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Evolution of genome size in Brassicaceae.
Ann Bot 2005; 95(1):229-35AB

Abstract

BACKGROUND AND AIMS

Brassicaceae, with nearly 340 genera and more than 3350 species, anchors the low range of angiosperm genome sizes. The relatively narrow range of DNA content (0.16 pg < 1C < 1.95 pg) was maintained in spite of extensive chromosomal change. The aim of this study was to erect a cytological and molecular phylogenetic framework for a selected subset of the Brassicacae, and use this as a template to examine genome size evolution in Brassicaceae.

METHODS

DNA contents were determined by flow cytometry and chromosomes were counted for 34 species of the family Brassicaceae and for ten Arabidopsis thaliana ecotypes. The amplified and sequenced ITS region for 23 taxa (plus six other taxa with known ITS sequences) were aligned and used to infer evolutionary relationship by parsimony analysis.

KEY RESULTS

DNA content in the species studied ranged over 8-fold (1C = 0.16-1.31 pg), and 4.4-fold (1C = 0.16-0.71 pg) excluding allotetraploid Brassica species. The 1C DNA contents of ten Arabidopsis thaliana ecotypes showed little variation, ranging from 0.16 pg to 0.17 pg.

CONCLUSIONS

The tree roots at an ancestral genome size of approximately 1x = 0.2 pg. Arabidopsis thaliana (1C = 0.16 pg; approximately 157 Mbp) has the smallest genome size in Brassicaceae studied here and apparently represents an evolutionary decrease in genome size. Two other branches that represent probable evolutionary decreases in genome size terminate in Lepidium virginicum and Brassica rapa. Branches in the phylogenetic tree that represent probable evolutionary increases in genome size terminate in Arabidopsis halleri, A. lyrata, Arabis hirsuta, Capsella rubella, Caulanthus heterophyllus, Crucihimalaya, Lepidium sativum, Sisymbrium and Thlaspi arvense. Branches within one clade containing Brassica were identified that represent two ancient ploidy events (2x to 4x and 4x to 6x) that were predicted from published comparative mapping studies.

Authors+Show Affiliations

Department of Entomology, Texas A and M University, College Station, TX 77843, USA. spencerj@tamu.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

15596470

Citation

Johnston, J Spencer, et al. "Evolution of Genome Size in Brassicaceae." Annals of Botany, vol. 95, no. 1, 2005, pp. 229-35.
Johnston JS, Pepper AE, Hall AE, et al. Evolution of genome size in Brassicaceae. Ann Bot. 2005;95(1):229-35.
Johnston, J. S., Pepper, A. E., Hall, A. E., Chen, Z. J., Hodnett, G., Drabek, J., ... Price, H. J. (2005). Evolution of genome size in Brassicaceae. Annals of Botany, 95(1), pp. 229-35.
Johnston JS, et al. Evolution of Genome Size in Brassicaceae. Ann Bot. 2005;95(1):229-35. PubMed PMID: 15596470.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evolution of genome size in Brassicaceae. AU - Johnston,J Spencer, AU - Pepper,Alan E, AU - Hall,Anne E, AU - Chen,Z Jeffrey, AU - Hodnett,George, AU - Drabek,Janice, AU - Lopez,Rebecca, AU - Price,H James, PY - 2004/12/15/pubmed PY - 2005/5/14/medline PY - 2004/12/15/entrez SP - 229 EP - 35 JF - Annals of botany JO - Ann. Bot. VL - 95 IS - 1 N2 - BACKGROUND AND AIMS: Brassicaceae, with nearly 340 genera and more than 3350 species, anchors the low range of angiosperm genome sizes. The relatively narrow range of DNA content (0.16 pg < 1C < 1.95 pg) was maintained in spite of extensive chromosomal change. The aim of this study was to erect a cytological and molecular phylogenetic framework for a selected subset of the Brassicacae, and use this as a template to examine genome size evolution in Brassicaceae. METHODS: DNA contents were determined by flow cytometry and chromosomes were counted for 34 species of the family Brassicaceae and for ten Arabidopsis thaliana ecotypes. The amplified and sequenced ITS region for 23 taxa (plus six other taxa with known ITS sequences) were aligned and used to infer evolutionary relationship by parsimony analysis. KEY RESULTS: DNA content in the species studied ranged over 8-fold (1C = 0.16-1.31 pg), and 4.4-fold (1C = 0.16-0.71 pg) excluding allotetraploid Brassica species. The 1C DNA contents of ten Arabidopsis thaliana ecotypes showed little variation, ranging from 0.16 pg to 0.17 pg. CONCLUSIONS: The tree roots at an ancestral genome size of approximately 1x = 0.2 pg. Arabidopsis thaliana (1C = 0.16 pg; approximately 157 Mbp) has the smallest genome size in Brassicaceae studied here and apparently represents an evolutionary decrease in genome size. Two other branches that represent probable evolutionary decreases in genome size terminate in Lepidium virginicum and Brassica rapa. Branches in the phylogenetic tree that represent probable evolutionary increases in genome size terminate in Arabidopsis halleri, A. lyrata, Arabis hirsuta, Capsella rubella, Caulanthus heterophyllus, Crucihimalaya, Lepidium sativum, Sisymbrium and Thlaspi arvense. Branches within one clade containing Brassica were identified that represent two ancient ploidy events (2x to 4x and 4x to 6x) that were predicted from published comparative mapping studies. SN - 0305-7364 UR - https://www.unboundmedicine.com/medline/citation/15596470/Evolution_of_genome_size_in_Brassicaceae_ L2 - https://academic.oup.com/aob/article-lookup/doi/10.1093/aob/mci016 DB - PRIME DP - Unbound Medicine ER -