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991.
Caroline Djian-Caporalino Sergio Molinari Alain Palloix Aurelio Ciancio Ariane Fazari Nathalie Marteu Nicolas Ris Philippe Castagnone-Sereno 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(3):431-440
The emergence of virulent root-knot nematode populations, able to overcome the resistance conferred by some of the resistance
genes (R-genes) in Solanaceous crops, i.e., Mi(s) in tomato, Me(s) in pepper, may constitute a severe limitation to their use in the field. Research has been conducted to evaluate the durability
of these R-genes, by comparing the reproduction of several laboratory-selected and wild virulent Meloidogyne incognita isolates, on both susceptible and resistant tomatoes and peppers. We first show that the Me1 R-gene in pepper behaves as a robust R-gene controlling avirulent and virulent Me3, Me7 or Mi-1 isolates. Although the reproductive potential of the virulent isolates was highly variable on susceptible and resistant plants,
we also confirm that virulence is highly specific to a determined R-gene on which selection has occurred. Another significant
experimental result is the observation that a reproductive fitness cost is associated with nematode virulence against Mi-1 in tomato and Me3 and Me7 in pepper. The adaptative significance of trade-offs between selected characters and fitness-related traits, suggests that,
although the resistance can be broken, it may be preserved in some conditions if the virulent nematodes are counter-selected
in susceptible plants. All these results have important consequences for the management of plant resistance in the field. 相似文献
992.
The Balearic shearwater Puffinus mauretanicus is one of the most critically endangered seabirds in the world. The species is endemic to the Balearic archipelago, and conservation concerns are the low number of breeding pairs, the low adult survival, and the possible hybridization with a sibling species, the morphologically smaller Yelkouan shearwater (P. yelkouan). We sampled almost the entire breeding range of the species and analyzed the genetic variation at two mitochondrial DNA regions. No genetic evidence of population decline was found. Despite the observed philopatry, we detected a weak population structure mainly due to connectivity among colonies higher than expected, but also to a Pleistocene demographic expansion. Some colonies showed a high imbalance between immigration and emigration rates, suggesting spatial heterogeneity in patch quality. Genetic evidence of maternal introgression from the sibling species was reinforced, but almost only in a peripheral colony and not followed, at least to date, by the spread of the introgressed mtDNA lineages. Morphometric differences were not correlated with mtDNA haplotypes and introgression is probably due to a secondary contact between the two species several generations ago. Overall, results suggested that the very recent demographic decline in this critically endangered species has not yet decreased its genetic variability, and connectivity found among most colonies should help to reduce species extinction risk. Spreading of introgression should be monitored, but the species is not jeopardized at the moment by genetic factors and the major conservation actions should concentrate at enhancing adult survival. 相似文献
993.
Cherimoya (Anonna cherimola Mill.) is a fruit tree which originated in Peru and Ecuador and is now cultivated in several subtropical areas of the world. The characterization of cherimoya cultivars at allozyme level has been previously reported, but the geographic distribution and organization of this variation have not been fully characterized. In this study, we assessed the relationships among 206 cherimoya and four atemoya (A. cherimola ×A. squamosa) cultivars based on allozyme polymorphism. We have confirmed the genetic differences between atemoya and cherimoya cultivars, and showed that cherimoya accessions from Madeira, Bolivia and Spain form homogeneous groups of cultivars. Accessions from Chile and California form heterogeneous groups, probably due to their mixed origins. Cultivars from Peru and Ecuador showed a wide range of allelic variation, as is expected for accessions from the center of origin of this species. 相似文献
994.
Evaluation of perennial wild <Emphasis Type="Italic">Cicer</Emphasis> species for drought resistance
About 90% of chickpea (Cicer arietinum L.) in the world is grown under rainfed conditions where drought is one of the major constraints limiting its productivity.
