Development and molecular cytogenetic identification of a new wheat-rye 6RL ditelosomic addition and 1R(1B)substitution line with powderymildew resistance

Powdery mildew is a serious disease caused by Blumeria graminis f.sp.tritici(Bgt)that critically threatens the yield and quality of wheat(Triticum aestivum L.).Using effective powdery mildew resistance genes is the optimal method for controlling this disease.Against the background of high genetic homogeneity among the modern commercial cultivars that are mainly derived from conventional interbreeding,the resistance genes from wheat relatives have especially prominent advantages.Octoploid triticale,produced from common wheat and rye(Secale cereale L.)through distant hybridization,is a new synthetic species and valuable gene donor for wheat improvement.In this study,we developed the wheat-rye line YT5 through the hybridization of octaploid triticale and two wheat lines.YT5 was confirmed to be a 6RL ditelosomic addition and 1R(1B)substitution line using genomic in situ hybridization(GISH),multicolor fluorescence in situ hybridization(mc-FISH),multicolor GISH(mc-GISH)and molecular marker analysis.Genetic analysis showed that the powdery mildew resistance in YT5 was derived from the rye chromosome arm 6RL.After inoculation with different Bgt isolates at the seedling stage,YT5 had compound reaction patterns with both obvious spores and hypersensitivity,and it gradually became highly resistant until the adult-plant stage,thus showing a resistance response significantly different from the reported Pm genes from rye chromosome 6RL.YT5 also showed promising agronomic performance,so it is expected to be an elite resistance donor for wheat improvement.To promote the transfer of the chromosome arm 6RL of YT5 in marker-assisted selection(MAS)breeding,we selected and verified two 6RL-specific kompetitive allelespecific PCR(KASP)markers that can be applied to efficiently detect this chromosome arm in different wheat backgrounds.

Breeding Rice Restorer Lines with High Resistance to Bacterial Blight by Using Molecular Marker-Assisted Selection

Two bacterial blight （BB） resistance genes, Xa21 and Xa4, from IRBB24 were introduced into hybrid rice restorer line Mianhui 725, which is highly susceptible to BB, by using hybridization and molecular marker-assisted selection technology. Four homologous restorer lines were obtained through testing the R target genes with molecular markers and analyzing parental genetic background. Inoculation of the four lines and their hybrids with the specific strains of Xanthomonas oryzae pv. oryzae, P1, P6 and seven representative strains of Chinese pathotype, C Ⅰ -CⅦ, showed that all of the four lines and their hybrids were highly resistant and presented broad resistance-spectrum to BB. The hybrids of G46A / R207-2 displayed good agronomic characters and high yield potential, and R207-2 was named Shuhui 207.

Improving Blast Resistance of a Thermo-Sensitive Genic Male Sterile Rice Line GD-8S by Molecular Marker-Assisted Selection

The broad-spectrum blast resistance gene Pi-1, from donor line BL122, was introduced into a thermo-sensitive genic male sterile rice line GD-8S, which possessed good grain quality but high susceptibility to rice blast, by using backcross breeding and molecular marker-assisted selection. Five elite improved male sterile lines, RGD8S-1, RGD8S-2, RGD8S-3, RGD8S-4 and RGD8S-5, were selected based on the results of molecular marker analysis, spikelet sterility, recovery rate of genetic background and agronomic traits. Thirty-three representative blast isolates collected from Guangdong Province, China were used to inoculate the improved lines and the original line GD-8S artificially. The resistance frequencies of the improved lines ranged from 76.47% to 100%, much higher than that of the original line GD-8S （9.09%）. On the agronomic characters, there were no significant differences between the improved lines and GD-8S except for flag leaf length and panicle number per plant. The improved lines could be used for breeding hybrid rice with high blast resistance.

