Genomic prediction of yield performance among single-cross maize hybrids using a partial diallel cross design

Genomic prediction(GP)in plant breeding has the potential to predict and identify the best-performing hybrids based on the genotypes of their parental lines.In a GP experiment,34 elite inbred lines were selected to make 285 single-cross hybrids in a partial-diallel cross design.These lines represented a mini-core collection of Chinese maize germplasm and comprised 18 inbred lines from the Stiff Stalk heterotic group and 16 inbred lines from the Non-Stiff Stalk heterotic group.The parents were genotyped by sequencing and the 285 hybrids were phenotyped for nine yield and yield-related traits at two locations in the summer sowing area(SUS)and three locations in the spring sowing area(SPS)in the main maizeproducing regions of China.Multiple GP models were employed to assess the accuracy of trait prediction in the hybrids.By ten-fold cross-validation,the prediction accuracies of yield performance of the hybrids estimated by the genomic best linear unbiased prediction(GBLUP)model in SUS and SPS were 0.51 and 0.46,respectively.The prediction accuracies of the remaining yield-related traits estimated with GBLUP ranged from 0.49 to 0.86 and from 0.53 to 0.89 in SUS and SPS,respectively.When additive,dominance,epistasis effects,genotype-by-environment interaction,and multi-trait effects were incorporated into the prediction model,the prediction accuracy of hybrid yield performance was improved.The ratio of training to testing population and size of training population optimal for yield prediction were determined.Multiple prediction models can improve prediction accuracy in hybrid breeding.

Relationship Between Hybrid Performance and Genetic Diversity Based on SSRs and ISSRs in Brassica napus L.

To investigate the relationship between genetic distance (GD) and hybrid performance, two types of molecular markers, microsatellites (simple sequence repeats, SSRs) and intro-simple sequence repeats (ISSRs), were employed to detect the genetic diversity of 3 double low self-incompatible lines and 22 male parental varieties of Brassica napus from different geographical origins. Hybrids were produced in a NCⅡ mating design by hand-pollination. The result indicated that 25 parental varieties (lines) could be divided into six groups by Un-weighted Pair Group Mathematics Average (UPGMA) clustering based on GDs. SI-1300 and SI-1320 could be singly clustered into one group, respectively. Varieties from China could be separated into another group, SI-1310 and varieties from foreign countries could be separated into other three groups. The grouping was generally consistent with parental pedigrees and geographical origins. Significant differences in yield, quality and phenological period traits were observed among these parent groups. Although hybrid yield/plant showed significantly positive correlation with genetic distance based on SSR and ISSR markers, but the determination coefficient was low. It appeared to be unsuitable for using the genetic distance based on SSR and ISSR markers to predict heterosis and hybrid performance in Brassica napus.

Thermodynamic Performance of Three-Terminal Hybrid Quantum Dot Thermoelectric Devices

We propose four different models of three-terminal quantum dot thermoelectric devices. From general thermodynamic laws, we examine the rew;rsible efficiencies of the four different models. Based on the master equation, the expressions for the efficiency and power output are derived and the corresponding working regions are determined. Moreover, we particularly analyze the performance of a three-terminal hybrid quantum dot refrigerator. The performance characteristic curves and the optimal performance parameters are obtained. Finally, we discuss the influence of the nonradiative effects on the optimal performance parameters in detail.

Nanojunctions Contributing to High Performance Thermoelectric ZnO-Based Inorganic-Organic Hybrids

Organic-inorganic nanojunctions can result in a selective scattering of charge carrier depending on their energy, which leads to a simultaneous increase in the Seebeck coefficient S and the power factor. In this work, the nanojunction is successfully employed at the organic-inorganic semiconductor interface of polyparaphenylene （PPP） and Zn1-xAgxO nanoparticles through the sol-gel method. The presence of nanoinclusions PPP in Zno.gAgoa 0 matrix is found to be effective in improving the figure of merit （ZT） by the dual effects of an increase in the power factor consistent with the heterojunetion effect and a reduction in thermal conductivity. Zno.gAgo.10/0.1 wt% PPP exhibits a maximum figure of merit, i.e., ZT= 0.22.

A differentially methylated region of the ZmCCT10 promoter affects flowering time in hybrid maize

Flowering time(FT) is a key maize domestication trait, variation in which allows maize to grow in a wide range of latitudes. Although previous studies have investigated the genetic control of FT-related traits per se, few studies of FT hybrid performance have been published. We characterized the genomic architecture associated with hybrid performance for FT in a hybrid panel by testcrossing Chang 7–2 with 328Ye478 × Qi319 recombinant inbred lines(RILs). We identified 11 quantitative trait loci(QTL) for hybrid performance in FT-related traits, including a major QTL qFH10 that controls hybrid performance and heterosis in a summer maize-growing region. However, this locus acts in regulating FT traits per se only in a spring maize-growing region. We validated ZmCCT10 as a candidate gene for qFH10 and found that differences between hybrids and their parental lines in DNA methylation in the differentially methylated region(DMR, –700 to –1520) of the ZmCCT10 promoter affected gene expression pattern and thereby FT in the summer maize-growing region.

