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Evolution of Weediness and Invasiveness: Charting the Course for Weed Genomics
- C. Neal Stewart, Jr., Patrick J. Tranel, David P. Horvath, James V. Anderson, Loren H. Rieseberg, James H. Westwood, Carol A. Mallory-Smith, Maria L. Zapiola, Katrina M. Dlugosch
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- Journal:
- Weed Science / Volume 57 / Issue 5 / October 2009
- Published online by Cambridge University Press:
- 20 January 2017, pp. 451-462
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- Article
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The genetic basis of weedy and invasive traits and their evolution remain poorly understood, but genomic approaches offer tremendous promise for elucidating these important features of weed biology. However, the genomic tools and resources available for weed research are currently meager compared with those available for many crops. Because genomic methodologies are becoming increasingly accessible and less expensive, the time is ripe for weed scientists to incorporate these methods into their research programs. One example is next-generation sequencing technology, which has the advantage of enhancing the sequencing output from the transcriptome of a weedy plant at a reduced cost. Successful implementation of these approaches will require collaborative efforts that focus resources on common goals and bring together expertise in weed science, molecular biology, plant physiology, and bioinformatics. We outline how these large-scale genomic programs can aid both our understanding of the biology of weedy and invasive plants and our success at managing these species in agriculture. The judicious selection of species for developing weed genomics programs is needed, and we offer up choices, but no Arabidopsis-like model species exists in the world of weeds. We outline the roadmap for creating a powerful synergy of weed science and genomics, given well-placed effort and resources.
7 - Evolution of the nuclear genome of ferns and lycophytes
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- By Takuya Nakazato, Department of Biology, Indiana University, Bloomington, IN 47405, USA, Michael S. Barker, Department of Biology, Indiana University, Bloomington, IN 47405, USA, Loren H. Rieseberg, Department of Botany, University of British Columbia, Vancouver V6T 1Z4, Canada and Department of Biology, Indiana University, Bloomington, IN 47405, USA, Gerald J. Gastony, Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Edited by Tom A. Ranker, University of Colorado, Boulder, Christopher H. Haufler, University of Kansas
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- Book:
- Biology and Evolution of Ferns and Lycophytes
- Published online:
- 11 August 2009
- Print publication:
- 19 June 2008, pp 175-198
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Summary
Introduction
Analyses of gene expression and function, genetic networks, population polymorphisms, and genome organization at the whole genome level have enabled research on previously intractable questions (reviewed in Wolfe and Li, 2003). Among plant lineages, genomic approaches have been most widely applied in the angiosperms, where significant resources have been developed. Angiosperm studies utilizing genome scale analyses have made several important advances, including the identification of an extensive history of genome duplications (Blanc et al., 2003; Schlueter et al., 2004; Cui et al., 2006), progress in understanding flower development and evolution (Doust et al., 2005; Whibley et al., 2006), characterization of the genetics underlying speciation and adaptation (Bradshaw and Schemske, 2003; Rieseberg et al., 2003; Lai et al., 2005; Eyre-Walker, 2006), the identification and mapping of recombination hot spots (Drouaud et al., 2006), and the discovery and role of microRNAs (Bartel and Bartel, 2003; Bartel, 2004). Genomic analyses will undoubtedly continue to provide tests of longstanding questions and offer novel perspectives in biology. For example, modern genomic analyses are capable of explaining the origin of the exceptionally high chromosome numbers of homosporous ferns and lycophytes, a result that will shed light on eukaryotic genome organization and evolution.
Although there are rich biological and taxonomic resources for ferns and lycophytes, the genomics of these seed-free plants is still in its infancy, and the tools necessary for genomic studies lag behind those available for seed plants. The first homosporous fern linkage map was published only recently (Nakazato et al., 2006), whereas a large number of linkage maps for seed plants have accumulated since the 1980s
Plant hybridization
- LOREN H. RIESEBERG, SHANNA E. CARNEY
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- Journal:
- The New Phytologist / Volume 140 / Issue 4 / December 1998
- Published online by Cambridge University Press:
- 01 December 1998, pp. 599-624
- Print publication:
- December 1998
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Summary 599
I. Introduction 599
II. Concepts and terminology 600
III. Historical background 600
IV. Studies of experimental hybrids 601
1. Isolating mechanisms 601
2. Prezygotic barriers 602
(a) Gametic barriers to hybridization 602
3. Postzygotic barriers 603
(a) Chromosomal rearrangements 604
(b) Genic sterility or inviability 604
4. Hybrid vigour 605
5. Introgression 606
6. Hybrid speciation 607
V. Experimental manipulations of natural hybrid populations 609
1. Hybrid-zone formation 610
2. Pollinator-mediated selection 610
3. Habitat selection 612
VI. The biology of different classes of hybrids 612
1. Character expression 613
(a) Morphological characters 613
(b) Chemical characters 613
(c) Molecular characters 613
2. The fitness of different classes of hybrids 614
(a) The importance of variance 614
(b) Estimating hybrid fitness 615
3. Interactions with parasites and herbivores 616
4. Patterns of mating 617
(a) Outcrossing rate 617
(b) Hybridization frequency 618
(c) Mate choice 618
VII. Conclusions and future research 619
Acknowledgements 620
References 620
Most studies of plant hybridization are concerned with documenting its occurrence in different plant groups. Although these descriptive, historical studies are important, the majority of recent advances in our understanding of the process of hybridization are derived from a growing body of experimental microevolutionary studies. Analyses of artificially synthesized hybrids in the laboratory or glasshouse have demonstrated the importance of gametic selection as a prezygotic isolating barrier; the complex genetic basis of hybrid sterility, inviability and breakdown; and the critical role of fertility selection in hybrid speciation. Experimental manipulations of natural hybrid zones have provided critical information that cannot be obtained in the glasshouse, such as the evolutionary conditions under which hybrid zones are formed and the effects of habitat and pollinator-mediated selection on hybrid-zone structure and dynamics. Experimental studies also have contributed to a better understanding of the biology of different classes of hybrids. Analyses of morphological character expression, for example, have revealed transgressive segregation in the majority of later-generation hybrids. Other studies have documented a high degree of variability in fitness among different hybrid genotypes and the rapid response of such fitness to selection – evidence that hybridization need not be an evolutionary dead end. However, a full accounting of the role of hybridization in adaptive evolution and speciation will probably require the integration of experimental and historical approaches.