Breeding of R8012,a Rice Restorer Line Resistant to Blast and Bacterial Blight Through Marker-Assisted Selection

Genetic improvement is one of the most effective strategies to prevent rice from blast and bacterial blight （BB） diseases, the two most prevalent diseases jeopardizing rice production. Rice hybrids with dural resistance to blast and BB are needed for sustainable production of food. An incomplete diallele design resulted in 25 crosses between five blast and five BB resistant germplasm accessions. Only one pair of parents, DH146 ×TM487, showed polymorphism for all the markers to identify one blast resistance gene Pi25 and three BB resistance genes, Xa21, xa13 and xa5, thus it was used in the marker-assisted selection （MAS）. F2 individuals of DH146× TM487 were genotyped using flanking markers of RM3330 and sequence tagged site （STS） marker SA7 for Pi25. The resistant F2 plants with Pi25 were used for pyramiding BB resistance genes Xa21, xa13 and xa5 identified by the markers pTA248, RM264 and RM153, respectively in subsequent generations. Finally, after selection for agronomic traits and restoration ability among 12 pyramided lines, we acquired an elite restorer line, R8012 including all four target genes （Pi25＋Xa21＋xa13＋xa5）. Hybrid Zhong 9NR8012 derived from the selected line showed stronger resistance to blast and BB, and higher grain yield than the commercial checks uniformally in experimental plots, 2007 state-wide yield trial and 2008 nation-wide yield trial. This study provides a paradigmatic example to show that MAS is a practically feasible tool in effectively pyramiding multiple resistance genes. The resultant restoring line and its hybrid would play an important role in securing rice production in China.

Breeding of Maintainer Line and Sterile Line Brown Planthopper Resistant Rice Using Marker-assisted Selection

Guangxi common wild rice variety brown planthopper highly resistant introgression line HS204 was taken as antigen donor material,hybridization,backcrossing,and molecular marker-assisted selection methods were adopted,to select maintainer line and sterile line materials,so as to provide excellent material foundation for resistance breeding of hybrid rice. Through the marker-assisted selection,it obtained 4 pieces of homozygous resistance gene maintainer line intermediate materials( 100B,101B,102B and 103B),and 2 pieces of resistant sterile line materials( 100A and 103A). All 10 combinations that have testcross with highly resistant sterile 100A showed higher level of brown planthopper resistance: 100A/R2586,100A/KR838,and 100A/KR527 had high resistance level,the others had low to intermediate resistance;100A/KR527,100A/R2586,100A/Minghui 63,100A/Fuhui 838 and 100A/Gui 99 combinations had yield per plant significantly higher than the control group( Teyou 7118),increasing by 14. 45%-49. 26%. The obtained resistant lines are expected to provide a better gene source for the breeding of resistant sterile lines of hybrid rice and the obtained resistant sterile lines can be directly used in the selection of three-line hybrid rice.

Quick Approach to Construct Constrained Delaunay TIN for Line-Selection Design of Mountain Road

According to the topography of mountains, the discrete data points from map of the whole region are first subdivided into subregions with the points taken from the feature lines of ridge, valley and scarp being inserted into the map point set, and using the feature lines as the boundaries of subregions to build constrained Delaunay TIN. Such an approach has the advantages of ensuring high accuracy and fast speed of line layout.

The Application of Satellite Remote-sensing for Railway Line Selection

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Recurrent Selection for Improving Quality Characters of Male Sterile Restorer Lines of Brassica napus

[Objective] This study aimed to improve the quality characters of the male sterile restorer lines of Brassica napus by recurrent selection. [Method] The dominant male sterile alleles were used as outcross medium to be transformed with the favourable genes from thirteen materials, and finally excellent restorer materials were bred by recurrent selection. After that, the genetic diversity, genetic gains, fatty acid chain length and unsaturarion ratios of the improved populations were analyzed. [Result] The genetic diversity and genetic gains were obviously improved by the recurrent selection. Nine materials whose oil content exceeding 50% and 14 materials whose protein content exceeding 30% were acquired, and crossed with sterile lines. The comparative experiment showed that there were 11 combinations whose oil content was obviously enhanced compared with the control. [Conclusion] Recurrent selection is an effective way to improve the quality characters of the objective pop- ulations and breed favourable male sterile restorer lines of B. napus.

Combined Selection Index for New Yorkshire Dam Line with High Prolificacy

The combined selection index used in the breeding of new Yorkshire dam line with high prolificacy according to breeding objects was formulated as /：2.272E- BVNB-0.056EBVDAYS. After 5 generations breeding, the two main selected traits such as total number of born and age at 100 kg weight was 12.17 piglets/litter and 165.18 d, respectively. The genetic improvements per generates was 0.156 and -2.198, respec- tively. The breeding objects of the new Yorkshire dam line with high prolificacy were basically reached. It indicated that the methods and index could be used in pig breeding.

