Transfer of resistance to potato cyst nematode (globodera pallida) into cultivated potato Solanum tuberosum through first division restitution 2n pollen     

Rodomiro Ortiz  Javier Franco  Masaru Iwanaga 《Euphytica》1997,96(3):339-344

Genetic resistance to potato cyst nematode is considered as one of the most effective means of increasing yield and reducing nematode infestation levels in potato fields. In this study, resistance to this nematode was successfully transferred from diploid tuber-bearing Solanums to the tetraploid gene pool using a 4x-2x breeding approach. More specifically, resistance from Solanum vernei, S. sparsipilum and haploids of S. tuberosum group Andigena was introgressed into conventional tetraploid clones, using first division restitution (FDR) 2n gametes. Furthermore, some of the FDR diploid parents had similar breeding values as advanced resistant tetraploid clones which were developed only after several cycles of selection against the potato cyst nematode. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Efficiency of water use of early plantings of sunflower   总被引：4，自引：0，他引：4  

M. Auxiliadora Soriano  Francisco Orgaz  Francisco J. Villalobos  Elías Fereres   《European Journal of Agronomy》2004,21(4):465-476

Rain fed crop production in Mediterranean environments depends to a large extent on strategies that avoid the intense summer drought. Early plantings of sunflower have given consistently higher yields in such environments, but the basis for such yield increases has not been explored. We conducted two field experiments at Cordoba (Spain) to investigate the effects of an early and a late planting date on the components of water-limited crop productivity; namely, water use (T), water use efficiency (TE) and harvest index (HI) of sunflower. The results were generalized by simulating rain fed sunflower yields, under early (1 January) and late (15 March) plantings, for a 25-year period with the aid of a simulation model of the Ceres type (OILCROP-SUN) which has been validated in Cordoba. Experimental seed yields of early plantings in 1989 and 1996 were 2.0 and 3.0 t ha⁻¹, while late plantings yields were 1.3 and 2.4 t ha⁻¹, for the 2 years. Average simulated yields were 2.7 ± 1.1 and 1.9 ± 0.7 t ha⁻¹ for early and late plantings, respectively. For the 2 years, T of early plantings was higher than that of late plantings, but the response of TE and HI to planting date was not the same in the two experiments. In the simulation exercise, T and TE of early plantings were consistently higher than those of late plantings, while there were no differences in the HI for the two planting dates. We conclude that early plantings of sunflower increase rain fed yields by increasing both T and TE, while the impact of planting date on HI very much depends on the crop water stress pattern, which is quite variable from year to year even in the predictable Mediterranean environment.  相似文献   

Aflatoxin Accumulation and Associated Traits in QPM Maize Inbreds and their Testcrosses     

F. Javier Betrán  Sandeep Bhatnagar  Tom Isakeit  Gary Odvody  Kerry Mayfield 《Euphytica》2006,152(2):247-257

Preharvest aflatoxin (AF) contamination by Aspergillus flavus Link:Fr is one of the main limitations for maize (Zea mays, L.) production in the southern USA, causing enormous economic losses and posing a risk to animal and human health. The objectives of this study were (1) to estimate aflatoxin accumulation and expression of associated traits in quality protein maize (QPM) inbreds and their testcrosses, (2) to compute their repeatabilities and correlations, and (3) to study the relationship between inbred lines and their testcrosses for aflatoxin accumulation. Forty-eight inbreds and their testcrosses plus checks were grown in one and three locations in south and central Texas, respectively. Aflatoxin concentration was evaluated in the plants following inoculation with A. flavus. Average aflatoxin concentration overall for inbreds was 286.3 ng g⁻¹, and for testcrosses 596.5 ng g⁻¹ at Corpus Christi, TX, 325.1 ng g⁻¹ at Weslaco, TX, and 105.1 ng g⁻¹ at College Station, TX. Flinty orange inbreds developed from CIMMYT Population 69 were the least susceptible to aflatoxin accumulation in both inbreds and testcrosses at all locations. Repeatability for aflatoxin was 0.67 in inbreds at Weslaco, TX and 0.54 in testcrosses across locations. Aflatoxin in testcrosses was positively correlated both phenotycally and genotypically with endosperm texture and kernel integrity, and negatively correlated with grain yield and silking date. Less aflatoxin accumulation was associated with flinty endosperm texture, better kernel integrity, and later maturities. Association between the expression of traits in inbreds and aflatoxin in testcrosses was relatively high for endosperm texture (R ² = 0.62), silking date (R ² = 0.44), kernel integrity (R ² = 0.39), and aflatoxin (R ² = 0.60 for log ng g⁻¹). It seems plausible to select for associated traits having high heritabilities and strong correlation with aflatoxin, in addition to low aflatoxin accumulation in inbreds and hybrids to reduce the risk of aflatoxin contamination.  相似文献   

