Uncovering the Genetic Architecture of Seed Weight and Size in Intermediate Wheatgrass through Linkage and Association Mapping

Intermediate wheatgrass [IWG; Thinopyrum intermedium (Host) Barkworth & D.R. Dewey subsp. intermedium] is being developed as a new perennial grain crop that has a large allohexaploid genome similar to that of wheat (Triticum aestivum L.). Breeding for increased seed weight is one of the primary goals for improving grain yield of IWG. As a new crop, however, the genetic architecture of seed weight and size has not been characterized, and selective breeding of IWG may be more intricate than wheat because of its self-incompatible mating system and perennial growth habit. Here, seed weight, seed area size, seed width, and seed length were evaluated across multiple years, in a heterogeneous breeding population comprised of 1126 genets and two clonally replicated biparental populations comprised of 172 and 265 genets. Among 10,171 DNA markers discovered using genotyping-by-sequencing (GBS) in the breeding population, 4731 markers were present in a consensus genetic map previously constructed using seven full-sib populations. Thirty-three quantitative trait loci (QTL) associated with seed weight and size were identified using association mapping (AM), of which 23 were verified using linkage mapping in the biparental populations. About 37.6% of seed weight variation in the breeding population was explained by 15 QTL, 12 of which also contributed to either seed length or seed width. When performing either phenotypic selection or genomic selection for seed weight, we observed the frequency of favorable QTL alleles were increased to \u3e46%. Thus, by combining AM and genomic selection, we can effectively select the favorable QTL alleles for seed weight and size in IWG breeding populations

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Integrating Genomics and Metabolomics to Inform Breeding for Powdery Mildew Resistance in Grapevine

University of Minnesota Ph.D. dissertation. August 2018. Major: Applied Plant Sciences. Advisors: Adrian Hegeman, James Luby. 1 computer file (PDF); x, 135 pages.Two powdery mildew resistance loci have been identified using pedigree-connected F1 mapping families at the University of Minnesota grape breeding program. A consensus linkage map of the resistant parent (MN1264) was developed for genetic mapping. The resistance loci were mapped on chromosomes 2 and 15, with additive effects accounting for over 30% phenotypic variation. Marker haplotypes, hap+chr2 and hap+chr15, were constructed to trace the inheritance of resistance loci in grandparent-parent-progeny relationships. Both hap+chr2 and hap+chr15 in the resistant F1 progeny were inherited from parent MN1264, that originated from grandparent ‘Seyval blanc’. Additionally, two microsatellites markers (i.e., UDV-015b and VViv67) were identified to be associated with hap+chr15, and can be applied for marker-assisted selection. In a follow-up study to characterize metabolic changes attributed to hap+chr2 and hap+chr15, a metabolomic experiment was conducted on whole-plant propagated grapes in a time-course response to in vivo inoculation. The use of several multivariate analyses systematically identified 52 biomarkers that were associated with hap+chr2, and 12 biomarkers with hap+chr15. In a temporal assessment of biomarkers, the discriminating metabolic changes distinguishing resistant and susceptible individuals appeared to be occurring from 24 to 48 hours after inoculation

Contributions of Reduced Susceptibility Alleles in Breeding Apple Cultivars with Durable Resistance to Fire Blight

Breeding apple cultivars with durable genetic resistance is a potential long-term solution to fire blight, a devastating bacterial disease caused by Erwinia amylovora. However, phenotyping resistance/susceptibility to fire blight is challenging due to E. amylovora strain virulence, differential host × strain interactions, quantitative host resistance, environmental influences on disease, and impacts of tree vigor on susceptibility. Inheritance of resistance/susceptibility to fire blight is complex and phenotypic information alone is insufficient to guide breeding decisions targeting resistance. Several quantitative trait loci (QTLs) associated with resistance/susceptibility to fire blight have been detected throughout the apple genome. Most resistance alleles at fire blight QTLs have been identified in wild Malus germplasm with poor fruit quality, which limits their breeding utility. Several QTLs have been identified in populations derived from cultivars and reduced-susceptibility alleles have been characterized in multiple important breeding parents. Although resistance to fire blight is an attractive target for DNA-informed breeding, relatively few trait-predictive DNA tests for breeding relevant fire blight QTLs are available. Here we discuss (1) considerations and challenges associated with phenotyping resistance/susceptibility to fire blight; (2) sources of resistance that have been identified for use as parents; and (3) our perspective on short and long-term strategies to breed apple cultivars with durable resistance to fire blight with emphasis on the potential contributions of reduced susceptibility alleles to achieve this goal

Performance study of transmit antenna selection with switch-and-examine combining over rayleigh fading

