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Wang Q.,Lanzhou University | Yu Q.-S.,Lanzhou University | Yu Q.-S.,Desertification Research Institute | Liu J.-Q.,Lanzhou University
Journal of Systematics and Evolution | Year: 2011

Considerable debate remains as to which DNA region should be used to barcode plants. Several different chloroplast (cp) DNA regions (rbcL, matK, and trnH. psbA) and nuclear ribosomal internal transcribed regions (ITS) have been suggested as suitable barcodes in plants. Recently, low-copy nuclear loci were also suggested to be potentially ideal barcode regions. The aim of the present study was to test the effectiveness of these proposed DNA fragments and five additional low-copy loci (CHS, DET1, COP1, PGIC1, and RPS2; comprising both coding and non-coding regions) in barcoding closely related species. We examined the divergences within and between two species of Pugionium (Brassicaceae). We failed to find any interspecific variation from three cpDNA fragments with which to discriminate the two species. However, a single base mutation in the internal transcribed spacer (ITS) could discriminate between the two species consistently. We found more variations among all individuals of the two species using each of the other five low-copy nuclear loci. However, only alleles from one locus (DET1) of the five low-copy loci related to flowering regulations was able to distinguish the sampled individuals into two species. We failed to amplify the corresponding fragments out of Brassicaceae using the designed DET1 primers. We further discussed the discrimination power of different loci due to incomplete lineage sorting, gene flow, and species-specific evolution. Our results highlight the possibility of using the nuclear ITS as a core or complementary fragment to barcode recent diverged species. © 2011 Institute of Botany, Chinese Academy of Sciences. Source

El-Amin H.K.A.,Sudan University of Science and Technology | Hamza N.B.,National Center for Research | Abuali A.I.,Desertification Research Institute
International Journal of Agricultural Research | Year: 2011

The study was carried out during two seasons 2007/08 and 2008/09, respectively. It was conducted to determine the effect of salinity stress of four concentration levels on six wheat cultivars under green house conditions and to assess their genetic diversity by using RAPD technique. Split-plot design with four replications was used. The results showed no significant differences between salinity treatments for most of the characters under study except for plant height, number of tillers plant -1 and dry shoot weight in the first season and at plant height, number of leaves plant -1, date to maturity, number of spike and grain weight/plant in second season. There were highly significant differences among varieties under salinity treatments for plant height and the number of tillers/plant in both seasons. No significant differences for interaction between varieties and salinity stress for both seasons. Six RAPD primers (OPA01, OPA03, OPA09, OPA13, OPA14 and OPA20) revealed polymorphism among the six wheat cultivars. RAPD markers were highly efficient and showed high variation among the six cultivars studied. The closer varieties genetically in the cluster behaved similarity in their response to salinity tolerance such as Candor and Debira which were genetically closely related as shown by the dendrogram and the second sisters Pohain and Wady Alnile. © 2011 Academic Journals Inc. Source

Ma S.,Leibniz Center for Agricultural Landscape Research | Ma S.,Max Planck Institute for Biogeochemistry | Ma S.,Desertification Research Institute | Churkina G.,Leibniz Center for Agricultural Landscape Research | And 2 more authors.
International Journal of Biometeorology | Year: 2012

Predicting regional and global carbon and water dynamics requires a realistic representation of vegetation phenology. Vegetation models including cropland models exist (e. g. LPJmL, Daycent, SIBcrop, ORCHIDEE-STICS, PIXGRO) but they have various limitations in predicting cropland phenological events and their responses to climate change. Here, we investigate how leaf onset and offset days of major European croplands responded to changes in climate from 1971 to 2000 using a newly developed phenological model, which solely relies on climate data. Net ecosystem exchange (NEE) data measured with eddy covariance technique at seven sites in Europe were used to adjust model parameters for wheat, barley, and rapeseed. Observational data from the International Phenology Gardens were used to corroborate modeled phenological responses to changes in climate. Enhanced vegetation index (EVI) and a crop calendar were explored as alternative predictors of leaf onset and harvest days, respectively, over a large spatial scale. In each spatial model simulation, we assumed that all European croplands were covered by only one crop type. Given this assumption, the model estimated that the leaf onset days for wheat, barley, and rapeseed in Germany advanced by 1.6, 3.4, and 3.4 days per decade, respectively, during 1961-2000. The majority of European croplands (71.4%) had an advanced mean leaf onset day for wheat, barley, and rapeseed (7.0% significant), whereas 28. 6% of European croplands had a delayed leaf onset day (0.9% significant) during 1971-2000. The trend of advanced onset days estimated by the model is similar to observations from the International Phenology Gardens in Europe. The developed phenological model can be integrated into a large-scale ecosystem model to simulate the dynamics of phenological events at different temporal and spatial scales. Crop calendars and enhanced vegetation index have substantial uncertainties in predicting phenological events of croplands. Caution should be exercised when using these data. © 2011 ISB. Source

Abuali A.I.,Desertification Research Institute | Abdelmula A.A.,University of Khartoum | Khalafall M.M.,National Center for Research
African Journal of Biotechnology | Year: 2011

The randomly amplified polymorphic DNA (RAPD) molecular markers were used to assess genetic diversity in 27 Sudanese maize genotypes. Ten primers were used, resulting in the amplification of 59 fragments, of which 53 (89.33) were polymorphic. The maximum number of fragment bands (10) were produced by the primer A-1 with 100% polymorphism, while the minimum numbers of fragments (3) were produced by the primer OPA-20. Using the unweighted pair group method with arithmetic averages (UPGMA) method, the genetic associations obtained showed three distinct heterotic groups. The high rate of polymorphism between genotypes revealed by RAPD markers indicated that the method is efficient to analyze genetic divergence and can be used to establish consistent heterotic groups between maize genotypes. ©2011 Academic Journals. Source

Wang Q.,Sichuan University | Abbott R.J.,University of St. Andrews | Yu Q.-S.,Desertification Research Institute | Lin K.,Chinese Academy of Sciences | Liu J.-Q.,Sichuan University
New Phytologist | Year: 2013

Pleistocene climate change has had an important effect in shaping intraspecific genetic variation in many species; however, its role in driving speciation is less clear. We examined the possibility of a Pleistocene origin of the only two representatives of the genus Pugionium (Brassicaceae), Pugionium cornutum and Pugionium dolabratum, which occupy different desert habitats in northwest China. We surveyed sequence variation for internal transcribed spacer (ITS), three chloroplast (cp) DNA fragments, and eight low-copy nuclear genes among individuals sampled from 11 populations of each species across their geographic ranges. One ITS mutation distinguished the two species, whereas mutations in cpDNA and the eight low-copy nuclear gene sequences were not species-specific. Although interspecific divergence varied greatly among nuclear gene sequences, in each case divergence was estimated to have occurred within the Pleistocene when deserts expanded in northwest China. Our findings point to the importance of Pleistocene climate change, in this case an increase in aridity, as a cause of speciation in Pugionium as a result of divergence in different habitats that formed in association with the expansion of deserts in China. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust. Source

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