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Information concerning the amount and distribution of genetic diversity in China, where the soybean [Glycine max (L.) Merr.] was domesticated, is important for effective soybean germplasm management and use. This research (see Chen and Nelson, 1645–1652) adds to that information for four geographically diverse provinces (Zhejiang, Sichuan, Gansu, and Hebei) and confirms the relationship between origin and genetic diversity, on the basis of RAPD fragments, for primitive cultivars. Although unique fragments were identified within each province, the patterns of divergence among the provinces was primarily attributable to differences in fragment frequencies.
Competition between Tomato and Yellow Nutsedge
Nutsedge (Cyperus esculentus L.) competes with the tomato (Lycopersicon esculentum L.) crop largely below ground. Ozone reduces root development and thus may alter this competitive relationship. Shrestha and Grantz (1587–1595) found that in open top chamber experiments with potted plants, moderate ozone exposures increased the competitiveness of nutsedge with tomato, but this reversed under high ozone concentrations at which nutsedge growth was also reduced. Current air pollution may be increasing the competitiveness of nutsedge, increasing the requirements for weed management and herbicide application. Further increases in ambient ozone may restore a balance between these two species.
Induced x Natural Tetraploid Russian Wildrye
Because of restrictions imposed by hybridization barriers, Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski] breeders have usually limited themselves to selection and hybridization within ploidy levels. Jensen et al. (1305–1311) evaluated the potential to combine gene(s) from diploid and tetraploid Russian wildrye into a stable breeding population. Cytologically, the hybrid population behaved as an autotetraploid. Narrow-sense heritabilities were 31, 63, 17, and 23% for dry matter yield, total seed yield, 100-seed weight, and rate of seedling emergence, respectively. Positive responses to selection pressure for improved seed yield, rate of seedling emergence, and dry matter production were achieved.
Air Temperature, Seed Germination, and Seed Vigor
Egli et al. (1329–1335) investigated the effects of high temperature during seed filling on soybean [Glycine max (L.) Merrill] seed germination and vigor in the field. Standard germination (SG) and accelerated-aging germination (AA), a measure of seed vigor, of seed produced in Kentucky, Mississippi, Arkansas, and Texas declined as maximum air temperature during seed filling increased from 24 to 37.6°C, and AA was reduced more than SG. Seed of ‘Hutcheson’ (maturity group V) was more sensitive to high temperature than DP4690 (maturity group IV). The AA of Hutcheson seed was above 80% when average maximum temperatures during seed filling were below 31°C.
Effects on Canola Leaf Protein Profile
In spring, canola (Brassica napus L.) may be affected by low root temperatures, poor aeration due to flooding, or both. Franklin et al. (1379–1386) treated canola plants in solution culture with roots at an ambient temperature of 24/18°C, or cooled to 10°C, with or without aeration. Negative effects of cooling and hypoxia appear to be additive, and 17 changes in protein expression were found in leaves of the cold hypoxic treatment that were not found in either cold or hypoxic treatments alone. Results suggest a more negative impact on canola growth when flooding occurs at cold temperatures.
Oat Caryopsis Size and Genotype Effects
The genetic similarity between oat (Avena sativa L.) and wild oat (A. fatua L.) precludes selective herbicide control of the weed. Previous studies have demonstrated improved crop tolerance to weed competition by planting large seeds. Therefore, Willenborg et al. (1410–1416) conducted a greenhouse study to determine the response of wild oat–oat competition to oat caryopsis size and genotype. Oat plants derived from large seeds were more competitive than those derived from small seeds. Moreover, oat caryopsis size exerted a greater effect on competition between the two species than did genotype. The results of this study suggest that oat plants derived from large-seeded caryopses may be better able to tolerate wild oat interference.
Wheat-Alien Derivatives and Fusarium Resistance
Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe, is a destructive disease of wheat (Triticum spp.) in humid growth conditions throughout the world. Lack of effective resistance to FHB has hindered development of wheat cultivars resistant to this disease. Oliver et al. (1353–1360) identified 74 wheat-alien species derivatives exhibiting a level of resistance comparable with T. aestivum ‘Sumai 3’, the most widely used source of resistance to FHB. These derivatives, including wheat-alien species amphiploids, synthetic hexaploid wheat lines, and wheat-alien species substitution and translocation lines, could serve as novel sources to enhance resistance of wheat to FHB.
