weights varying between 24,000 and 225,000 Da were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Monoclonal antibodies to B. bovis merozoite surface proteins were also used to immunoprecipitate metabolically labeled exoantigens directly from in vitro culture supernatants. These results demonstrate epitopes from at least nine merozoite surface proteins present in the exoantigen fraction, among which are the recently characterized major surface antigens 1 and 2, rhoptry-associated protein 1, and spherical body protein 2.

We examined jay caching patterns over 3 yr in a woodland-prairie landscape in S-central Iowa. Three aspects were examined: jay habitat preferences for caching, jay caching patterns before and after fire, and the influence of predation on nuts by small mammals on tree recruitment in jay territories. Blue jays cached nuts in a wide range of habitats, from open, grassy patches to mature forest. Jays cached preferentially in regenerating woodland and edge habitats while usually avoiding grassland habitats. Caching increased in grassland following a controlled burn. Detection by small mammals of artificial nut caches placed by the investigator was extremely

Angular leaf spot (ALS) disease of common bean (Phaseolus vulgaris) is caused by the imperfect fungus Phaeoisariopsis griseola and severely reduces bean yields in tropical and subtropical countries. Breeding for disease resistance has been difficult because there is substantial pathogenic variation among fungal isolates. Random amplified polymorphic DNA (RAPD) markers were used to characterize 62 P griseola isolates from three countries (Malawi, the United States, and Brazil). The gene pool of the bean plants from which the isolates were obtained was determined by isozyme and phaseolin analysis. Eleven primers generated reproducible and distinct RAPD patterns that divided the P griseola isolates into two major groups. Group 1 (Andean) isolates were generally recovered from Andean gene pool materials, whereas group 2 (Mesoamerican) isolates were recovered from Mesoamerican materials. Phaeoisariopsis griseola isolates representing groups 1 and 2 were inoculated onto selected Andean and Mesoamerican bean genotypes. Group 1 isolates were more pathogenic on Andean beans, whereas group 2 isolates were more pathogenic on Mesoamerican beans. RAPD and pathogenicity data suggest that groups 1 and 2 may have originated in the Andes and Mesoamerica, respectively, and that coevolution of the P griseola fungus and its common bean host has resulted in increased levels of disease in this host-pathogen interaction. The results have implications in development of ALS breeding strategies

We investigated the relation between fire and oak recruitment in a mosaic of grassland and forest communities in S-central Iowa. Fire caused high ramet mortality, but low genet mortality among oaks ?50 cm in height. In addition to increased sprouting, fire promoted terminal dominance in oak ramets and more vigorous height growth. This vigorous height growth resulted in a larger proportion of stems in the >50-cm height class at the end of the study in the burned areas compared to the unburned area. The patterns of recruitment during our 4-yr study included 1 yr of high recruitment followed by 3 yr of low but steady recruitment. Annual variation in oak recruitment proved to be statistically significant, but differences in recruitment rates between burned and unburned areas were not significant. On average, recruitment rates for oak were low in our study area, but mortality rates were also low on this dry, S-facing slope. Quercus was neither a rapid colonizer nor necessarily a rapid grower during its early development on the site. It can be best characterized as persistent with its opportunity for establishment enhanced by fire.

The age structure of table mountain pine Pinus pungens Lambert was examined in three pine-oak forests in southwestern Virginia. The age distribution of P. pungens was bimodal with a major peak in the large tree age classes and a smaller secondary peak in the seedling age classes. The predominance of advanced regeneration of oaks and other gap-exploiting woody species, and the underrepresentation of P. pungens seedlings and small trees, indicates that maintenance of P. pungens in these forests is unlikely under current disturbance regimes. It is hypothesized that the P. pungens populations studied originated from seed trees left on the sites following heavy logging and fires at the turn of the century.

The influence of leaf litter and soil moisture regime on early establishment of table mountain pine Pinus pungens Lambert was evaluated in a greenhouse study. The influence of leaf litter on emergence and survival of seedlings was substantial and varied with litter type. Pine litter generally supported greater seedling emergence than litter-free or oak-litter treatments, and only under daily watering did emergence in the litter-free treatment approach that observed in pine litter. Oak litter, in all but the lowest soil moisture regime, depressed seedling emergence relative to that recorded from pine litter and litterfree treatments. Significant statistical interactions indicated that the effects of leaf litter and soil moisture regime were not independent; leaf litter significantly decreased evaporative losses which resulted in greater seedling emergence and survival at low soil moisture regimes.

