Selection on Cultivar Traits and Quantitative Trait Loci in Water Stressed Sunflower (Helianthus Annuus) Crop-wild Hybrids PDF Download
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Author: Birkin Richard Owart
Publisher:
ISBN:
Category : Common sunflower
Languages : en
Pages : 100
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Author: Birkin Richard Owart
Publisher:
ISBN:
Category : Common sunflower
Languages : en
Pages : 100
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Book Description
Author: Jinguo Hu
Publisher: CRC Press
ISBN: 1439840490
Category : Science
Languages : en
Pages : 374
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Book Description
The sunflower has fascinated mankind for centuries. The oilseed sunflower contributes approximately ten percent of the world's plant-derived edible oil and the confection type sunflower holds a considerable share of the directly consumed snacks market. In addition, sunflower is also grown as an ornamental for cut flowers, as well as in home ga
Author: Alexa Weiss
Publisher:
ISBN:
Category :
Languages : en
Pages : 35
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Abstract: Gene flow from agricultural crops into related wild plant populations can produce viable hybrid offspring with characteristics that differ significantly from those of their wild counterparts. Such crop-wild gene flow, especially in situations involving transgenic crops, has raised concerns about potential losses of genetic diversity, or increases in invasiveness, of wild relatives. The annual sunflower (Helianthus annuus) is an ideal species for studying crop-wild gene flow, the subsequent hybrid generations produced, and the effects on wild populations because the crop and wild types are often found in close proximity, are cross compatible, share pollinators, and are differentiated for important traits that may affect fitness, such as seed dormancy. Outside of cultivation, seeds that germinate in the fall are killed by the winter frost before reproducing, which has lead to the evolution of dormancy in wild populations; their seeds must experience a cold period before germinating in the spring. By contrast, cultivated varieties have been artificially selected to germinate immediately under favorable conditions. Consequently, the degree to which crop-wild hybrids germinate under fall conditions affects the extent to which crop genes may persist in, or introgress into, wild populations. Furthermore, the germination and dormancy characteristics of sunflower seeds, in particular, are due, in part, to the structural characteristics of their achenes (i.e., seeds and hulls). Most of these structures are maternally inherited while the genetics of the embryo involve contributions from both parents. This project determined the rates of germination and dormancy of fifteen crop-wild hybrid sunflower cross types and used microscopy to explore achene characteristics that could influence the differential germination we observed. Maternal effects (e.g., seed covering structures) had significant impacts on germination and dormancy, with crop-produced achenes germinating most readily, followed by those produced on F1 maternal plants, followed by those produced on wild plants. 3 The proportion of crop alleles (i.e., nuclear genetics of the embryo) was also important. There was a significant, positive relationship between the proportion of crop alleles and germination in the wild and F1 produced seeds. Microscopy revealed that maternal parent significantly affected achene size, embryo size, and relationships between structures and the micropylar (i.e., pointed) end of the achene. Crop produced achenes were largest and had minimal structural barriers to radicle (i.e, embryonic root) extension. F1 produced achenes were larger and had more substantial barriers which broke down quickly. Wild produced achenes were smallest and had the greatest barriers to radicle extension. Although they differed in size, structural characteristics, and germination rate, seeds produced on crop, F1, and wild maternal parents underwent the same general processes of leading up to germination. These findings suggest that crop alleles and the maternal effects associated with crop-wild hybridization can reduce dormancy, but that this reduction in dormancy may not be significant enough to prevent the introgression of crop alleles into wild populations.
Author: Arun Shanker
Publisher: BoD – Books on Demand
ISBN: 9535122509
Category : Technology & Engineering
Languages : en
Pages : 770
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Book Description
The impact of global climate change on crop production has emerged as a major research priority during the past decade. Understanding abiotic stress factors such as temperature and drought tolerance and biotic stress tolerance traits such as insect pest and pathogen resistance in combination with high yield in plants is of paramount importance to counter climate change related adverse effects on the productivity of crops. In this multi-authored book, we present synthesis of information for developing strategies to combat plant stress. Our effort here is to present a judicious mixture of basic as well as applied research outlooks so as to interest workers in all areas of plant science. We trust that the information covered in this book would bridge the much-researched area of stress in plants with the much-needed information for evolving climate-ready crop cultivars to ensure food security in the future.
Author: Keith Gardner
Publisher:
ISBN:
Category :
Languages : en
Pages : 456
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Author: Eric Von Hoeft
Publisher:
ISBN: 9781339550589
Category :
Languages : en
Pages :
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Book Description
Exotic germplasm holds considerable promise as a source of novel variation to improve agronomic characters in elite breeding pools where genetic diversity has been limited by selective sweeps in line development or crop domestication. Unfortunately, exotic germplasm typically carries a large number of unfavorable alleles that give rise to linkage drag in segregating populations, making it unsuitable for variety improvement with traditional selection methods. Linkage drag masks the detection of favorable alleles underlying complex agronomic characters by negatively impacting phenotypic performance. Consequently, the exploitation of exotic germplasm has traditionally been limited to the detection and utilization of characters controlled by relatively few alleles with dominant, co-dominant or highly additive gene action. If favorable alleles underlying complex agronomic characters could be detected in exotic germplasm sources, opportunities to exploit them in elite breeding pools through marker-assisted selection or other methods may be improved. An Advanced Inter-mated Recombinant Inbred Line (AI-RIL) population was employed to construct a genetic map and detect QTL underlying complex agronomic characters in four independent testcross populations of sunflower (Helianthus annuus). Testcross hybrids were evaluated for plant height, flowering time, seed harvest moisture, seed test weight, ring count per capitulum and grain yield. Significant QTL for each character were detected in each test cross population independently and across populations by employing the BLUP over testcross datasets. A genome-wide association study was employed to further interrogate marker-trait associations and elucidate candidate genes regulating these characters. Finally, a genomic selection model was developed to predict performance of testcross hybrids based on the estimated allele effects represented in AI-RIL genotypes and to evaluate genomic selection as a tool for the exploitation of favorable alleles from exotic germplasm sources.