Unlike the cultivated chickpea, wild Cicer species possesses sources of resistance to multiple stresses; we therefore evaluated perennial wild Cicer species for resistance to drought. C. anatolicum, C. microphyllum, C. montbretii, C. oxydon and C. songaricum were compared with special checks; C. echinospermum, C. pinnatifidum and C. reticulatum and five cultivated chickpeas. After the cultivated chickpeas were killed, accessions were evaluated using a 1–5 scale, where
1 = highly drought resistant (no visible drought effect and full recovery after three successive wiltings) and 5 = highly
drought susceptible (leaves and branches dried out, no recovery at all). All accessions of perennial wild Cicer species were significantly superior to those annual wild species and the cultivated chickpeas including the best drought
tolerant chickpea, ICC 4958 under drought conditions. Perennial wild Cicer species did not only recover after wilting and drying out above ground level, they also tolerated high temperatures up to
41.8°C. But, they do not cross with the cultivated chickpeas. C. anatolicum should be taken account in long term breeding programs because it has closer affinities to the first crossability group than
the others. 相似文献
995.
The study here was conducted on nearly 12,000 apricot seedlings in the Malatya Region in the Eastern part of Turkey. This
region is famous for its horticulture based mainly on apricot production and the Country's highest apricot production originates
from this region. The flower and fruit characteristics of all populations, which include apricot seedlings, in the region
were evaluated. Based on their horticultural performances, 13 genotypes were selected, of which seven were considered as apricots
served in dried form and six as in table consumption form. Among the selected genotypes, the fruit weight ranged between 28.5
and 71.19 g, soluble solids ranged between 12.7 and 26.5%, while the range in total acidity was between 0.35 and 1.80% and
fruit development period was between 87 and 183 days. To determine the selected genotypes performance in a similar environment,
they were grafted on to 4-year-old rootstocks. The results from these combinations showed that there was some decrease, especially
in fruit size and soluble solids, in the genotypes performance when compared to the results of the initial observations. Some
differences were also detected in taste, fruit shape, pit shape, fruit flesh firmness, skin and flesh colors. The dry fruit
yield was determined as 22.50–28.36% for the selected dry apricot genotypes. The dry fruit yield of all seven genotypes considered
for dry consumption were similar to ‘Hacıhaliloğlu’ and higher than ‘Canino’, which were evaluated as control cultivars. 相似文献
996.
Genetic diversity was investigated in 73 accessions of emmer wheat (Triticum dicoccon Schrank) from 11 geographical regions using a set of 29 simple-sequence repeat (SSR or microsatellite) markers, representing
at least two markers for each chromosome. The SSR primers amplified a total of 357 different alleles with an average of 12.31
alleles per locus. The number of fragments detected by each primer ranged between 6 (Xgwm1066) and 21 (Xgwm268). Null alleles were detected in nine of the 29 primers used. A high level of gene diversity index was observed. Across the
29 primers, gene diversity ranged from 0.60 (Xgwm46) to 0.94 (Xgwm655), with a mean of 0.82. There was a highly significant correlation (r=0.882; p<0.01) between gene diversity index and the number of loci, showing the number of loci per se is a strong indicator of diversity. Analysis of genetic diversity within and among eleven geographical regions revealed most
of the genetic diversity of the total sample resided within regions. The coefficient of gene differentiation (Gst = 0.27)
showed that the genetic variation within and among the 11 geographical regions was 73 and 27%, respectively. High value of
mean number of alleles per locus was found in Iran (4.86) followed by Morocco (4.10) and Armenia (4.03). On the contrary,
lower mean number of alleles per locus was detected in Yemen (2.83). The average gene diversity index across regions ranged
from 0.52 (Slovakia) to 0.67 (Morocco) with an average of 0.60. Multivariate techniques of principal component analysis and
clustering were employed to examine genetic relationship among the 73 emmer wheat accessions vis-à-vis geographical regions
of collections. The genetic distance coefficients for all possible 55 pairs of regional comparisons ranged from 0.63 (between
Iran and Armenia, Georgia and Azerbaijan, Georgia and Slovakia) to 0.97 (between Morocco and Yemen, Spain and Georgia, and
Turkey and Iran) with a mean of 0.82. From the PCA results, a two dimensional plot of PC1 versus PC2 was constructed. The
scatter plot of the first two principal components which explained altogether 27% of the total variation depicted the presence
of a clear pattern of geographical differentiation except in few cases like accessions from Caucasian region. Similar pattern
of genetic relationships among accessions was observed in cluster analysis. The study provided genetic information of emmer
wheat in relation to geographical regions of origin. The information could be utilized in crop improvement, germplasm conservation
programs, and in further investigation. 相似文献
997.