The major acid-soluble spore proteins (ASSPs) isolated from mature spores of Bacillus subtilis are designated alpha, beta, and gamma (about 60, 60, and 100 amino acids in length, respectively). Alpha and beta are very similar, and gamma is very similar to a less predominant ASSP called delta (about 115 amino acids). A minor and very basic ASSP called epsilon is the same size as alpha and beta but is unrelated antigenically. These and several minor ASSPs comprise at least three related families of sporulation-specific gene products. Expression of the alpha and beta genes, detectable as functional mRNA in vitro, coincides with the time of synthesis of all of the major ASSPs in vivo. This apparently coordinate expression is dependent on at least the spo0A, spoIIA, and spoIIIA loci, but not on the spoIVA or spoVA loci, consistent with the late stage of this expression (initiating at 3.5 h after the start of sporulation and peaking at 5 h after start of sporulation). A few minor ASSPs may be asynchronously expressed.

Circular dichroism (CD) spectra in the vacuum UV region for different conformations of poly d(G-C) X poly d(G-C) and poly r(G-C) X poly r(G-C) are very characteristic. The CD of the RNA in the A-form (6 M NaClO4 and 22 degrees C) is very similar to that of the DNA in 80% alcohol where it is believed to be in the A-form. With the exception of the longest wavelength transition, the CD of the RNA in 6 M NaClO4 at 46 degrees C is similar to the CD of the DNA under conditions where it is believed to be in the Z-form (2 M NaClO4). This substantiates that poly r(G-C) X poly r(G-C) assumes a left-handed Z-conformation in 6 M NaClO4 above 35 degrees C. CD spectra for the left-handed Z-forms of both the RNA and DNA are characterized by an intense negative peak at 190-195 nm, a crossover at about 184 nm, and an intense positive peak below 180 nm. The right-handed A- and B-forms of RNA and DNA all have an intense positive peak in their CD spectra near 186 nm. The large difference in CD in the range 185-195 nm for right- and left-handed conformations of nucleic acids can be used to identify the sense of helix winding.

The product of the abrB gene of Bacillus subtilis is an ambiactive repressor and activator of the transcription of genes expressed during the transition state between vegetative growth and the onset of stationary phase and sporulation. Purified AbrB protein binds specifically in a highly co-operative fashion to fragments of DNA containing the promoters it affects. DNase I footprints of the binding regions in these promoters revealed large protected areas of 50-120 nucleotides or more depending on the promoter. Methylation protection experiments gave protected guanine residues on only one face of the DNA helix. A consensus sequence could be deduced around these guanine residues that was not found around non-protected guanine residues in the footprint region. The results suggested that stationary phase functions and sporulation are repressed during active growth by AbrB and other transition state regulators by binding to the affected promoters in a concentration-dependent manner.

Circular dichroism studies were carried out in the vacuum ultraviolet region for 11 S and 5.6 S species of acetylcholinesterase from Torpedo. As the 5.6 S acetylcholinesterase forms larger oligomers in the absence of detergent, the CD spectrum was measured both with and without detergent. Secondary structure analysis of the CD spectrum for 11 S acetylcholinesterase shows 33% alpha-helix, 23% beta-sheet (14% antiparallel and 9% parallel), 17% turns and 26% other structure. Binding of edrophonium to the active site of 11 S acetylcholinesterase increases alpha-helix, while binding of propidium to the peripheral site increases beta-sheet. The beta-sheet content is slightly higher for 5.6 S than 11 S acetylcholinesterase in water. When the detergent is added to 5.6 S acetylcholinesterase, the 190 nm and 220 nm bands become less intense, although the analyses of the two spectra are similar. No significant change is observed for the 5.6 S form in either solvent on binding ligands. The prediction of both parallel and antiparallel beta-sheet suggests that at least one domain in these multidomain proteins belongs to the alpha/beta tertiary structural type.

The circular dichroism of membrane-free folded chromosomes from E. coli was measured and analyzed. The spectrum can be explained as a simple linear combination of the individual spectra of E. coli RNA, and E. Coli DNA in the B form. No contribution from A form or C form DNA was detected. There was evidently some real variation in the ratio of the two nucleic acids from preparation to preparation, but the average value was 24% RNA and 76% DNA. No significant light scattering was observed and the analyses indicated no contribution to the circular dichroism from scattering artifacts. Apparently, combining DNA, RNA, and protein into membrane-free folded chromosomes does not change the secondary structure of the DNA or RNA from that found for the free nucleic acid in the same solvent system.