Morphological and molecular characterization of local varieties,modern cultivars and wild relatives of an emerging vegetable crop,the pepino (Solanum muricatum), provides insight into its diversity,relationships and breeding history     

Francisco Javier Herraiz  Santiago Vilanova  Isabel Andújar  Daniel Torrent  Mariola Plazas  Pietro Gramazio  Jaime Prohens 《Euphytica》2015,206(2):301-318

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The Impact of Trade Liberalization on Regional Disparities in Mexico   总被引：1，自引：0，他引：1  

Javier Snchez‐Reaza  Andrs Rodríguez‐Pose 《Growth and change》2002,33(1):72-90

After a long period of industrialization based on import substitution (ISI), Mexico started to open up its economy by accessing the General Agreement on Tariffs and Trade (GATT) in 1986. The export‐promotion strategy was transformed into one of regional integration with the signing of the North American Free Trade Agreement (NAFTA) in 1994. The paper explores the impact of the opening of the economy on regional disparities in Mexico using σ and β‐convergence analyses. Four different samples have been employed to control for possible data bias linked to the inclusion of oil‐producing and maquiladora‐based states. The results show that whereas the final stages of the ISI period were dominated by convergence trends, trade liberalization (GATT) and economic integration (NAFTA) have led to divergence. In particular, the NAFTA period is related to divergence regardless of the type of analysis chosen and the sample used.  相似文献   

Genetic control of Asian rust in soybean     

Aliny Simony Ribeiro  José Ubirajara Vieira Moreira  Pedro Henrique Braga Pierozzi  Breno Francovig Rachid  José Francisco Ferraz de Toledo  Carlos Alberto Arrabal Arias  Rafael Moreira Soares  Claudia Vieira Godoy 《Euphytica》2007,157(1-2):15-25

The objective of this study was to investigate the genetic mechanisms of soybean resistance to Asian rust (Phakopsora pachyrhizi Syd. & P. Syd). F2 and F3 generations from 15 diallel crosses involving six soybean cultivars, FT-2, EMBRAPA 48, BRS 154, BRS 184, BRS 214, BRS 231, were used to analyze the genetic control of Asian rust resistance in the soybean parents tested. Genetic models were fitted to means and variances of the generations tested in a completely randomized field experiment with 5,700 hill plots. The experiment was spray-inoculated twice with an isolate that was first detected during the 2002/03 season in Mato Grosso (MT) State and presently prevail in Central Brazil, at a six-day interval, on borders rows and on the useful area, respectively, with a 10⁴ spores/ml distilled H₂O suspension. Assessments were made using a diagrammatic scale for disease severity at seven and 39 days after the first detection of Asian rust in the experiments. Evaluations made in the second assessment (39 days) discriminated better between genotypes. Selection at early plant developmental stages may not result in adult resistant plants. Cultivar FT-2, which had presented monogenic resistance to a rust isolated that prevailed in the first two years of rust occurrence in Brazil, showed no resistance to the MT State rust strain used in this experiment, but eleven crosses showed genetic variability for resistance in the second assessment. Soybean rust resistant genes showing predominantly additive effects are dispersed among parents. Narrow sense heritability values ranging from 0.42 to 0.74 at the F3 family level in the second assessment suggested that selection of resistant genotypes is feasible.  相似文献   

Study of the genetic variability and similarity among and within Arachis villosulicarpa, A. pietrarellii and A. hypogaea through isoenzyme analysis     

Leticia Galgaro  Jose´ Francisco Montenegro Valls  Catalina Romero Lopes 《Genetic Resources and Crop Evolution》1997,44(1):9-15

Arachis villosulicarpa is a perennial species cultivated for its soft and tasty seeds by indigenous inhabitants of the Mato Grosso State, Brazil. Besides A. hypogaea, this species is considered as the only species of Arachis which represents a valuable food source for human consumption. Due to the lack of knowledge concerning the genetic diversity of A. villosulicarpa, this study was conducted to evaluate the genetic variability of the accessions from the Germplasm Collection of CENARGEN/EMBRAPA (Brasília, DF, Brazil) and Instituto Agrono^mico (IAC, Campinas, SP, Brazil). In addition, the genetic similarity between A. villosulicarpa, the related wild species A. pietrarellii, and the cultivated peanut A. hypogaea cv. Tatu was evaluated. From the entire sample analyzed of A. villosulicarpa, the accession from Instituto Agrono^mico showed the highest indices of diversity for both enzymatic systems analyzed, pointing this accession as a promising source of genetic variabil ity that must be preserved in the Germplasm Bank. A high level of genetic similarity was observed between A. pietrarellii and A. villosulicarpa, supporting previous suggestions that A. pietrarellii could be the ancestral progenitor species of A. villosulicarpa or that both species originated from a common ancestor.  相似文献   