Heterosis effect for larval performance of fall armyworm interstrain hybrids

Spodoptera frugiperda,also known as fall armyworm(FAW),is an invasive crop pest that can feed on a variety of host plants,posing a serious threat to food security.There are two sympatric strains of FAW that are morphologically identical but described with different food preferences:the“rice strain”(SfR)and the“corn strain”(SfC).A few genetic loci exist to identify these two strains.Mitochondrial and Z-chromosome-linked haplotypes are the most used,but the biggest part of the genome displays little polymorphism between strains that could explain their adaptation to different plants.We have previously observed consistent transcription differences between the strains in both laboratory and natural populations.Therefore,we wonder if there are effects from host-strain-associated loci,maternally or paternally inherited,on FAW performance that could explain the divergence between the two FAW strains.To test this hypothesis,we first produced two F1 hybrid generations(SfR♀×SfC♂,SfC♀×SfR♂).These reciprocal hybrids should be heterozygous for all chromosomes except for the maternally inherited mitochondrial and sexual W chromosomes.To evaluate whether plant preference is determined by these genetic loci,we cultivated the two hybrids and the two parental strains in triplicate on an artificial diet and recorded several phenotypic traits such as weight over time,survival rate,emerging rate,developmental time,and sex ratio.Then,the same performance experiment was carried out on corn plants.Surprisingly,on the artificial diet,the two hybrid genotypes were both more performant than the two parental strains in terms of survival rate,pupal emerging rate,and developmental time,whereas they were intermediate to the inbred parental strains in pupal weight.On the corn plant diet,both hybrid genotypes outperformed the two parental strains in larval weight.Although these asymmetrical results revealed that mitochondrial or sex-linked haplotypes alone cannot explain the performance differences,they suggested a heterosis effect in FAW.A reduction of the female number for the CR genotype and the decreased F1 offspring reproduction in both hybrids suggested the possibility of Haldane's rule,which might be explained by the dominance model.

Relationship Between Differential Gene Expression and Heterosis During Ear Development in Maize (Zea mays L.)

Maize （Zea raays L.） is one of the most important crops because of the remarkable properties of its hybrid, which is responsible for the high commercial value of hybrid maize. The genetic basis of heterosis （hybrid vigor） is not well understood. A differential display technique was performed to identify genes with differential expression across twelve maize inbred lines and thirty-three hybrids during ear development. An incomplete diallel design was used to investigate the relationship between the global framework of differential gene expression and heterosis. It was found that the genes belonging to MONO pattern （i.e., genes expressed in both parental lines and in hybrid） was the highest in percentage among the total five patterns and illustrated that the properties of differentially expressed genes are not entirely responsible for heterosis. Furthermore,a larger number of differentially expressed genes in hybrid, which serves as a major reservoir for generating novel phenotypes that exhibit heterosis of certain agronomic traits during early development and differentiation of maize ear. Moreover, there were some silent genesin hybrids that are responsible for the arrest or abortion of spikelets and for the increase in kernels weight.

Modeling the influence of phenotypic plasticity on maize hybrid performance

Phenotypic plasticity,the ability of an individual to alter its phenotype in response to changes in the environment,has been proposed as a target for breeding crop varieties with high environmental fitness.Here,we used phenotypic and genotypic data from multiple maize(Zea mays L.)populations to mathematically model phenotypic plasticity in response to the environment(PPRE)in inbred and hybrid lines.PPRE can be simply described by a linear model in which the two main parameters,intercept a and slope b,reflect two classes of genes responsive to endogenous(class A)and exogenous(class B)signals that coordinate plant development.Together,class A and class B genes contribute to the phenotypic plasticity of an individual in response to the environment.We also made connections between phenotypic plasticity and hybrid performance or general combining ability(GCA)of yield using 30 F_(1) hybrid populations generated by crossing the same maternal line with 30 paternal lines from different maize heterotic groups.We show that the parameters a and b from two given parental lines must be concordant to reach an ideal GCA of F_(1) yield.We hypothesize that coordinated regulation of the two classes of genes in the F_(1) hybrid genome is the basis for high GCA.Based on this theory,we built a series of predictive models to evaluate GCA in silico between parental lines of different heterotic groups.

Performance evaluation of a WDM/OCDM based hybrid optical switch utilizing efficient resource allocation

A hybrid optical switch （HOS） with physical layer of wavelength division multiplexing and optical code division multiplexing （WDM/OCDM） scheme is proposed. An additional feature to the HOS than optical cross connect （OXC） is that the controller can process requests for both circuit establishment and burst scheduling. In our study, the measurement criteria of HOS are the blocking probability, probability of error, and probability of outage. To simplify the analysis, no distinction is made between a circuit in progress and a burst in progress. Moreover, a minimum fit （MinF） resource allocation strategy is applied in order to increase the bandwidth efficiency and control the multiplexing interference of the OCDM. A 2D Markov model for the HOS is presented using the MinF strategy. Numerical results reveal that the code parameters and the resource allocation strategy greatly affect the performance. Certain periority can be achieved by assigning shorter codes to high periority users and longer codes to low periority users. Also, the probability of error and outage are reduced bv aonling the MinF strategy.

SCStore： Managing Scientific Computing Packages for Hybrid System with Containers

Managing software packages in a scientific computing environment is a challenging task, especially in the case of heterogeneous systems. It is error prone when installing and updating software packages in a sophisticated computing environment. Testing and performance evaluation in an on-the-fly manner is also a troublesome task for a production system. In this paper, we discuss a package management scheme based on containers. The newly developed method can ease the maintenance complexity and reduce human mistakes. We can benefit from the self-containing and isolation features of container technologies for maintaining the software packages among intricately connected clusters. By deploying the Super Computing application Strore（SCStore） over the WAN connected world-largest clusters, it proved that it can greatly reduce the effort for maintaining the consistency of software environment and bring benefit to achieve automation.