Acid-soluble spore proteins (ASSPs) comprise about 5% of the total protein of mature spores of different Bacillus subtilis strains. They consist of three abundant species, alpha, beta, and gamma, four less abundant species, and several minor species, alpha, beta, and gamma make up about 18, 18 and 36%, respectively, of the total ASSPs of strain 168, have molecular weights of 5,900, 5,9000, and 11,000, respectively, and resemble the major (A, C, and B) components of Bacillus megaterium ASSPs in several respects, including sensitivity to a specific B. megaterium spore endopeptidase. However, they have pI's of 6.58, 6.67, and 7.96, all lower than those of any of the B. megaterium ASSPs. Although strains varied in the proportions of different ASSPs, to overall patterns seen on gel electrophoresis are constant. ASSPs are located interior to the cortex, presumably in the spore cytoplasm, and are synthesized during sporulation and degraded during germination.

The secondary and tertiary structure of T4 bacteriophage dihydrofolate reductase is investigated by vacuum ultraviolet circular dichroism (CD) spectroscopy and probability analysis of the primary amino acid sequence. The far ultraviolet CD spectrum of the enzyme in the range of 260-178 nm is analyzed by the generalized inverse and variable selection methods developed by our laboratory. Variable selection yields an average content of 26% alpha-helix, 21% antiparallel beta-sheet, 10% parallel beta-sheet, 20% beta-turns, and 32% "other" structures within the T4 protein. The characteristic peaks of the CD spectrum indicate that the enzyme has a lot of antiparallel beta-sheet, which is typical of the alpha + beta tertiary class of globular proteins. The secondary structure of the protein is also analyzed by using four statistical methods on the amino acid sequence. Although the secondary structures predicted by each individual statistical method vary to a considerable extent, the fractions of each structure jointly predicted by a majority of the methods are in excellent agreement with our CD analysis. The alternating arrangement for some segments of alpha-helix and beta-sheet predicted from primary structure to be within the enzyme is characteristic of proteins containing parallel beta-sheet. This supports our conclusion that the protein contains both parallel and antiparallel beta-sheet structures, but finding both types of beta-sheet also means that the protein may have the variation on alpha/beta tertiary structure recently found in EcoRI endonuclease and thymidylate synthase. These observations, in conjunction with other physical properties of the T4 reductase, suggest that the enzyme perhaps shares an evolution in common with the dihydrofolate reductases derived from type I R-plasmids rather than with the host-cell protein.

The work recorded above has served to corroborate the observations of other writers, notably of Noguchi, that in many human sera, if not in all, there develop, on standing, anticomplementary bodies which are delicately thermolabile, being inactivated by heating to 56° C. for fifteen to twenty minutes. It has appeared that these bodies may occasionally be present in sera which, after heating, may develop the thermostable anticomplementary body referred to by other authors. It has become evident also that the speed of development of the thermolabile anticomplementary body in different sera is subject to much variation. The thermolabile body appears as the complement disappears. The question arises whether the thermolabile anticomplementary body may not be originally present in the serum, temporarily masked by the native complement. This would seem improbable from the fact that titration has shown that 0.1 and 0.2 cubic centimeter of the inhibiting serum will often inhibit as much as 0.6 cubic centimeter of fresh guinea-pig complement, a quantity superior to the amount of complement present originally in the antihemolytic serum. It seems, therefore, that the anticomplementary body must actually be formed in the serum during the period of preservation. The thermolabile antihemolytic body studied by us is like the thermostabile body investigated by Noguchi, in that it inhibits alien as well as homologous complement; it is unlike the thermostabile body, however, in that it cannot be absorbed from serum by digestion with red cells, nor does it render the treated cells more resistant to hemolysis. The thermolabile body may be removed from inhibiting sera by precipitating the globulins. A solution of the glotmiins then manifests a thermolabile anticomplementary action. No relationship between a clinical condition and the appearance of these bodies in the sera, has been found. As a practical result these studies have shown, as have those of Noguchi, that the complement fixation tests should never be made with certain sera which have been preserved for some time without inactivation.

