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1.
S. Balasch F. Nuez G. Palomares J. Cuartero 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1984,69(1):39-45
Summary Twenty characters were measured on 60 tomato varieties cultivated in the open-air and in polyethylene plastic-house. Data were analyzed by means of principal components, factorial discriminant methods, Mahalanobis D2 distances and principal coordinate techniques. Factorial discriminant and Mahalanobis D2 distances methods, both of which require collecting data plant by plant, lead to similar conclusions as the principal components method that only requires taking data by plots. Characters that make up the principal components in both environments studied are the same, although the relative importance of each one of them varies within the principal components. By combining information supplied by multivariate analysis with the inheritance mode of characters, crossings among cultivars can be experimented with that will produce heterotic hybrids showing characters within previously established limits. 相似文献
2.
Yurena Yanes Micha? Kowalewski Carolina Castillo Julio de la Nuez 《Palaeogeography, Palaeoclimatology, Palaeoecology》2007,251(2):283-299
Quantitative estimates of time-averaging (age mixing) in gastropod shell accumulations from Quaternary (the late Pleistocene and Holocene) eolian deposits of Canary Islands were obtained by direct dating of individual gastropods obtained from exceptionally well-preserved dune and paleosol shell assemblages. A total of 203 shells of the gastropods Theba geminata and T. arinagae, representing 44 samples (= stratigraphic horizons) from 14 sections, were dated using amino acid (isoleucine) epimerization ratios calibrated with 12 radiocarbon dates. Most samples reveal a substantial variation in shell age that exceeds the error that could be generated by dating imprecision, with the mean within-sample shell age range of 6670 years and the mean standard deviation of 2920 years. Even the most conservative approach (Monte Carlo simulations with a non-sequential Bonferroni correction) indicates that at least 25% of samples must have undergone substantial time-averaging (e.g., age variations within those samples cannot be explained by dating imprecision alone). Samples vary in shell age structure, including both left-skewed (17 out of 44) and right-skewed distributions (26 out of 44) as well as age distributions with a highly variable kurtosis. Dispersion and shape of age distributions of samples do not show any notable correlation with the stratigraphic age of samples, suggesting that the structure and scale of temporal mixing is time invariant. The statistically significant multi-millennial time-averaging observed here is consistent with previous studies of shell accumulations from various depositional settings and reinforces the importance of dating numerous specimens per horizon in geochronological studies. Unlike in the case of marine samples, typified by right-skewed age distributions (attributed to an exponential-like shell loss from older age classes), many of the samples analyzed here displayed left-skewed distributions, suggestive of different dynamics of age mixing in marine versus terrestrial shell accumulations. 相似文献
3.
The generation of homozygous doubled haploid lines through induction of androgenesis is a promising alternative to the classical
inbreeding and selection programs. However, this technology is poorly developed in tomato, where doubled haploid tomato plants
have only been obtained through anther culture. Despite the fact that anther culture is routinely used in a number of economically
interesting crops, there are still many drawbacks that prevent tomato breeders from adopting this technique, and improvements
in methodology are required. One key issue is the correct identification of the optimal stage for anther excision and culture.
In this paper we characterise in vivo microsporogenesis in tomato, defining the different microspore stages and relating them to the length of the donor flower
bud. In parallel, we cultured anthers of these stages to obtain embryogenic callus, and followed the microscopic development
of the callus contained within the anther. Our data suggest that the stage with the highest response, in terms of callus generation,
is meiosis. In particular, we propose the window from metaphase I to telophase II, including tetrad cellularisation, as the
timeframe where induction can be accomplished in tomato anther cultures. 相似文献
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Ma Cortes Sánchez Mata Montaña Cámara Hurtado Salvador Roselló Ripollés Luis Galiana-Balaguer Ma Esperanza Torija Isasa Fernando Nuez Viñals 《Acta Physiologiae Plantarum》2000,22(3):250-253
Breeding programs in tomato for fresh consumption have concluded in very productive varieties/hybrids with an extraordinary
external quality. However, internal quality has not been a priority objective in these breeding programs, so present products
have a lack of important internal quality properties. Thus, internal and nutritional improvement including taste and organoleptyc
characteristics are important breeding objectives at present.