In this paper, we propose a diversity combining system with transmit antenna selection at the transmitter and switch-and-examine combining (TAS/SEC) at the receiver. This system has lower processing complexity as compared with the existing TAS systems such as TAS/maximum-ratio combining (TAS/MRC) and TAS/selection combining (TAS/SC). The performance of the TAS/SEC system with different modulation schemes over an independent and nonidentically distributed (i.n.d.) Rayleigh fading channel is investigated. The expressions of the outage probability, average output signal-to-noise ratio (SNR), and symbol error rate (SER) are derived and validated by simulation results. The performance of TAS/SEC is compared with TAS/SC in terms of the SER and the average number of branches to be estimated. It is shown that, as compared with TAS/SC, the TAS/SEC system is able to achieve a lower SER with fewer branches to be estimated

Analysis of switch diversity combining over two wave with diffuse power fading

The two wave with diffused power (TWDP) fading model is a very useful fading model characterised by two specular waves in the presence of other diffused waves and is applicable to both the Rayleigh and Rician fading channels as special cases. The performance of switch diversity with binary modulation schemes over the TWDP fading channel is examined. The four types of switch diversity investigated in this study comprise of the switch-and-stay combining, switch-and-examine combining, switch-and-examine combining with post-selection and scan-and-wait combining. The expressions of the average output signal-to-noise ratio (SNR) at the receiver and bit-error rate (BER) are derived and presented. The pre-determined SNR thresholds of the switch diversity over the TWDP fading channel are optimised to obtain the minimum BER. Analytical results are validated by simulation

Transmit antenna selection systems : A performance comparison of different types of receiver schemes

In this survey article, we compare the performance of single transmit antenna selection (TAS) systems with different kinds of receiver schemes. These systems include the TAS/switch-and-examine combining (TAS/SEC), TAS/SEC with postselection (TAS/SECPS), TAS/generalized selection combining (TAS/GSC), and TAS/output-threshold generalized selection combining (TAS/OT-GSC) systems. The performance comparisons are made in terms of the average output signal-to-noise ratio (SNR), symbol-error rate (SER), the number of channel estimates Ne, and the number of branches required for processing Np . It is shown that the TAS/SECPS and TAS/OT-GSC systems can achieve similar performance compared with the TAS/selection combining (SC) and TAS/GSC systems, respectively, with a reduced number of both channel estimates and branches required for processing when the predetermined SNR threshold is optimized

Analysis of transmit antenna selection with switch-and-examine combining with postselection at the receiver over Rayleigh fading channels

A diversity-combining system using transmit antenna selection at the transmitter and switch-and-examine combining with postselection (TAS/SECPS) at the receiver is proposed. This system has lower processing complexity as compared with the existing TAS schemes with maximal-ratio combining and selection combining (TAS/SC) at the receiver. The performance of the TAS/SECPS system with different modulation schemes over independent and nonidentically distributed Rayleigh fading channels is examined. The expressions of average output signal-to-noise ratio (SNR) and symbol error rate (SER) are derived and validated by simulation. It is shown that the proposed TAS/SECPS is able to achieve similar average output SNR and SER performance as compared with TAS/SC when the predetermined SNR threshold is optimized. Moreover, the TAS/SECPS requires less number of channel estimates

Analysis of transmit antenna selection/switch-and-examine combining over Nakagami-m fading channels

In this paper, we analyze a diversity system with the transmit antenna selection (TAS) at the transmitter and the switch-and-examine combining (SEC) at the receiver over a Nakagami-m fading channel. This system has lower complexity as compared to the TAS schemes with maximum-ratio combining and generalized selection combining at the receiver. Furthermore, the TAS/SEC scheme requires a smaller number of branch estimations compared to the TAS/SC scheme. The performance of the TAS/SEC system with binary phase-shift keying over a Nakagami-m fading channel is examined. The expressions of the average output signal-to-noise ratio and bit-error rate are derived and presented

Bit-error rate analysis of low-density parity-check codes with generalised selection combining over a Rayleigh-fading channel using Gaussian approximation

Bit-error rate (BER) expressions of generalised selection combining with low-density parity-check (LDPC) codes, using binary phase-shift keying signals, over an independent and identically distributed Rayleigh-fading channel are derived using the Gaussian approximation (GA) approach. BER results for both selection combining and maximum-ratio combining can be computed from this BER expression as special cases. The symmetry and stability conditions of both density evolution (DE) and GA analysis are also studied. The degree distribution for irregular LDPC codes is optimised using differential evolution. The theoretical results are compared with both simulation results and DE thresholds. These BER expressions allow us to achieve a significant reduction in computational complexity for analysing the system performance as compared to simulation and DE