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Submitted to: DNA Sequence
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/11/2003 Publication Date: 8/1/2003 Citation: Taliercio, E., Ulloa, M. 2003. The DNA Sequence of a Gypsy Element from Gossypium hirsutum L. and Characterization of Gypsy Elements in Three Gossypium Species. DNA Sequence. 14(4):319-325. Interpretive Summary: Retrotransposons are mobile genetic elements that comprise a large portion of many plant genomes and can be mutatgenic. Cotton is the result of a cross between two related species of Gossypium and such crosses have been observed to activate retroelements that can alter the genome of the resultant hybrid. Therefore one type of retroelement was characterized in cotton and its progenitors. A complete putative retrotransposons was isolated from cotton and completely sequenced. It was determined to be an inactive element but was used to show that similar sequences were present in both progenitors. Cotton did not appear to have more copies of this type of element than one of its progenitors. Analysis of 75 unique isolates of a portion of the retrotransposons from cotton and its progenitors did not reveal any evidence that this element was amplified in cotton. There was, however, a correlation between the copy number of these types of retroelements and total genome size. The progenitor species with the smallest genome had the fewest of this family of retroelements. Evaluation of these sequences revealed a new member of this family of retrotransposons. New species of Gossypium are used to introduce new agronomically important traits into cotton. Information about retrotransposons in cotton will provide tools to monitor activity of retrotransposons in crosses of cotton with other species and eliminate lines that have deleterious amplifications of retrotransposons. Additionally, the characterization of retroelements in cotton can be used to help map the cotton genome to identify agronomically important traits such as disease resistance, yield and fiber quality. Technical Abstract: The authors identify and characterize a gypsy element from three cotton species. The cotton species examined are Gossypium hirsutum, G. herbaceum and G. raimondii. Gypsy elements are related to a class of mobile genetic elements that can cause mutations in plants and often comprise a large portion of a plant's genome. These mobile elements have been shown to be active in wide crosses of rice. The example of rice is particularly pertinent to G. hirsutum, which is the result of an ancient cross between G. herbaceum and G. raimondii. This complete gypsy element is flanked by long terminal repeats of 295 nt and has a gene order comparable to all other gypsy-type mobile elements. The new cotton gypsy element is approximately 5998 nt long and has stop codons in all reading frames indicating it is not active. DNA blot analysis indicates that there is a homolog of this sequence in all three Gossypium species investigated. Analysis of a portion of gypsy elements in the three cotton species indicate that this particular family of elements was not amplified in G. hirsutum compared to the other species, but was less active in G. raimondii which has a much smaller genome than either G. hirsutum or G. herbaceum. Additionally a new gypsy element was identified that was common to G. hirsutum and G. Raimondii. This information may be used in mapping the genome of upland cotton. |
