On the Evolution of the Genus Nicotiana

Goodspeed, T. H.

doi:10.1073/pnas.33.6.158

Cited by 18 publications

(10 citation statements)

References 4 publications

(4 reference statements)

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“…Given the mobility of seeds by wind, animals, and water, it is likely that biennial varieties or ecotypes may be transported to the southern latitudes where annualism would be beneficial. However, Nicotiana and Linaria species are not biennials (Goodspeed, 1947 ; Sutton, 1988 ; Blanco-Pastor et al, 2012 ). In addition, cT-DNA containing Linaria species from the sections Linaria and Speciosae are perennial, while other sections contain annual species.…”

Section: Possible Function Of T-dna In Plant Genomesmentioning

confidence: 99%

Horizontal gene transfer from Agrobacterium to plants

Matveeva

Лутова

2014

Front. Plant Sci.

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Most genetic engineering of plants uses Agrobacterium mediated transformation to introduce novel gene content. In nature, insertion of T-DNA in the plant genome and its subsequent transfer via sexual reproduction has been shown in several species in the genera Nicotiana and Linaria. In these natural examples of horizontal gene transfer from Agrobacterium to plants, the T-DNA donor is assumed to be a mikimopine strain of A. rhizogenes. A sequence homologous to the T-DNA of the Ri plasmid of Agrobacterium rhizogenes was found in the genome of untransformed Nicotiana glauca about 30 years ago, and was named “cellular T-DNA” (cT-DNA). It represents an imperfect inverted repeat and contains homologs of several T-DNA oncogenes (NgrolB, NgrolC, NgORF13, NgORF14) and an opine synthesis gene (Ngmis). A similar cT-DNA has also been found in other species of the genus Nicotiana. These presumably ancient homologs of T-DNA genes are still expressed, indicating that they may play a role in the evolution of these plants. Recently T-DNA has been detected and characterized in Linaria vulgaris and L. dalmatica. In Linaria vulgaris the cT-DNA is present in two copies and organized as a tandem imperfect direct repeat, containing LvORF2, LvORF3, LvORF8, LvrolA, LvrolB, LvrolC, LvORF13, LvORF14, and the Lvmis genes. All L. vulgaris and L. dalmatica plants screened contained the same T-DNA oncogenes and the mis gene. Evidence suggests that there were several independent T-DNA integration events into the genomes of these plant genera. We speculate that ancient plants transformed by A. rhizogenes might have acquired a selective advantage in competition with the parental species. Thus, the events of T-DNA insertion in the plant genome might have affected their evolution, resulting in the creation of new plant species. In this review we focus on the structure and functions of cT-DNA in Linaria and Nicotiana and discuss their possible evolutionary role.

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Section: Possible Function Of T-dna In Plant Genomesmentioning

confidence: 99%

Horizontal gene transfer from Agrobacterium to plants

Matveeva

Лутова

2014

Front. Plant Sci.

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“…Approximately 40% of Nicotiana genera are allotetraploids [18,19]. With an estimated age of 0.2 Myr [20], Nicotiana tabacum is a relatively young allotetraploid originating through the hybridization of Nicotiana sylvesteris (maternal, S-genome donor) [21,22] and Nicotiana tomentosiformis (paternal, T-genome donor) [21,23].…”

Section: Introductionmentioning

confidence: 99%

Deciphering the complex leaf transcriptome of the allotetraploid species Nicotiana tabacum: a phylogenomic perspective