Slobodan Miko Georg Koch Saša Mesić Martina Šparica Miko Marko Šparica Polona Vreča Tadej Dolenec 《Journal of Soils and Sediments》2007,7(5):303-312
Background, Aim and Scope
Most of the cathment areas supplying water and mineral matter to the Adriatic bays with healing mud/peloids are affected by various degrees of human impact, i.e. activity that is introducing various types of contaminants to environment. The bays represent shallow marine depositional environments where organic-rich sediments accumulate. Investigations for balneological characterization of several localities along the Croatian coast have shown that these organic-rich sediments may be classified as healing mud, i.e. peloids. Healing mud due to its balneologic features is in treatment of various diseases and in improvement of the overall health conditions and general well-being. Various components of mud, particularly trace elements, could be absorbed through dermal contact. Therefore, the study of the abundance of such potentially toxic elements as As, Pb, Hg, Cd, Se, Sb, Cu, Zn in marine sediments used as healing mud is necessary in order to know their mobility and to avoid possible intoxications. 相似文献998.
A-horizons of 48 Haplic Phaeozems and Kastanozems in plain sites of the Semiarid Argentinian Pampas under three contrasting management systems (virgin bushland, permanent pasture and continuous agriculture) were studied. Morphological characteristics, organic carbon and total nitrogen levels and E4:E6 ratios were determined on the assumption that both quantity and quality of organic matter should be related to soil texture of parent materials in this region since other soil forming factors are uniform. The more intensive land use produced an averaged decrease of 7 cm in A-horizon thickness and degradation of soil structure, but little changes in color and properties of boundaries to AC horizons. In virgin soils organic carbon and nitrogen contents correlate with silt + clay fractions (r = 0,92 and 0,99, respectively), while E4:E6-ratios are related to clay contents (r = ?0.69*) confirming the strong influence of soil texture. Agricultural-management and pasture use of soils lead to dispersion of these correlations probably because of differential influence of varying intensities of land use within each management system. Soils under continuous agriculture show lower organic carbon contents than virgin soils only at clay + silt > 40%. Eragrostis curvula-pastures seems to be more effective in restoring organic matter and nitrogen levels in sandy but not in loamy soils with respect to virgin soils. This may be due to a better efficiency of E. curvula-roots in coarse than in fine textured soils to produce humificable residues than the autochthonous grass species. 相似文献
999.
We investigated C management index (CMI; an indicator of sustainability of a management system and is based on total and labile
C) and soil aggregation in medium-textured soils (silt loam and silty clay loam) under different cropping systems as follows:
maize-wheat (M-W), rice-wheat (R-W), soybean-wheat (S-W), Guinea grass, and Setaria grass. Field experiments were 6–32 years
long and were located in the wet-temperate zone of northwest Himalayas. The plant nutrients were applied through chemical
fertilizers (urea, superphosphate, and muriate of potash) with or without organic materials (FYM, wheat straw, and Lantana spp.). The content of total C (CT), labile C (CL), CMI, mean weight diameter (MWD), and aggregate porosity varied significantly under different cropping systems. The range
was 1.59 (R-W)–4.29% (Setaria) for CT, 1.23 (R-W)–3.89 mg/kg (Guinea grass) for CL, 52.09 (R-W)–129.77 (Guinea grass) for CMI, 0.90 (R-W)–5.09 (Guinea grass) for MWD, and 41.5 (R-W)–56.8% (S-W) for aggregate
porosity. Aggregate porosity was highest (56.8%) under S-W, followed by grasses (50.1–51.2%), and M/R-W (41.5–50.0%). As per
these data, (a) continuous use of N alone as urea lowered soil sustainability over control (no fertilizers); (b) use of NPK
at recommended rates improved soil productivity over control; (c) the NPK + organic amendments further improved soil sustainability;
and (d) the sustainability under different cropping systems followed the order: perennial grasses > soybean-wheat > maize-wheat
> rice-wheat. 相似文献
1000.
Jelena Petrović Snežana Dragović Ranko Dragović Milan Đorđević Mrđan Đokić Mirjana Ćujić 《Journal of Soils and Sediments》2016,16(4):1168-1175