A screening trial to identify sources for internal quality improvement by increasing acid content was carried out. 12 accessions
of Lycopersicon esculentum and 8 of L. pimpinellifolium were tested with that purpose. Content in citric, malic, oxalic and fumaric acid by HPLC, soluble solids content (SSC)(1
Brix) by refractometry and total acidity by titration with NaOH were measured. Sources for high citric, malic and fumaric
acid content were found to begin those breeding programs. Results could possibly suggest an independent genetic control for
every acid. 相似文献
7.
Belén Picó Alicia Sifres Mónica Elía Ma José Díez Fernando Nuez 《Acta Physiologiae Plantarum》2000,22(3):344-350
The high variability found among Tomato yellow leaf curl virus (TYLCV) isolates from different geographical areas makes progress
in breeding for TYLCV resistance slow.
By using Agrobacterium-mediated inoculation, we have identified several new resistant sources to TYLCV within a extraordinarily variable wild Lycopersicon gene pool, collected in semidesert areas of Ecuador and Peru changed into wet by “El Nińo”. This screening assay revealed
a high susceptibility within L. esculentum and L. pennellii, but different levels of resistance within L. pimpinellifolium and L. hirsutum. Resistance level was related to the collection place, being concentrated in accessions collected in Northern Peru (Piura
province).
Agroinoculation allowed the selection of 4 Lycopersicon pimpinellifolium and 2 Lycopersicon hirsutum accessions with higher level of resistance than accessions of these species previously reported, avoiding interference due
to vector resistance mechanisms reported in both species.
These new resistance sources will be included in pyramiding strategies aimed at obtaining durable resistance to TYLCV. 相似文献
8.
J. Esteva F. Nuez 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1992,84(5-6):693-697
Summary Muskmelon yellowing disease was one of the most serious problems affecting muskmelon crops along the south-east coast of Spain throughout the 1980s. The causal agent of this disease is a virus that we call muskmelon yellows virus (MYV); MYV is transmitted by the greenhouse whitefly Trialeurodes vaporariorum Westwood. It has proven impossible to find sources of resistance to MYV within a wide collection of Spanish muskmelon landraces and exotic varieties. However, Nagata Kin Makuwa and PI 161375, lines of Asiatic origin, show tolerance to this disease. These two lines were studied together with two others (Galia and Piel de Sapo type) that are very susceptible to MYV. The crosses between them (susceptible x tolerant) and the segregant generations derived from these crosses were also investigated. The studies were carried out in two different places and years. The expression of tolerance is influenced by the environment. A parabolic type relationship exists between the average value of percentage of tolerant plants and their variation. This allowed us to quantify the expected response in the segregant generations. The results observed in these generations agreed with a simple genetic control of tolerance. This tolerance, combined with protective measures which delay the infection, can contribute notably to mitigating the effects of MYV. 相似文献
9.
The inheritance of organogenic response in melon 总被引:1,自引:0,他引:1
Previous studies have demonstrated variation in organogenic competence among plants within a population ofCucumis melo. In order to determine if leaf explant response is under genetic control, we investigated the distribution of the shoot regeneration frequency in F1 and F2 generations from parents representing extreme values forin vitro organogenic response. Results suggest a genetic model with two genes, partial dominance, independent segregation and similar effects for both genes. 相似文献
10.
R. V. Molina F. Nuez J. Cuartero M. L. Goméz-Guillamón J. Abadía 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(3):411-416
Summary Six fruit characters have been measured in 23 cultivars of Cucumis melo, representing a wide geographical range. Plants were grown both in the greenhouse and in the field. When the 23 cultivars were analyzed together, the largest component of variance was found between cultivars under both growth conditions, suggesting the existence of large genetic diversity for all the characters studied. Generally, variance between plants within cultivars was less than or equal to variance between fruits within plant. This indicates that environmental variation is the most important part of the variation within cultivars. Correlations between pairs of characters at cultivar, plant and fruit levels were calculated from the variance-covariance components. In the majority of paired traits, the correlation values indicated that genetic and environmental factors may act in the same direction. 相似文献