Effects of forest fragmentation on the granivory of differently sized seeds     

Denise S. Donoso  Javier A. Simonetti 《Biological conservation》2004,115(1):63-70

The Maulino forest is a unique temperate ecosystem restricted to a small range of the coast of central Chile. This forest harbors many endemic species, and is threatened due to intensive deforestation and fragmentation. Currently the Maulino forest is composed of a suite of small fragments scattered in a landscape dominated by exotic plantations. The fragmentation of the Maulino forest has resulted in a higher abundance of granivores in small forest fragments compared with continuous forest. In order to determine if fragmentation-induced changes in granivore abundance affects the granivory of different size seeds, we experimentally assessed seed predation of a large-seeded species [Nothofagus glauca (Phil.) Krasser] and a small-seeded species [Nothofagus obliqua (Mirbel) Oersted] in the edges and interior of one continuous (large) forest and three small fragments (∼3 ha) surrounded by plantations of the exotic tree Pinus radiata. To determine what kind of granivores are preying upon seeds, seeds of both species were excluded from and exposed to large and small granivores. Granivory was higher in small fragments than in continuous forest, higher in the edges than in the forest interior, and higher upon large than on small seeds. Rodents, which were more abundant in forest fragments, were the main consumers. Thus, fragmentation indeed affects granivory increasing the consumption of seeds by predators inhabiting the Maulino forest remnants or coming from the matrix. This change may affect the future structure of the tree community in forest fragments.  相似文献   

Bioactive lignans from a cultivar of Helianthus annuus     

Macías FA  López A  Varela RM  Torres A  Molinillo JM 《Journal of agricultural and food chemistry》2004,52(21):6443-6447

A bioassay-guided fractionation of water extracts from Helianthus annuus cv. SH-222 was carried out. Ten lignans and a phenylpropanoid were isolated from the polar bioactive fractions of H. annuus. This study is the first to report lignans as constituents of sunflower and is the first time that tanegool has been isolated as a natural aglycone. Additionally, we report biological activities of the isolated compounds. The general bioactivity has been evaluated using the wheat coleoptiles bioassay. The phytotoxic activities of compounds pinoresinol, lariciresinol, dihydro-dehydrodiconiferilic alcohol, and l-(4'-hydroxy-3'-methoxyphenyl)-2-[4' '-(3hydroxypropyl)-2' '-methoxyphenoxy]propane-l,3-diol were also evaluated in a bioassay on the standard target species. The structure-activity relationships are discussed.  相似文献   

Mushroom tyrosinase: catalase activity, inhibition, and suicide inactivation     

García-Molina F  Hiner AN  Fenoll LG  Rodríguez-Lopez JN  García-Ruiz PA  García-Cánovas F  Tudela J 《Journal of agricultural and food chemistry》2005,53(9):3702-3709

Mushroom tyrosinase exhibits catalase activity with hydrogen peroxide (H(2)O(2)) as substrate. In the absence of a one-electron donor substrate, H(2)O(2) is able to act as both oxidizing and reducing substrate. The kinetic parameters V(max) and K(m) that characterize the reaction were determined from the initial rates of oxygen gas production (V(0)(O)()2) under anaerobic conditions. The reaction can start from either of the two enzyme species present under anaerobic conditions: met-tyrosinase (E(m)) and deoxy-tyrosinase (E(d)). Thus, a molecule of H(2)O(2) can reduce E(m) to E(d) via the formation of oxy-tyrosinase (E(ox)) (E(m) + H(2) <==> O(2) right harpoon over left harpoon E(ox)), E(ox) releases oxygen into the medium and is transformed into E(d), which upon binding another molecule of H(2)O(2) is oxidized to E(m). The effect of pH and the action of inhibitors have also been studied. Catalase activity is favored by increased pH, with an optimum at pH = 6.4. Inhibitors that are analogues of o-diphenol, binding to the active site coppers diaxially, do not inhibit catalase activity but do reduce diphenolase activity. However, chloride, which binds in the equatorial orientation to the protonated enzyme (E(m)H), inhibits both catalase and diphenolase activities. Suicide inactivation of the enzyme by H(2)O(2) has been demonstrated. A kinetic mechanism that is supported by the experimental results is presented and discussed.  相似文献