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901.
Susheel Verma Jawahar L. Karihaloo Shailesh K. Tiwari Rani Magotra Awtar K. Koul 《Genetic Resources and Crop Evolution》2007,54(2):221-229
Eremostachys superba Royle ex Benth. (Lamiaceae) has undergone a severe decline in population size since its discovery in the North-western Himalayas
in late 19th century. One hundred and seventy-two plants from six populations in the Indian states of Uttar Pradesh and Jammu
& Kashmir, located between 0.45 km and 455.72 km apart from each other were evaluated for RAPD polymorphism. Sixteen random
primers generated 92 bands overall, 77 of which were polymorphic. Shannon’s index of genetic diversity within populations
(H
o) ranged between 0.305 and 0.421; the average within-population diversity (H
pop) was 0.389; and the total species diversity (H
sp) was 0.478. The population from Mohand (representing the type locality) had the fewest plants, at 18, and was genetically
the most depauperate. Among the other populations, ranging in size between 52 and 1,022 individuals, no relation between population
size and genetic diversity was evident. It is suggested that these six populations represent relics of a larger, extended
population, in which the presence of perennating rootstocks has helped preserve historic patterns of genetic diversity. AMOVA
revealed that 83.01% of the variation exists within populations, which was consistent with earlier studies on the reproductive
biology of E. superba, which indicated this species is predominantly allogamous. FST distances between all populations were significant, indicating
geographic differentiation despite some of them being closely separated. Habitat restoration and protection from indiscriminate
harvesting are proposed as primary strategies for conserving E. superba. Rejuvenation of the Mohand population through intrapopulation crossing between plants bearing diverse molecular phenotypes
is also suggested. 相似文献
902.
Xiao-Ping Jia Yun-Su Shi Yan-Cun Song Guo-Ying Wang Tian-Yu Wang Yu Li 《Genetic Resources and Crop Evolution》2007,54(2):233-236
The development of EST-SSR in foxtail millet (Setaria italica) for polymorphism and transferability study was reported here. From 1213 EST sequences, 30 SSRs were obtained and primers
were designed for 26 SSRs. Among them, four pairs of SSR primers amplified polymorphic products in 12 foxtail millet cultivars
and one accession of Setaria viridis, a wild relative of foxtail millet, with 10 alleles detected for the four loci and 2.5 alleles per locus. In addition, ten
SSR markers could be transferred to other nine Gramineae species. The putative functions of 11 ESTs containing polymorphic
and transferable SSRs were also identified. 相似文献
903.
In industrial areas, heavy metals may accumulate in forest soil organic horizons, affecting soil microorganisms and causing
changes in the chemical composition of the accumulated organic matter. The objectives of this study were to test the ability
of near-infrared spectroscopy (NIRS) to detect heavy metal effects on the chemical composition of forest soil O horizons and
to test whether NIRS may be used to quantitatively determine total and exchangeable concentrations of Zn and Pb (Znt, Pbt, Znex, Pbex) and other chemical and microbial properties in forest soil O horizons polluted with heavy metals. The samples of O horizons
(n = 79) were analyzed for organic C (Corg), total N and S (Nt, St), Znt, Pbt, Znex, Pbex, basal respiration (BR), microbial biomass (Cmic) and Cmic-to-Corg ratio. Spectra of the samples were recorded in the Vis-NIR range (400–2,500 nm). To detect heavy-metal-induced changes in
the chemical composition of O horizons principal components (PC1–PC7) based on the spectral data were regressed against Znt + Pbt values. A modified partial least squares method was used to develop calibration models for prediction of various chemical
and microbial properties of the samples from their spectra. Regression analysis revealed a significant relationship between
PC3 and PC5 (r = −0.27 and −0.34, respectively) and Znt + Pbt values, indicating an effect of heavy metal pollution on the spectral properties of the O horizons and thus on their chemical
composition. For quantitative estimations, the best calibration model was obtained for Corg-to-Nt ratio (r = 0.98). The models for Corg, Nt, and microbial properties were satisfactory but less accurate. NIRS failed to accurately predict St, Corg-to-St, Znt, Pbt, Znex, and Pbex. 相似文献
904.