Mass Selection for Growth Improvement in Black Shell Line of Pacific Oyster Crassostrea gigas

The Pacific oyster,Crassostrea gigas,naturally distributing along the coast of northwest Pacific,is one of the most important bivalve species due to its high economic value and fecundity.In China,we have initiated a selective breeding program on both shell color and growth rate of C.gigas since 2010.A black shell line was obtained through four-generation family selection.In this study,mass selection for growth improvement was conducted in the sixth generation and seventh generation of black shell lines.To assess the progress of potential genetic improvement,the progeny of two generations of black shell lines were selected to evaluate their shell heights via a 450-day farming experiment.As the results,after growing for 450 days,the sixth generation and seventh generation of selected lines were 9.03% and 11.42% larger than the control lines,respectively.During the grow-out stage,the genetic gain of two generations was 8.82%±0.18% and 11.54%±0.43%,respectively;and the corresponding realized heritability was 0.45±0.04 and 0.41±0.04,respectively.These results indicated that the mass selection for shell height achieved steady progress in the two generations of C.gigas.

Development of branchless watermelon near isogenic lines by marker assisted selection

Pruning is time-consuming and laborious in watermelon cultivation,which can not meet the needs for simplified cultivation in the future.The development of branchless lines will provide important germplasms for breeding watermelon varieties and is an important method for genetic improvement.In this study,the watermelon accession,Wu Cha Zao(WCZ)is a branchless inbred line that carries the branchless gene Clbl,which was used as the donor parent to develop branchless near isogenic lines(NILs).To construct the NILs of Clbl,WCZ crossed with the normal branching watermelon inbred line WT20 which was used as the recurrent parent.The co-segregating markers dCAPS10 and Indel1 with Clbl were used for foreground selection,and a total of 108 SSR markers was selected with good polymorphism between two parental lines for background selection which had relatively uniform distribution across 11 chromosomes.Using these markers to select individuals from the BC_(1)F_(1),BC_(2)F_(1),and BC_(2)F_(2) generations,three NILs with a proportion of recurrent parent genome(PRPG)>99%were finally obtained.The lateral branch and plant height phenotypes did not significantly differ between the NILs and WCZ,indicating that the NILs of Clbl under the genetic background of WT20 has been successfully developed.These results provide ideal materials for further in-depth analysis of the genetic mechanisms of lateral branch development and ideal plant architecture breeding in watermelon.

Genetic Variation Assessed with Microsatellites in Mass Selection Lines of the Pacific Oyster (Crassostrea gigas) in China

Abstract Four successive mass selection lines of the Pacific oyster, Crassostrea gigas, selected for faster growth in breeding pro- grams in China were examined at ten polymorphic microsatellite loci to assess the level of allelic diversity and estimate the effective population size. These data were compared with those of their base population. The results showed that the genetic variation of the four generations were maintained at high levels with an average allelic richness of 18.8-20.6, and a mean expected heterozygosity of 0.902-0.921. They were not reduced compared with those of their base population. Estimated effective population sizes based on temporal variances in microsatellite frequencies were smaller to that of sex ratio-corrected broodstock count estimates. Using a rela- tively large number ofbroodstock and keeping an equal sex ratio in the broodstock each generation may have contributed to retaining the original genetic diversity and maintaining relatively large effective population size. The results obtained in this study showed that the genetic variation was not affected greatly by mass selection progress and high genetic variation still existed in the mass selection lines, suggesting that there is still potential for increasing the gains in future generations of C. gigas. The present study provided im- portant information for future genetic improvement by selective breeding, and for the design of suitable management guidelines for genetic breeding of C. gigas.