Silicon Content in Different Rice Organs
Rice (Oryza sativa L.) is the most effective Si-accumulating plant species. By using a recombinant inbred line population of indica rice cross ‘Zhenshan 97B’/‘Milyang 46’, Dai et al. (1345–1352) performed quantitative trait loci (QTL) analysis to study the inheritance of Si content in rice hull (HUS), flag leaf (FLS), and stem (STS). A total of 10 QTL showing significant additive effects and 14 significant additive-by-additive (AA) interactions were detected. General contributions to the phenotype variance due to additive effects and AA effects were 29.3 and 18.6% for HUS, 14.8 and 13.6% for FLS, and 8.6 and 28.6% for STS, respectively.
Amended-Sand Root Zones and Putting Greens
Sand-based root zones are commonly used for construction of golf course putting greens. A field study by Murphy et al. (1511–1520) evaluated eleven sand-based root zones varying in amendment on the establishment of turf in two microenvironments. Greater water retention and nutrient retention in a mixture improved turf establishment; however, low water retention in a mixture negated the advantage of increased nutrient retention over time. Longer-term study of root zones is needed to verify the persistence of turf responses, especially considering the capillary porosity of better-performing root zone mixtures was unacceptable by that USGA criterion.
Core of Core Collection for Peanut
More efficient methods for evaluating and maintaining genetic diversity in germplasm collections are needed. Holbrook and Dong (1540–1544) selected a core of the core collection (mini core) and evaluated its usefulness in identifying genes of interest in peanut (Arachis hypogaea L.). Results indicated that the mini core collection can be used to improve the efficiency of identifying desirable traits in the core and the entire collection. The core of the core approach should be particularly useful for traits that are difficult and/or expensive to measure.
Norstar Wheat BAC Library
Ratnayaka et al. (1571–1577) constructed a bacterial artificial chromosome (BAC) library from leaf DNA of a commercially grown winter wheat cultivar (Triticum aestivum L. cv. Norstar) that is highly tolerant to low temperatures (LT50 = –24°C). In excess of 1.2 x 106 clones propagated in E. coli were obtained, archived in 384-well microtitre plates, and stored at –80°C. More than 99.1% of the recombinant plasmids contained inserts (max 262 kb; average 75 kb), corresponding to 
5 haploid genomes. The BAC library was gridded onto high-density filters and will be used for isolation of genetic loci associated with cold-tolerance and grain quality traits.
Pollen-Mediated Gene Flow in California Cotton
The sensitivity of export markets to genetically engineered traits has made pollen-mediated gene flow (PGF) a significant issue in cotton (Gossypium hirsutum L.) breeding, seed production, and international trade. Van Deynze et al. (1565–1570) measured PGF under field conditions in California with and without added honeybee pollinators using a herbicide bioassay. PGF decreased exponentially with increasing distance, falling below 1% at 9 m with honeybees and at 1 m in the absence of honeybees.
Automated Digital Image Analysis
Manual analysis of digital images to evaluate turf may be tedious and cumbersome. Karcher and Richardson (1536–1539) developed a user-friendly macro to automate batch analysis of an unlimited number of turf images. The macro, which is freely available for download, considerably reduces the labor associated with digital image analysis.
Ecotype Derived White Clover Cultivars
Ladino white clover (Trifolium repens var. giganteum Lagr-Foss) cultivars are not dependable when interplanted into southern perennial grass pastures. Bouton et al. (1596–1602) found naturalized white clover (T. repens L.) ecotypes collected in Georgia pastures to be the intermediate leaf types and not Ladinos. From these ecotypes, two commercial cultivars, ‘Durana’ (ecotype) and ‘Patriot’ (ecotype x ladino hybrid) were developed. In this paper, the ability of ecotype based white clover cultivars, specifically Durana and Patriot, to provide better animal performance than the ladino cultivar ‘Regal’ because of increased persistence and an ability to sustain a higher clover dry matter percentage was recorded.