Bombarely

Edwards²,

Sanchez-Tamburrino³

et al. 2012

BMC Genomics

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BackgroundPolyploidization is an important mechanism in plant evolution. By analyzing the leaf transcriptomes taken from the allotetraploid Nicotiana tabacum (tobacco) and parental genome donors, N. sylvesteris (S-Genome) and N. tomentosiformis (T-Genome), a phylogenomic approach was taken to map the fate of homeologous gene pairs in this plant.ResultsA comparison between the genes present in the leaf transcriptomes of N. tabacum and modern day representatives of its progenitor species demonstrated that only 33% of assembled transcripts could be distinguished based on their sequences. A large majority of the genes (83.6% of the non parent distinguishable and 87.2% of the phylogenetic topology analyzed clusters) expressed above background level (more than 5 reads) showed similar overall expression levels. Homeologous sequences could be identified for 968 gene clusters, and 90% (6% of all genes) of the set maintained expression of only one of the tobacco homeologs. When both homeologs were expressed, only 15% (0.5% of the total) showed evidence of differential expression, providing limited evidence of subfunctionalization. Comparing the rate of synonymous nucleotide substitution (Ks) and non-synonymous nucleotide substitution (Kn) provided limited evidence for positive selection during the evolution of tobacco since the polyploidization event took place.ConclusionsPolyploidization is a powerful mechanism for plant speciation that can occur during one generation; however millions of generations may be necessary for duplicate genes to acquire a new function. Analysis of the tobacco leaf transcriptome reveals that polyploidization, even in a young tetraploid such as tobacco, can lead to complex changes in gene expression. Gene loss and gene silencing, or subfunctionalization may explain why both homeologs are not expressed by the associated genes. With Whole Genome Duplication (WGD) events, polyploid genomes usually maintain a high percentage of gene duplicates. The data provided little evidence of preferential maintenance of gene expression from either the T- or S-genome. Additionally there was little evidence of neofunctionalization in Nicotiana tabacum suggesting it occurs at a low frequency in young polyploidy.

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“…Sometimes, however, multiple hybridizations among a specific group of species occur, causing the phylogenetic tree to become a complicated network. The process is called reticulate evolution (Goodspeed, 1947; Stebbins, 1950; for review: Rieseberg and Noyes, 1998; Marhold and Lihová, 2006). Reticulate evolution is frequently reported in plants (e.g., Rieseberg, 1991; Timme et al, 2007; Yamaji et al, 2007), and disentangling the reticulate relationships is crucial to understanding the evolution of these taxa, but it is not an easy task.…”

mentioning

confidence: 99%

Molecular evidence of reticulate evolution in the subgenus Plantago (Plantaginaceae)

Ishikawa

Yokoyama

Tsukaya

2009

American J of Botany

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Polyploidization is a frequent evolutionary event in plants that has a large influence on speciation and evolution of the genome. Molecular phylogenetic analyses of the taxonomically complex subgenus Plantago were conducted to elucidate intrasubgeneric phylogenetic relationships. A nuclear-encoding single-copy gene, SUC1 (1.0-1.8 kb), was sequenced in 24 taxa representing all five sections of the subgenus Plantago and two taxa from subgenus Coronopus as the outgroup. Fifteen known polyploids and one putative polyploid were sampled to examine polyploid origins and occurrence of reticulate evolution by cloning and sequence analysis of SUC1. Phylogenetic relationships were estimated using maximum parsimony, neighbor-joining, and Bayesian analyses. For the first time, our analysis provides a highly resolved phylogenetic tree. Subgenus Plantago formed a well-supported monophyletic clade. In contrast, alleles from polyploid species were scattered across the whole SUC1 phylogenetic tree, and some independent allopolyploids originated from hybridization between distant lineages. One reason for this taxonomic complexity can be attributed to reticulate evolution within the subgenus Plantago. Our results also suggest the possibility of two independent long-distance dispersals between the northern and southern hemispheres.

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On the Evolution of the Genus Nicotiana

Cited by 18 publications

References 4 publications

Horizontal gene transfer from Agrobacterium to plants

Horizontal gene transfer from Agrobacterium to plants

Deciphering the complex leaf transcriptome of the allotetraploid species Nicotiana tabacum: a phylogenomic perspective

Molecular evidence of reticulate evolution in the subgenus Plantago (Plantaginaceae)

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