HEC-HMS模型和NAM模型在降雨径流模拟中的应用研究

HEC-HMS(Hydrologic Engineering Center-Hydrologic Modeling System)模型是半分布式水文模型,NAM(Nedbør-Afstrømnings-Model)模型是集总式概念性模型,通过对两种模型计算原理和模型架构及参数组成进行对比,并选取滁河沙河集子流域的5场日径流进行模拟,通过模拟结果对两种模型在降雨径流模拟性能上进行比较研究。研究结果表明,两种模型均有较好的模拟效果,预报的径流深均在许可误差范围内。两种模型在降雨径流模拟过程中均存在一定的局限性,HEC-HMS模型计算功能强大,部分参数能直接反映流域的具体特性,但是其建模过程较繁琐,且内部的观测值难以进行检验,NAM建模过程简便,所需参数较少且物理意义明确,但是模型计算过程忽略了流域的空间变异及产流的空间分布。

Mapping of a new gene for brown planthopper resistance in cultivated rice introgressed from Oryza eichingeri

Wild rice species is an important source of useful genes for cultivated rice improvement Some accessions of Oryza eichingeri (In = 24, CC) from Africa confer strong resistance to brown planthopper (BPH), whitebacked planthopper (WBPH) and bacterial blight (KB). In the present study, restriction fragments length polymorphism (RFLP) and simple sequence repeats (SSR) analysis were performed on disomic backcross plants between Oryza saliva (2n =24, AA) and O. eichingeri in order to identify the presence of O, eichingeri segments and further to localize BPH-resistant gene. In the introgression lines, 1-6 O. eichingeri segments were detected on rice chromosomes 1, 2, 6, or/and 10. The dominant BPH resistant gene, tentatively named Bphl3(t), was mapped to chromosome 2, being 6.1 and 5.5 cM away from two microsatellite markers RM240 and RM250, respectively. The transfer and localization of this gene from O. eichingeri will contribute to the improvement of BPH resistance in cultivated rice.

QTL analysis of the rice seedling cold tolerance in a double haploid population derived from anther culture of a hybrid between indica and japonica rice

A doubled haploid population, derived from anther culture of F hybrid between a typical indica cv. and a japonica cv. has been used to investigate the seedling cold tolerance (SCT) in growth cabinet. By dynamically analyzing every day’s survival percentages of the parents and DH lines under 7-d cold plus 9-d normal temperature condition, the guantitative trait loci (QTLs) for SCT have been mapped based on a molecular linkage map constructed from this population. The results show that two parents had significant differences in SCT and the segregation of SCT in DH lines was basically a continuous distribution with most serious injury on the 6th d of the cold treatment. A total of 4 QTLs for SCT have been identified on chromosomes 1, 2, 3 and 4 respectively. The additive effects of qSCT-1, qSCT-2 and qSCT-3 have been contributed by the japonica ev JX17, but that of qSCT-4 has been contributed by the indica cv ZYQ8. The mechanism of SCT seems complicated since the above 4 QTLs detected at different stages

QTL analysis of rice low temperature germinability

A double haploid population, derived from anther culture of F, hybrid between a typical indica and a japonica (ZYQ8/JX17), has been used to investigate the low temperature germinability (LTG) at 15℃. The low temperature germinability of two parents was significantly different. In 6-11 d, the germination percentage of ZYQ8 was higher than that of JX17. In 12-16 d, the germination percentage of JX17 was higher than that of ZYQ8. The quantitative trait loci (QTLs) of every day for low temperature germinabilityhave been mapped based on a molecular linkage map constructed from this population. In 8-11 d, qLTG-9 was identified in C397B-RZ617B on chromosome 9, the additive effect was positive, showing that, the allele from JX17 could increase low temperature germinability. In 12-16 d, qLTG-4 was mapped between RG908 and CT563 on chromosome 4, the additive effect was negative, showing that the allele from ZYQ8 could increase low temperature germinability. These two QTLs were detected at different stages,

Identification of an AFLP marker linked to the stripe rust resistance gene Yr10 in wheat

AFLP analysis of near-isogenic lines of the stripe rust resistance gene Yr10 was carried out with 6 Pst I -primers and 10 Taq I -primers with the donor parent of Yr1O gene as the check. A total of about 4200 distinguishable bands were amplified, of which 5 were stable. The genetic linkage of the 5 polymorphic DNA fragments with the target gene were tested preliminarily on a segregating F2 population derived from a cross between the gene donor parent 'Moro' and susceptible cultivar 'Mingxian 169'. The DNA fragment PT0502 was found closely linked to the Yr10 gene and cloned and sequenced. Based on the sequence specific primers for PCR were designed and synthesized. Genetic linkage analysis with 195 segregating F2 plants indicated that the genetic distance was 0.5 cM between the main product SC200 fragment produced by PCR with the primers and the Yr10 gene. The primers can be used to detect the Yr10 gene quickly, effectively and exactly.