Simultaneous Agronomic and Molecular Characterization
Characterizing entries by molecular markers and/or agronomic attributes is a common practice, but studies that simultaneously represent molecular and agronomic traits are less frequent. Bramardi et al. (1603–1609) illustrate the use of Generalised Procrustes Analysis (GPA) as a method to ordinate the entries of a well-known collection of cucumber (Cucumis sativus L.) cultivars and compare with ordinations provided by alternative approaches. GPA allows the most suitable distance for each type of variable and ordination method to be used, and results suggest that it was the alternative that better fit the known grouping of entries. The merits of GPA are of general applicability in plant genetic resources evaluation.
Genetic Variation in Sorghum Germplasm
Abu Assar et al. (1636–1644) fingerprinted sorghum [Sorghum bicolor (L.) Moench] germplasm (96 accessions) from Sudan, ICRISAT, and Nebraska, USA, using simple sequence repeats (SSRs). UPGMA clustering revealed two main clusters comprising mainly nonimproved germplasm and improved genotypes. Grouping of accessions matched with the geographical origin and/or pedigree information (Sudan, USA, ICRISAT), the adaptation zone (Gadarif area, Sudan), and morphological characters (Feterita, Mugud, and Milo types) indicating the strong differentiation within sorghum.
Low-Input vs. High-Input Selection Environments
Brancourt-Hulmel et al. (1427–1431) assessed the efficiency of low-input vs. high-input selection environments to improve winter wheat (Triticum aestivum L.) for low-input environments. Three standard cultivars, 11 parents, and 270 lines bred in INRA were investigated during 2 yr at three French locations; four agronomic treatments combining two fungicide levels with two nitrogen levels were used. Genetic and error variances, heritabilities, and genetic correlations were investigated for grain yield and grain nitrogen content to assess the relative efficiency of indirect and direct selection. Indirect selection was never more efficient than direct selection. Breeding programs targeting low-input environments should include low-input selection environments to maximize selection gains.
Rice Gall Midge Resistance Gene
Kumar et al. (1631–1635) studied gall midge (Orseolia oryzae Wood-Mason) resistance gene present in Indica rice (Oryza sativa L.) BG 380-2 and its relationship to previously identified resistance genes. Inheritance studies identified a single dominant gene, Gm10, for gall midge resistance in BG 380-2. This new resistance gene will be useful in breeding new varieties and for pyramiding multiple genes for durable resistance to rice gall midge.
Histology of Cold-Hardened Oat Crowns
The crown is the overwintering tissue in winter cereals, but clear histological observations of this tissue have not been published. Livingston et al. (1545–1558) used light microscopy and digital photography to document changes in the histology of the crown as it recovered from freezing. As compared with unfrozen plants, in the recovering plants, the authors discovered vessel plugging, nuclear pycnosis, cell rupture, tissue disruption, and complete disintegration in numerous cells types within the crown. These results indicate that biochemical and genetic analysis will need to be conducted on specific tissue or even specific cell types within the crown if the complex nature of freezing resistance is to be clearly understood.
Partial Fusarium Head Blight Resistance
Fusarium head blight (FHB, caused by Fusarium graminearum Schwabe) has caused devastating losses to yield and quality of barley (Hordeum vulgare L.) produced in the northern Great Plains. Thirty-five barley unadapted germplasm lines with partial FHB resistance have been identified. Urrea et al. (1235–1240) compared these barley germplasm lines with adapted cultivars. None of the FHB-resistant barley lines had acceptable malt quality. Kernel plumpness, grain protein concentration, and malt extract were the traits impacted most severely. The FHB-resistant barley germplasm lines headed significantly later than the adapted barley cultivars. Most FHB-resistant germplasm lines were susceptible to foliar diseases common to the northern Great Plains.
Oat Agronomic and Physical Kernel Traits
Understanding relationships among agronomic and physical kernel traits and grain composition in oat (Avena sativa L.) and the effects of genotype and genotype x environment interactions can assist plant breeders in selecting lines with greatest potential as parental stocks. Thirty-three oat genotypes were grown by Peterson et al. (1249–1255) in nine environments in Idaho and analyzed for various traits of economic or nutritional importance.
Advanced Hybrid Wheatgrass Cytology and Fertility
Low chromosome pairing and reduced fertility are often the result of wide hybrids between two wheatgrasses species used to combine desirable traits. In a study by Jensen (1211–1215), chromosome pairing and fertility of advanced F generation and amphiploid hybrids between Elymus lanceolatus (Scribn. & Smith) Gould and E. caninus (L.) L. were studied. Seed set data in the F7 and F8 generations demonstrated that fertility can be restored in F1 hybrids that exhibit regular chromosome pairing with limited fertility. However, fertility declined in each subsequent generation in the amphiploid hybrids.