Flow linear dichroism studies of DNAs from Clostridium perfringens, Escherichia coli, and Micrococcus luteus are extended into the vacuum UV region to 175 nm. The short-wavelength pi pi region shows a less negative reduced linear dichroism than the well-studied long-wavelength pi pi region. These results are independent of the type of DNA and the concentration of salt over the range 0.001 to 1.0 M. This proves that the bases are not perpendicular to the flow orientation. Assuming that the DNA tends to align along its helix axis, the largest angle that the bases can make with the helix axis is 73 +/- 3 degrees.

Several properties of the major proteins degraded during germination of spores of Bacillus cereus, Bacillus megaterium, and Bacillus subtilis have been compared. All of the proteins had low molecular weights (6,000 to 13,000) and lacked cysteine, cystine, and tryptophan. The proteins could be subdivided into two groups: group I (B. megaterium A and C proteins, B. cereus A protein, and B. subtilis alpha and beta proteins) and group II (B. cereus and B. megaterium B proteins and B. subtilis gamma protein). Species in group II had lower levels of (or lacked) the amino acids isoleucine, leucine, methionine, and proline. Similarly, proteins in each group were more closely related immunologically. However, antisera against a B. megaterium group I protein cross-reacted more strongly with the B. megaterium group II protein than with group I proteins from other spore species, whereas antisera against the B. megaterium group II protein cross-reacted most strongly with B. megaterium group I proteins. Analysis of the primary sequences at the amino termini and in the regions of the B. cereus and B. subtilis proteins cleaved by the B. megaterium spore protease revealed that the B. cereus A protein was most similar to the B. megaterium A and C proteins, and the B. cereus B protein and the B. subtilis gamma protein were most similar to the B. megaterium B protein. However, amino terminal sequences within one group of proteins varied considerably, whereas the spore protease cleavage sites were more highly conserved.

Trypsin digestion of the protamine-like protein from Spisula solidissima has revealed the existence of an internal resistant core. The peptide contains 75 amino acid residues, and its primary structure shows some conserved sequences that are common to those found in the core of the somatic histone H5 from chicken erythrocytes. The secondary structure of this core exhibits 33% antiparallel beta-sheet, 18% beta-turns, 37% random coil, and only 10% alpha-helix, in contrast to histone H5. Hydrodynamic measurements indicate a compact globular assembly for the tertiary structure of this peptide, when compared to the more extended shape observed for the whole protein. The possible relatedness of this protein to the histone H1 family is discussed.

Physiological resistance is an important component of integrated strategies used to control white mold [caused by Sclerotinia sclerotiorum (Lib.) de Bary] a major disease of common bean (Phaseolus volgaris L.) in North America. Information pertaining to inheritance of physiological resistance, as detected by the greenhouse straw test, and its relationship with field resistance is lacking. The objectives of this study were to compare physiological resistance as detected by two separate straw tests with field resistance, evaluate heritability of physiological resistance, and to characterize the disease reaction of G 122 by quantitative trait locus (QTL) analysis. This was done in a recombioant inbred population (A 55/G 122) consisting of 67 F derived lines. The greenhouse tests with five and six replications, respectively, and the field test with three replications were conducted in randomized complete block designs. Moderate heritability for disease reaction (scored from 1 = no symptoms to 9 = severe disease) was observed across the straw tests (0.65) and in the field (0.78). Inheritance of disease reaction was further investigated with a framework linkage map composed of 74 markers, Interval mapping detected a QTL on linkage group B7 near the phaseolin seed protein (Phs) locus that explained 38% of the phenotypic variation for disease score across the straw tests. The same B7 QTL (26%), and an additional QTL (18%) on B1 near the fin gene for determinate growth habit conditioned field resistance. A QTL (34%) for canopy porosity, a measure of potential disease avoidance, also mapped to the fin locus. Results confirmed that physiological resistance as detected by the straw lest was an integral component of field resistance, and that both physiological and avoidance mechanisms contributed to field resistance in the A 55/G 122 population. The landrace G 122 clearly provides breeders with a heritable source of physiological resistance to combat white mold discase.

The circular dichroism of Eco RI restriction endonuclease was measured to 178 nm and analyzed for secondary structure. The results (33% alpha-helix, 25% beta-sheet, 17% turns, and 25% other structures) compare well with our joint prediction from sequence data.