Isaac-CACTA transposons: new genetic markers in maize and sorghum

CACTA is an En/Spm transposon superfamily present in high copy number in plant genomes, and Isaac is a subfamily of the CACTA superfamily. The TIR sequence of the Isaac subfamily was used for the purpose of transposon display (TD) in maize and sorghum. The Isaac TD produced 5080 amplified fragments, depending on the primer combination, and the amplification profile was highly polymorphic among maize inbred lines. Isaac TD-based phylogenetic clustering distinguished the maize inbred lines according to their lineages and was consistent with the results of phylogenetic reports derived from other marker techniques by others researchers. The Isaac TD profile proved to be highly reproducible with different brands of Taq DNA polymerases and thermocyclers. The Isaac TD was also applied to recombinant inbred lines to assess genetic segregation; we observed 4050 recordable segregation markers, depending on the primer combination. These Isaac TD markers segregated mostly as dominant markers, although, in a few cases, non-parental bands were observed in the segregating populations. In addition, the Isaac TD was very successful in the amplification of sorghum accessions. Therefore, the Isaac TD may provide another useful protocol for genetic analysis in maize and sorghum.Key words: CACTA, Isaac, transposon display, maize, sorghum.

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Characterization of High-Copy-Number Retrotransposons From the Large Genomes of the Louisiana Iris Species and Their Use as Molecular Markers

Genetics ◽

10.1093/genetics/164.2.685 ◽

2003 ◽

Vol 164 (2) ◽

pp. 685-697 ◽

Cited By ~ 1

Author(s):

Edward K Kentner ◽

Michael L Arnold ◽

Susan R Wessler

Keyword(s):

Molecular Markers ◽

Copy Number ◽

High Copy Number ◽

Marker System ◽

Transposon Display ◽

Plant Genomes ◽

Large Plant ◽

Backcross Hybrids ◽

Abundance And Distribution

Abstract The Louisiana iris species Iris brevicaulis and I. fulva are morphologically and karyotypically distinct yet frequently hybridize in nature. A group of high-copy-number TY3/gypsy-like retrotransposons was characterized from these species and used to develop molecular markers that take advantage of the abundance and distribution of these elements in the large iris genome. The copy number of these IRRE elements (for iris retroelement), is ∼1 × 105, accounting for ∼6–10% of the ∼10,000-Mb haploid Louisiana iris genome. IRRE elements are transcriptionally active in I. brevicaulis and I. fulva and their F1 and backcross hybrids. The LTRs of the elements are more variable than the coding domains and can be used to define several distinct IRRE subfamilies. Transposon display or S-SAP markers specific to two of these subfamilies have been developed and are highly polymorphic among wild-collected individuals of each species. As IRRE elements are present in each of 11 iris species tested, the marker system has the potential to provide valuable comparative data on the dynamics of retrotransposition in large plant genomes.

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