Louise Willemen Xavier Scheldeman Víctor Soto Cabellos Simón Rafael Salazar Luigi Guarino 《Genetic Resources and Crop Evolution》2007,54(7):1599-1612
This study evaluates quantitatively the suitability of the use of site-specific socio-economic and environmental data as indicators
to rapidly assess patterns of diversity and genetic erosion risk in cassava. Socio-economic data as well as farmers’ estimation
of genetic erosion were collected in the study area, the Ucayali region of the Peruvian Amazon, through interviews with 285
cassava farmers in 50 communities, while diversity was assessed based on agromorphological characterization of 295 cassava
accessions. Using multivariate regression analyses, 50 and 45% of the variation in respectively diversity and genetic erosion
estimation could be explained by a selected set of socio-economic and environmental indicators. In both regression models
four out of the total of 38 variables proved to contribute significantly (at p < 0.10 level). Additionally, the study revealed that farmers are a good direct source of information on the diversity present
at community level, which can contribute to the development of methodologies to assess diversity more rapidly. The results
of this study are valuable for the development of models to rapidly assess diversity dynamics in large areas. 相似文献
905.
Verónica Nilda Ispizúa Irma Rosana Guma Sergio Feingold Andrea Martina Clausen 《Genetic Resources and Crop Evolution》2007,54(8):1833-1848
Andean potato varieties are cultivated in the northwest of Argentina and constitute the most important staple food for the
local farmers. The genetic diversity of 155 accessions conserved at the Genebank of Balcarce (INTA) was tested using four
microsatellites. Three commercial potato varieties of Tuberosum group and one accession of Curtilobum group were used as outgroups.
The presence of bands was scored for each microsatellite and for each accession and the data were analysed by principal coordinate
analysis. The polymorphism information content was obtained for each molecular marker from banding patterns. Analysis of molecular
variance was carried out with a variable number of accessions for each landrace, from different departments and sites within
departments. More than one genotype was detected in the majority of the potato landraces. Some accessions within each landrace
did not differentiate. AMOVA revealed that most of the genetic variation occurred among sites within departments and among
local varieties. These findings are discussed considering the agricultural practices carried out in the Andean farming system. 相似文献
906.
N. P. S. Dhillon R. Ranjana Kuldeep Singh I. Eduardo A. J. Monforte M. Pitrat N. K. Dhillon P. P. Singh 《Genetic Resources and Crop Evolution》2007,54(6):1267-1283
Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was
assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance
and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in
plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew,
Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation
and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions
of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference
accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon
germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base
of melon germplasm available with the scientific community.
N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors. 相似文献
907.
Li Huang Wenfeng Tan Fan Liu Hongqing Hu Qiaoyun Huang 《Journal of Soils and Sediments》2007,7(4):240-246
Background, Aims, and Scope Hydroxy interlayered vermiculite (HIV) and vermiculite are commonly referred to as 1.4 nm minerals. In the subtropical soils
of central China, the concentration of vermiculites decreased while that of HIVs increased gradually from north to south as
the intensity of soil formation or eluviation increases in the same direction. The cutans in these soils closely interact
with air, roots, microbes, water and dissolved ions in soils. Cutans may therefore be expected to exert an important influence
on the formation of 1.4 nm minerals relative to the matrix soils. However, little is known about the transformation of 1.4
nm minerals in Alfisols in central China. Here, we investigate the compositional differences of 1.4 nm minerals in cutans
and matrix soils, and the probable transformation of vermiculite to HIV or vice versa when sodium citrate and sodium acetate
are added to matrix Alfisols.
Methods Cutans and matrix soils were separated from three soils in the northern subtropical zone in China. The samples were analyzed
for Fe, Mn, exchangeable cations, organic matter(O.M.), pH, and clay minerals. To 10 mL of matrix soil, suspensions containing
about 250 mg (oven-dry weight) of clay was added with 5 mL of 0.4 mol/dm3 or 2 mol/dm3 of sodium citrate or sodium acetate solution and 5 mL of 0.2 mol/dm3 mixed solutions of CaCl2, Mg(NO3)2 and KCl. After its pH was adjusted to 6.0, the mixture was ‘incubated’ for 120 or 210 days (more than one season or half
a year) during which period it was shaken for 1 hour every day. The clay mineral composition of the samples was determined
after incubation.