Soybean BSR Resistance Gene
Many soybean [Glycine max (L.) Merr.] genotypes that contain soybean cyst nematode (SCN, Heterodera glycines Ichinohe) resistance from PI 88788 also have resistance to brown stem rot [BSR, caused by Phialophora gregata (Allington & Chamberlain) W. Gams f. sp. sojae Kobayashi, Yamamoto, Negishi and Ogoshi.]. In Patzoldt et al. (1241–1248), the genetic basis of BSR resistance in Bell, a cultivar with SCN resistance from PI 88788, was evaluated. These evaluations show that Bell has a major BSR resistance gene on soybean linkage group (LG) J that traces to PI 88788. This gene maps to the same genetic region where a minor SCN resistance gene was previously mapped, which explains the association observed between BSR and SCN resistance. All other mapped BSR resistance genes also have been located to the same region on LG J, suggesting that there is limited diversity for BSR resistance in soybean.
Self-Compatibility Genes in Buckwheat
A new self-pollinated buckwheat is being developed from interspecific crosses between common buckwheat (Fagopyrum esculentum Moench) with self-incompatibility and a wild species, F. homotropicum Ohnishi, with self-compatibility. An understanding of the genetic interaction between the two breeding systems is an important component of this development. Wang et al. (1229–1234) analyzed eight F2 populations from the single F1 plants of the four interspecific crosses, as well as their corresponding backcross populations and the F3 progeny. The segregation patterns supported the control of self-compatibility in buckwheat by two complementary genes with three alleles at the first locus, Sh, and two alleles at the second locus, Sc. The study provides guidance for breeding self-pollinated buckwheat that will promote production of this highly nutritional crop.
Morning—Evening Orchardgrass Carbohydrate Density
Herbage soluble carbohydrate levels are typically lowest in morning and highest in evening, but effects of morning (AM) vs. evening (PM) pasture allocation on soluble carbohydrate intake by grazing animals are not well understood. Griggs et al. (1295–1304) compared orchardgrass (Dactylis glomerata L.) nonstructural carbohydrate and digestibility levels during 24-h clipping sequences initiated in PM and AM in three seasons. Digestibility and carbohydrate levels were often higher for PM clipping sequences, but differences between 24-h AM and PM means were small. Evening allocation of daily herbage could have increased 24-h mean dietary carbohydrate density relative to AM allocation if herbage consumption is proportionately higher in the PM than we simulated.
Drought Resistance Traits in the Peanut Mini Core Collection
Upadhyaya (1432–1440) evaluated 184 peanut (Arachis hypogaea L.) mini core entries and four control cultivars for two traits related with drought resistance- specific leaf area (SLA) and soil plant analysis development (SPAD) chlorophyll meter reading (SCMR), and 19 vegetative, reproductive, and quality traits in two seasons to identify drought resistant genotypes, and evaluate relationship between and relative stability of SCMR and SLA. SCMR was more stable than SLA. On the basis of SLA and SCMR values compared with the best control cultivar, 18 diverse drought resistant genotypes were selected for use in the peanut improvement programs to develop drought resistant cultivars with a broad genetic base.
Genetic Diversity of Indian Wheats
The proper maintenance and use of wheat (Triticum aestivum L.) genetic resources requires information about the genetic diversity available. Ram et al. (1256–1263) used Acid-PAGE gliadin patterns because they are highly polymorphic to access genetic diversity of Indian wheat varieties developed during last five decades across the country. The possible associations of specific gliadin patterns with environmental adaptation were also identified. The study revealed extensive polymorphism in gliadin pattern among the varieties. Data demonstrated that there was enhanced use of 1B.1R translocation from 1990 onwards. The information can be used in breeding to maintain wheat genetic diversity in India.
