Dating origins polyploidy events updating java applet
We review that paradigm shift and emphasize those areas in which the ideas of Stebbins continue to propel the field forward, as well as those areas in which the field was held back; we also note new directions that plant geneticists and evolutionists are now exploring in polyploidy research.
Perhaps the most important conclusion from recent and ongoing studies of polyploidy is that, following Levin and others, polyploidy may propel a population into a new adaptive sphere given the myriad changes that accompany genome doubling.
Illustrating the broad impact of polyploidy, ancient WGD events have been documented in vertebrates (e.g., Cañestro, 2012; Braasch and Postlethwait, 2012), fungi (Kellis et al., 2004), and ciliates (Aury et al., 2006); both recent and ancient events occur extensively in plants, particularly in lineages such as the angiosperms.
In fact, researchers have long recognized that polyploidy is an inseparable part of angiosperm biology.
In the present study, we sequenced four biparentally inherited nuclear loci and three maternally inherited chloroplast fragments from all diploid and tetraploid species with the B- and C-genome types in this genus. officinalis (C-genome) were the parental progenitors of O. punctata might be better treated as a separate species (O. Recent studies have demonstrated that allopolyploidization (interspecific hybridization and genome doubling) is one of the major modes of diversification and speciation in plants, and the important source of morphological innovations. malampuzhaensis has a localized distribution in South India near the town of Malampuzha. ex Watt is the most common species and is widely distributed in south China, South and Southeast Asia, and Papua New Guinea; whereas O. Peter, is disjunctively distributed in Sri Lanka and West and East Africa (Fig. The overlapping geographical distribution and similarities in gross morphology between the diploid and tetraploid species lead further to the complexity of taxonomy and phylogeny of this group of species.
We detected at least three independent origins of three BC-genome tetraploid species. Thus, studying the origin of allopolyploids is not only the key to the understanding of consequences and mechanisms of polyploidization and crop domestication, but will facilitate also the genetic improvements for important crops and utilization of genetic resources in wild relatives of crop plants. For the diploid species, only a B-genome species (O. rhizomatis Vaughan has only been reported from Sri Lanka. However, they were unable to obtain a fully resolved phylogeny due to limited genetic markers, and failed to identify the parental donors for the tetraploid species using only nuclear markers.
Most of this work involves the large and economically important legume family ("beans"), where projects include studies addressing the origin of nodulation (symbiotic nitrogen fixation) and the study of gene families involved in cell wall synthesis, aimed at developing alfalfa (a polyploid) as a biofuels crop, particularly soybean and its wild relatives.
Soybean and, particularly, its wild relatives have been the focus of much work, developing the latter into a model system for studying natural allopolyploidy.
Previous studies showed that many valuable genes or alleles had been successfully transferred to cultivated rice from tetraploids, such as O. grandiglumis (CCDD), and have significantly increased rice yield and resistance to various diseases and pests. By illustrating the origin pattern of the BC-genome tetraploids in the rice genus, these investigations not only improve our understanding of evolutionary patterns of allopolyploid formation in the model system but also lay important foundation for utilization the wild rice germplasm in rice breeding and genetic improvement. eichingeri in the germplasm bank but confirmed to be tetraploid O. One accession of Oryza granulata with the G genome was used as an outgroup.
Polyploidy has long been considered a major force in plant evolution. Ledyard Stebbins, Jr., an architect of the Modern Synthesis, elegantly addressed a broad range of topics, from genes to chromosomes to deep phylogeny, but some of his most lasting insights came in the study of polyploidy.
Here, we review the immense impact of his work on polyploidy over more than 60 years, from his entrance into this fledgling field in the 1920s until the end of his career.
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