Author: Yuan-Ming Zhang
Publisher: Frontiers Media SA
ISBN: 2832543693
Category : Science
Languages : en
Pages : 278
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Book Description
Genome-wide association studies (GWAS) have been widely used in the genetic dissection of complex traits. However, there are still limits in current GWAS statistics. For example, (1) almost all the existing methods do not estimate additive and dominance effects in quantitative trait nucleotide (QTN) detection; (2) the methods for detecting QTN-by-environment interaction (QEI) are not straightforward and do not estimate additive and dominance effects as well as additive-by-environment and dominance-by-environment interaction effects, leading to unreliable results; and (3) no or too simple polygenic background controls have been employed in QTN-by-QTN interaction (QQI) detection. As a result, few studies of QEI and QQI for complex traits have been reported based on multiple-environment experiments. Recently, new statistical tools, including 3VmrMLM, have been developed to address these needs in GWAS. In 3VmrMLM, all the trait-associated effects, including QTN, QEI and QQI related effects, are compressed into a single effect-related vector, while all the polygenic backgrounds are compressed into a single polygenic effect matrix. These compressed parameters can be accurately and efficiently estimated through a unified mixed model analysis. To further validate these new GWAS methods, particularly 3VmrMLM, they should be rigorously tested in real data of various plants and a wide range of other species.
Author: N. L. Jahagirdar
Publisher:
ISBN:
Category :
Languages : en
Pages : 112
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Author: Mark Kevin Mancl
Publisher:
ISBN:
Category :
Languages : en
Pages : 128
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Author: Brian Alexander Pace
Publisher:
ISBN:
Category :
Languages : en
Pages : 59
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Abstract: Although gene flow between crop and wild relatives is not a new area of study, much can still be learned through the investigation of hybrids between divergent taxon. Most crops exchange alleles with wild and weedy relatives, especially when grown in crop centers of origin. Such gene flow can result in evolutionary consequences for wild populations ranging from genetic erosion and demographic swamping to the evolution of enhanced weediness. All of these scenarios are concerning, since wild populations constitute a breeding pool in which valuable allelic diversity is stewarded and weeds already cause problems in agriculture. Helianthus annuus was domesticated in North America where its cultivated and wild forms have been known to hybridize when grown in proximity. However, cultivated sunflower and its relative, common sunflower, differ in morphology, ecological habit, and life history. For example, dormancy differs between crop and wild sunflower types since it was selected against during domestication, but has remained necessary for maintaining fitness for wild plants. Sunflower has physiological dormancy, but the strength and duration of dormancy differs between wild and crop types. Achenes resulting from hybridization between crop and wild sunflower have been shown to have reduced dormancy compared to wild achenes. Although the introgression of crop alleles into wild populations cannot occur unless the F1 generation survives to reproduce, the dormancy of later generations is important for determining if this trait could provide significant resistance to introgression. The objectives of this work were twofold: to identify how maternal parent and differing crop allele percentages each affect seed germination, dormancy, and mortality. Here, fifteen hybrid crosstypes were created on three different maternal plant types - wild F1 crop-wild hybrid, and crop. Since the pericarp and seed coat of sunflower achenes are maternal tissue, contrasting the three maternal types allowed for investigation of the impact of maternal effects in crop-wild sunflower hybrids on achene germination, dormancy, and survival. The genetic composition of these crosstypes varied from 0% to 100% crop alleles, with six intervening levels. All fifteen crosstypes were surveyed in a seed burial study, while two crosstypes were included a companion pericarp manipulation experiment. In the field experiment, three removal dates were chosen to assess hybrid seed germination, dormancy, and mortality. The contribution of crop alleles, maternal parent, and their interaction affected achene germination, dormancy, and survival. While crosstypes with higher crop allele percentages had increased early spring mortality compared to wild achenes, all crosstypes had high overwinter survival, indicating that reduced dormancy is not a complete barrier to crop allele introgression. However, hybrid achenes produced on wild maternal parents had high levels of dormancy that was comparable to wild dormancy, while crop-produced and F1-produced achenes had little to no dormancy by the last removal date, indicating that only hybrids produced on wild maternal plants will persist in the seed bank. Hybrid achenes remaining in the seed bank can be recruited in future years to backcross with wild plants or cross with remaining hybrids and may increase the risk of genetic erosion and demographic swamping.