Nest box selection and reproduction of European Rollers in Central Italy: a 7-year study

Background: Changes and increased mechanisation of agricultural practices have influenced the biodiversity composition of farmland habitats and caused a decline of bird communities in many European countries. The removal of shrubs and large trees rich in natural cavities, has also led to a drastic decrease in nest site availability for cavity-nesting bird species. Nest-boxes are a common conservation tool used to improve nest-site availability, and have helped to reverse declines in many endangered bird populations. Nonetheless to maximize the results of such interventions it is crucial to know where nest-boxes should be sited. The objective of this study was to investigate the effectiveness of the nest-box program for the European Roller (Coracias garrulus) population of Lazio region (Central Italy). More specifically, we focused on what landscape features were preferred (or avoided) in the process of nest box selection and how they influenced population’s breeding parameters. Particular attention was paid to identifying potential limitations and to provide management recommendations for future interventions. Methods: Using data from 70 nest boxes sited on power lines monitored over a 7-year period (representing 140 breeding attempts), we developed probability functions to evaluate if nest box location, in terms of distance from habitat resources and habitat composition and structure, had an effect on nest box occupancy and on the main reproductive parameters. Results: Nest boxes were more likely to be occupied if they were located near arable fields and in areas characterized by a higher amount of incoming solar radiation. Higher fledging success was associated with fallow fields and with a moderate/low habitat structural complexity. Higher breeding success was associated with solar radiation and with greater distance from urban areas. Conclusions: Our results highlight the importance of specific habitat variables in influencing nest occupancy, and show which drivers primarily affect species’ reproduction and persistence over time. Siting nest boxes in habitats where occupancy rate and fledging success is higher, such as in arable and fallow fields and on south-facing slopes where solar radiation is maximised, may help to extend the suitable habitat for rollers and facilitate its local expansion.

Fault Line Selection Method Considering Grounding Fault Angle for Distribution Network

In the distribution network system with its neutral point grounding via arc suppression coil, when single-phase grounding fault occurred near zero-crossing point of the phase voltage, the inaccuracy of the line selection always existed in existing methods. According to the characteristics that transient current was different between the fault feeder and other faultless feeders, wavelet transformation was performed on data of the transient current within a power frequency cycle after the fault occurred. Based on different fault angles, wavelet energy in corresponding frequency band was chosen to compare. The result was that wavelet energy in fault feeder was the largest of all, and it was larger than sum of those in other faultless feeders, when the bus broke down, the disparity between each wavelet energy was not significant. Fault line could be selected out by the criterion above. The results of MATLAB/simulink simulation experiment indicated that this method had anti-interference capacity and was feasible.

Selection Progress of Wannan Native Chicken's Fast and Slow Feathering Lines

[Objective]This experiment aimed to establish fast and slow feathering lines from purified and rejuvenated core breeding flock. [Method] Individual and family selection were used for continuous selection from zero to the second generation. [Result]The results showed that in the fast feathering line,the average weight gain was improved by 108. 34 g per generation in roosters at the age of 20 weeks while a 54. 5 g increase was got per generation in hens. Hen housed egg production was increased from 150 to 170 at the age of 66 weeks,and the healthy rate of chicken flock was raised by 0. 7 percent. In the slow feathering line,the average weight gain was increased by 156. 6g per generation in roosters while a 38. 9 g increase was got per generation in hens,and the hen housed egg production was increased from 158 to 179 at the age of 66 weeks. [Conclusion] This research had a great significance in increasing native chicken＇s production performance and developing its market competitiveness.

Application of Genetic Rules of Quality Traits in the Selection of Watermelon Inbred Lines

On the basis of ascertaining the dominant and recessive relationship and separation ratio of quality traits such as leaf type and peel stripes,the separation of dominant and recessive traits was studied to infer whether the genes of the previous generation were homozygous.Individuals with homozygous recessive traits can be confirmed in F2 generation,and homozygous single lines with dominant traits can be confirmed in F3 generation,which speeds up the breeding process of watermelon inbred lines.