Results Both vermiculites and HIVs were present in matrix soils, but only vermiculties were detected in cutans. The addition of organic
ligands (citrate and acetate) promoted the transformation of HIV to vermiculite. This transformation was obvious for the matrix
soils that had been incubated with 0.5 mol/dm3 sodium citrate for 210 days while sodium acetate was less effective in this regard. The promoting effect of organic ligands
is dependent on type and concentration as well as incubation time. This would suggest the reverse transformation occurred
in the formation of cutans compared with a vermiculite-to-HIV transformation in the subtropical soils of central China from
north to south.
Discussion The position and environment of cutans in the B horizon together with the pH, organic matter and exchangeable base status
in cutans seem conducive to the co-existence of vermiculite and HIV in the soils, but only vermiculite is found in cutans.
The transformation of HIV to vermiculite in incubation experiments could be divided into two steps: 1) Cheluviation of organic
matter to the interlayer hydroxy-aluminums from HIVs. 2) Rebasification of hydrated cations into the interlayers of vermiculites.
Conclusions The clay minerals in cutans can interact with organic ligands and nutrient elements excreted by roots. Under conditions of
frequent wetting and drying and high pH, and when the concentrations of exchangeable bases, iron-manganese oxides, clays,
and organic matter are high, the exchangeable cations can be incorporated into the interlayers of HIV, thereby promoting the
partial transformation of HIV to vermiculite in rhizosphere soils.
Recommendations and Perspectives Cutan is at the interface of material and energy exchange involved in physical, chemical and biochemical reactions in the
rhizosphere. These factors strongly affect the compositions of cutans. HIVs in (upper or adjacent) matrix soils may transform
to vermiculites during cutan formation in these special soil environments.
ESS-Submission Editor: Jizheng (Jim) He (jzhe@rcees.ac.cn) 相似文献
908.
Genetic diversity of seven Rhus L. species was assessed using random amplified polymorphic DNA (RAPDs) markers. Initially, 90 primers were screened, of which 25 produced reproducible amplification products. These primers generated a total of 296 bands, with an average of 11.8 bands per primer. Out of 296 bands scored, 236 (80%) were polymorphic and 62 (20%) were monomorphic. Primers OPC-05 and OPD-05 generated 100% polymorphic bands. The resolving power of primers ranged from 9.4 to 26.8. Similarity matrix values ranged from 0.45 to 0.63. The dendrogram generated using Unweighted Pair Group Method using Arithmetic Averages (UPGMA) grouped all the species of Rhus in one major group with two sister groups, whilst R. pyroides Burch. and R. dentata Thunb. were outliers. R. gerrardii (Harv. ex Engl.) Diels, R. glauca Thunb. and R. pentheri Zahlbr. constituted one sister group, while R. natalensis Bernh. ex C. Krauss and R. gueinzii Sond. were included in the other. The degree of genetic diversity observed between seven species of Rhus with RAPD markers suggest that this approach could be used for studying the phylogeny of the genus. 相似文献
909.
Weixing Liu Wenhua Xu Yi Han Changhui Wang Shiqiang Wan 《Biology and Fertility of Soils》2007,44(2):259-268
Temporal dynamics of microbial biomass and respiration of soil and their responses to topography, burning, N fertilization,
and their interactions were determined in a temperate steppe in northern China. Soil microbial indices showed strong temporal
variability over the growing season. Soil microbial biomass C (MBC) and N (MBN) were 14.8 and 11.5% greater in the lower than
upper slope, respectively. However, the percentage of organic C present as MBC and the percentage of total N present as MBN
were 16.9 and 26.2% higher in the upper than lower slope, respectively. Neither microbial respiration (MR) nor metabolic quotient
(qCO2) was affected by topography. Both MBC and MBN were increased by burning, on average, by 29.8 and 14.2% over the growing season,
and MR and qCO2 tended to reduce depending on the sampling date, especially in August. Burning stimulated the percentage of organic C present
as MBC and the percentage of total N present as MBN in the upper slope, but did not change these two parameters in the lower
slope. No effects of N fertilization on soil microbial indices were observed in the first growing season after the treatment.
Further research is needed to study the long-term relationships between changes in soil microbial diversity and activity and
plant community in response to burning and N fertilization. 相似文献
910.
Ulrich Förstner 《Journal of Soils and Sediments》2007,7(4):270-270