Reference genome sequences of two cultivated allotetraploid cottons, Gossypium hirsutum and Gossypium barbadense.

Allotetraploid cotton species (Gossypium hirsutum and Gossypium barbadense) have long been cultivated worldwide for natural renewable textile fibers. The draft genome sequences of both species are available but they are highly fragmented and incomplete1,2,3,4. Here we report reference-grade genome assemblies and annotations for G. hirsutum accession Texas Marker-1 (TM-1) and G. barbadense accession 3–79 by integrating single-molecule real-time sequencing, BioNano optical mapping and high-throughput chromosome conformation capture techniques. Compared with previous assembled draft genomes1,3, these genome sequences show considerable improvements in contiguity and completeness for regions with high content of repeats such as centromeres. Comparative genomics analyses identify extensive structural variations that probably occurred after polyploidization, highlighted by large paracentric/pericentric inversions in 14 chromosomes. We constructed an introgression line population to introduce favorable chromosome segments from G. barbadense to G. hirsutum, allowing us to identify 13 quantitative trait loci associated with superior fiber quality. These resources will accelerate evolutionary and functional genomic studies in cotton and inform future breeding programs for fiber improvement

Lithogeochemical characteristics and metallogenic mechanism of the Hetaoshu rich-PGE magmatic sulfide deposit in the Xiaoguanhe region, Panxi

The Hetaoshu rich-PGE magmatic sulfide deposit is located in Xiaoguanhe area, Huili County, the ore-bearing lithofaciy is a mafic-ultramafic intrusion, which is one of the magma sulfide deposits rich in PGE content in the Emeishan Large Igneous Province (ELIP). This paper will provide a basic study on major elements, trace elements and platinum-group elements for various rocks and ores in the intrusion, and we discussed the characteristic of magma source and parental magma, the degree of partial melting of the mantle, and the process of rock-forming and ore-forming. The study show that the Hetaoshu mafic-ultramafic rocks are products of tectonic-magmatic activity in the ELIP and belong to tholeiitic evolution trend, which have the similar characteristics with Emeishan basalts from the ratio of the trace elements. Primitive mantle-normalized patterns of Ni-Cu-PGE are similar with Jinbaoshan with the low ratio of Pd/Ir (1.5 similar to 13. 1), relative to the Ni and Cu, PGE is undepletion, relative to Os, Ir,, Ru and Rh, Pt and Pd are enrichment. By estimating, the parental magma was produced by fractional crystallization from picritic-like magmas generated by relatively high degrees (about 20. 17%) of partial melting of an OIB-type mantle source, with the composition of 11. 93% in MgO, 49. 88% in SiO2, 2. 61% in TiO2 and 13. 71% in FeOT. In comparison with several types of Ni-Cu-PGE magmatic sulfide deposits from the composition of PGE and sulfide segregation in the Xiaoguanhe area, the enrichment of platinum group elements and low of Cu/ Pd of the Hetaoshu deposit is similar with Jinbaoshan, this kind of characteristic indicated that, the sulfide might segregate from the PGE undepleted picritic-like magmas. By analysis of the mechanism of diagenesis and mineralization, in the early stage of magmatic evolution, the accumulation of mafic minerals which represented as olivine (about 12. 7%) occurred after the picritic-like magmas intruded deep-level chamber, and formed high-Mg basalt magma; affected by factors such as temperature reduction and crustal contamination, the partial residual high-Mg basaltic magma have undergone segregation (R = 2000 similar to 50000) when they flowed from deep to high level chamber; then the sulfide melt mixed with olivine, which form in magma conduit. Finally, under the impacts of tectonic compression, the olivine-sulfide mixtures formed rich-PGE intrusion by accumulation in high-level chamber, its highly variable R factor are corresponding with the wide range of PGE contents

An Optimal Model for Water Resources Risk Hedging Based on Water Option Trading

The uncertainty of forecasted runoffs brings risks of water shortages to water users in the intake area of long-distance water transfer projects, and the uncertainty of spot market prices may cause them to buy water at high prices. In order to hedge these risks, this paper proposes a risk hedging model for decision-making in water option trading from the viewpoint of water users. With the objective of maximizing the expected revenue of water users, the proposed model was solved by an analytical method and an optimal water option strategy was obtained for the users. The proposed model is applied to an intake area of an inter-basin water transfer project in China. The results show that the proposed water option trading model can provide water users with an optimal option strategy. The optimal options trading strategy can effectively reduce the risk caused by the uncertainties of forecasted runoffs and water prices. We also explored the influence of the uncertainty degree of the forecasted runoffs and water price on the option trading strategy. The results show that the expected revenue of water users increases as the variances of the errors of forecasted runoffs and water prices increase