Molecular mapping of a novel wheat powdery mildew resistance gene Ml92145E8-9 and its application in wheat breeding by marker-assisted selection

Powdery mildew, caused by Blumeria graminis f. sp. tritici(Bgt), is one of the most devastating diseases of common wheat(Triticum aestivum L.). The wheat line 92145 E8-9 is immune to Bgt isolate E09. Genetic analysis reveals that the powdery mildew resistance in 92145 E8-9 is controlled by a single dominant gene, temporarily designated Ml92145 E8-9. Bulkedsegregant analysis(BSA) with simple sequence repeat(SSR) markers indicates that Ml92145 E8-9 is located on chromosome 2 AL. According to the reactions of 92145 E8-9,VPM1(Pm4 b carrier), and Lankao 906(PmLK906 carrier) to 14 Bgt isolates, the resistance spectrum of 92145 E8-9 differs from those of Pm4 b and PmLK906, both of which were previously localized to 2 AL. To test the allelism among Ml92145 E8-9, Pm4 b and PmLK906, two F2 populations of 92145 E8-9 × VPM1(Pm4 b) and 92145 E8-9 × Lankao 906(PmLK906) were developed in this study. Screening of 784 F2 progeny of 92145 E8-9 × VPM1 and 973 F2 progeny of 92145 E8-9 × Lankao 906 for Bgt isolate E09 identified 37 and 19 susceptible plants, respectively. These findings indicated that Ml92145 E8-9 is non-allelic to either Pm4 b or PmLK906. Thus, Ml92145 E8-9 is likely to be a new powdery mildew resistance gene on2 AL. New polymorphic markers were developed based on the collinearity of genomic regions of Ml92145 E8-9 with the reference sequences of the International Wheat Genome Sequencing Consortium(IWGSC). Ml92145 E8-9 was mapped to a 3.6 c M interval flanked by molecular markers Xsdauk13 and Xsdauk682. This study also developed five powdery mildew-resistant wheat lines(SDAU3561, SDAU3562, SDAU4173, SDAU4174, and SDAU4175)using flanking marker-aided selection. The markers closely linked to Ml92145 E8-9 would be useful in marker-assisted selection for wheat powdery mildew resistance breeding.

Grain selection and growth orientation of prior-β phase for Ti-6-4 during additive manufacturing:insights from a modeling perspective

The microstructure of Ti-6-4 components produced by additive manufacturing suffers from the coarse and elongated prior-β grain,which leads to a decrease of the tensile behavior and the occurrence of anisotropy.To understand and control the grain evolution,a multiscale simulation is applied to investigate the relationship between the grain selection,growth orientation,and the molten pool morphology with the different deposition layer numbers and processing parameters.The accuracy of the simulation is validated by experiments in both qualitative and quantitative ways.Results show that when the grain with unfavorable orientation loses the competitive growth with its neighbors,there will be a great chance that the blocked grain is eliminated in the following layer-and-layer deposition,which leads to the increase of the grain width.The size of the molten pool increases remarkably as the layer number increases,which lays a heavy burden on the stability of the molten pool.The analytical relationship between the molten pool morphology and the grain growth orientation is also deduced.The flat molten pool causes the grains with the <001> direction close to the building direction to have greater survival potential.Besides,decreasing the line power energy shows little effect on the stability of the molten pool and the grain growth orientation,especially when the deposited layer number is large.The revealing mechanisms will help in understanding and further controlling the grain evolution.

Selection of wide compatible restorer lines and their application in hybrid rice breeding

Since the middle of 1980’s, wide compatibility(WC) rice lines have been screened by ricebreeders in China and applied in hybrid ricebreeding program. Several WC lines such asPecos, T984, Lunhui 422, and 02428 withideal agronomic characters were identified. Weincorporated the WC gene into restorer linesby crossing these japonica WC lines with ob-tained indica lines. Some WC restorer lineswith indica-japonica medium type were ob-tained and their application value in intersub-specific hybrid rice breeding were evaluated. 1. Effect of crossing methods on selectionefficiencies of WC restorer lines

Chemical Selectivity of Laser Ion Source for on-Line Mass Separator

Thulium(Tm)atoms are resonantly ionized in a hot tube by stepwise excitations us-ing three dye lasers pumped by a series of copper vapor pulsed at a 10 kHz rate.The chemicalselectivity of the laser ion source is measured as a function of temperature of the tubes made ofTa,Nb-Zr and TaC.The chemical selectivity rises from 50 to 10000 with decreasing tube temp-erature and strongly depends on the tube material.A chemical selectivity of about 10000 withhigh efficiencies is obtained with the Nb-Zr and TaC tubes.Such a laser ion source can be usedin on-line mass separator to obtain isobarically pure ion beams.