Fagopyritol Accumulation in Buckwheat Seeds
Common buckwheat (Fagopyrum esculentum Moench) embryos accumulate six different fagopyritols (
-galactosides of D-chiro-inositol) during seed maturation. Fagopyritol A1 is similar in structure to a putative insulin mediator believed to be deficient in subjects with noninsulin dependent diabetes mellitus and polycystic ovary syndrome. Horbowicz and Obendorf (1264–1270) analyzed embryo soluble carbohydrates during seed development on buckwheat plants grown at 15, 22, or 30°C. Total soluble carbohydrates remained constant across seed maturation temperatures, but the composition of carbohydrates changed in response to different maturation temperatures. Fagopyritol A1 and fagopyritol B1 were highest in seeds matured at 15°C, whereas fagopyritol A2, fagopyritol B2, fagopyritol A3, raffinose, and stachyose were higher in seeds matured at 30°C. Cool temperatures during buckwheat seed maturation can result in increased seed size and yield of fagopyritol A1 and fagopyritol B1 in embryos for nutritional and medicinal applications.
Rice Germplasm Response to Straighthead
Straighthead resulting in sterility of the florets is a physiological disease that reduces grain yield in rice (Oryza sativa L.), and widely grown U.S. cultivars are susceptible. Yan et al. (1223–1228) studied 10 U.S. and 126 foreign cultivars for straighthead induced by arsenic. Straighthead caused grain yield reductions from 24 to 96% and 19 resistant cultivars from China with no yield reductions were identified. These foreign cultivars are available to be used for improving U.S. rice cultivars for straighthead resistance.
Cyclitols and Galactosyl Cyclitols in Soybean Seed
Galactopinitols and fagopyritol accumulate in maturing soybean [Glycine max (L.) Merr.] seeds, but there is no evidence for the synthesis of pinitol and chiro-inositol in embryos. Gomes et al. (1312–1319) analyzed compounds downloaded from seed coats on soybean plants and also cyclitol galactosides in mature seeds of soybean stem-leaf-pod explants fed free cyclitols. myo-Inositol, pinitol, and chiro-inositol were formed in maternal tissues, transported to seeds, and unloaded from seed coats to embryos, whereas galactopintiols and fagopyritols were synthesized in embryos from transported pinitol and chiro-inositol. Accumulation of galactopinitols and fagopyritols in seeds was limited by the supply of pinitol and chiro-inositol to the embryo.
Disease Resistance of NSGC Barley Accessions
Cultivated barley (Hordeum vulgare subsp. vulgare L.) accessions from the USDA-ARS National Small Grains Collection (NSGC) have been tested systematically for the past 20 yr for disease and insect resistance, but little analysis of the data has been undertaken previously. Bonman et al. (1271–1280) analyzed the resistance to four diseases and one insect pest with respect to (i) geographic origin of resistant accessions, (ii) relationship to other NSGC descriptor data, and (iii) relationships among resistances. Centers of concentration for certain resistances were identified, including eastern Africa, western Turkey and the Caucasus, and South-Central Asia. Information from this study will be used to guide future NSGC acquisition and evaluation efforts.
Host-Endophyte Specificity in Sardinian Tall Fescue
The possible exploitation of advantages induced by endophytic fungi [Neotyphodium coenophialum (Morgan-Jones et Gams) Glenn, Bacon et Hanlin] to tall fescue (Festuca arundinacea Schreb. var. arundinacea Schreb.) host plants is fostering studies on this mutualistic association. Piano et al. (1456–1463) assessed the presence and main features of the grass–endophyte association in natural populations from Sardinia, Italy. The high frequency of infected populations and high levels of infection were indirect evidence of the adaptive advantage conferred by the presence of endophytes under Mediterranean conditions. A coevolutionary specificity between the Sardinian fescue germplasm and its associated endophyte was suggested by the agreement between morphology of the host plant (distinct from germplasm originating in temperate environments) and morphological and biochemical characteristics of the harbored fungus, that differed from the widespread N. coenophialum endophyte in having shorter conidia, lower ergot alkaloid concentration, and no loline alkaloid production.
Modeling Wheat Pollen-Mediated Gene Flow
Pollen-mediated gene flow occurs at low levels in wheat. Gustafson et al. (1286–1294) fit an empirical model to available wheat gene flow data and make general predictions about possible practices to manage gene flow in wheat. The effects of source field size and isolation buffers are predicted to be minimal for commercial-sized fields, and blending at harvest produces gene flow 10–50 times lower than at the field edge. Without any isolation buffers or use of border rows, field-scale gene flow is less than 0.1%, well below commercial thresholds for foreign material in wheat seed and grain.
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