Identification of quantitative trait loci affecting tolerance to low phosphorus in rice (Oryza Sativa L.)

Phosphorus (P)-deficiency in rice (Oryza. Sativa. L) may cause yield reductions. This research has been conducted to map quantitative trait loci (QTLs) for tolerance to low phosphorus stress in a doubled haploid (DH) population. By using the linkage map of this population, the OTLs for relative dry weight, relative P content and relative P utilization efficiency have been located. The results indicate that one RFLP marker located on chromosome 6 is closely associated with relative root dry weight, relative shoot dry weight and relative total dry weight, which explain 24.9%, 20.5% and 25.2% of the total phenotypic variations, respectively. Two QTLs affect relative P uptake content, which account for 20.7% of the total phenotypic variations. One micro-effect QTL has been found to be associated with relative P utilization efficiency. It is suggested that the P uptake efficiency is more associated with P efficiency. Among the secondary physiological indices of P uptake efficiency, the root dry weight is

Fine mapping of the rice bacterial blight resistance gene Xa-4 and its co-segregation marker

An F2 population developed from the Xa-4 near isogenic lines, IR24 and IRBB4, was used for fine mapping of the rice bacterial blight resistance gene, Xa-4. Some restriction fragment length polymorphism （RFLP） markers on the high-density map constructed by Harushima et al. and the amplified DMA fragments homologous to the conserved domains of plant disease resistance （R） genes were used to construct the genetic linkage map around the gene Xa-4 by scoring susceptible individuals in the population. Xa-4 was mapped between the RFLP marker G181 and the polymerase chain reaction （PCR） marker M55. The R gene homologous fragment marker RS13 was found co-segregating with Xa-4 by analyzing all the plants in the population. This result opened an approach to map-based cloning of this gene, and marker RS13 can be applied to molecular marker-assisted selection of Xa-4 in rice breeding programs.

Adapting rice anther culture to gene transformation and RNA interference

Anther culture offers a rapid method of generating homozygous lines for breeding pro- gram and genetic analysis.To produce homozygous transgenic lines of rice(Oryza sativa L.)in one step,we developed an efficient protocol of anther-callus-based transformation mediated by Agro- bacterium after optimizing several factors influencing efficient transformation,including callus induc- tion and Agrobacterium density for co-cultivation.Using this protocol,we obtained 145 independent green transformants from five cultivars of japonica rice by transformation with a binary vector pCXK1301 bearing the rice gene,Xa21 for resistance to bacterial blight,of which 140 were further confirmed by PCR and Southern hybridization analysis,including haploids(32.1%),diploids(62.1%) and mixoploids(7.5%).Fifteen diploids were found to be doubled haploids,which accounted for 10.7%of the total positive lines.Finally,by including 28 from colchicine induced or spontaneous dip- loidization of haploids later after transformation,a total of 43 doubled haploids(30.7%)of Xa21 transgenic lines were obtained.We also generated two RNAi transgenic haploids of the rice Os- MADS2 gene,a putative redundant gene of OsMADS4 based on their sequence similarity,to inves- tigate its possible roles in rice flower development by this method.Flowers from the two OsMADS2 RNAi transgenic haploids displayed obvious homeotic alternations,in which lodicules were trans- formed into palea/lemma-like tissues,whereas identities of other floral organs were maintained.The phenotypic alternations were proved to result from specific transcriptional suppression of OsMADS2 gene by the introduced RNAi transgene.The results confirmed that OsMADS2 is involved in lodicule development of rice flower and functionally redundant with OsMADS4 gene.Our results demonstrated that rice anther culture could be adapted to gene transformation and RNAi analysis in rice.

Optical mapping of a rice BAC clone using restriction endonuclease and imaging with fluorescent microscopy at single molecule level

A method of constructing restriction map by optical mapping and single molecule fluorescent microscopy is described. DNA molecules were aligned and adsorbed on a glass coverslip surface by a modified 'molecular combing' technique, and then the surface-immobilized DNAs were cleaved in situ with a restriction endonuclease. Individual DNA molecules digested by the endonuclease EcoR I were observable with fluorescent microscopy. Using optical mapping, a physical map of a rice bacterial artificial chro-mosome clone was constructed. This method will facilitate genomic mapping and tracing the dynamic process in real time at a single molecule level with fluorescence microscopy.

Efficient selection of homozy-gous lines of hybrid rice restorer with the transgene Xa21 using test cross and PCR

The homozygous restorer lines with a single copy of the transgene Xa21 have been obtained from the progenies of transgenic Minghui63 and Yanhui559 plants through PCR marker-assisted selection and test cross. These homozygoustransgenic restorer lines can be used to breed hybrid rice with high resistance to bacterial leaf blight.