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En/spm-like transposons in Poaceae species: Transposase sequence variability and chromosomal distribution

2006    Altinkut, Ahu; Raskina, Olga; Nevo, Eviatar; Belyayev, Alexander

Belonging to Class II of transposable elements, En/Spm transposons are widespread in a variety of distantly related plant species. Here, we report on the sequence conservation of the transposase region from sequence analyses of En/Spm-like transposons from Poaceae species, namely Zingeria biebersteiniana, Zingeria trichopoda, Triticum monococcum, Triticum urartu, Hordeum spontaneum, and Aegilops speltoides. The transposase region of En/Spm-like transposons was cloned, sequenced, and compared with equivalent regions of Oryza and Arabidopsis from the gene bank database. Southern blot analysis indicated that the En/Spm transposon was present in low (Hordeum spontaneum, Triticum monococcum, Triticum urartu) through medium (Zingeria bieberstiana, Zingeria trichopoda) to relatively high (Aegilops speltoides) copy numbers in Poaceae species. A cytogenetic analysis of the chromosomal distribution of En/Spm transposons revealed the concurence of the chromosomal localization of the En/Spm clusters with mobile clusters of rDNA. An analysis of En/Spm-like transposase amino acid sequences was carried out to investigate sequence divergence between 5 genera - Triticum, Aegilops, Zingeria, Oryza and Arabidopsis. A distance matrix.-was generated; apparently, En/Spm-like transposase sequences shared the highest sequence homology intra-generically and, as expected, these sequences were significantly diverged from those of O. sativa and A. thaliana. A sequence comparison of En/Spin-like transposase coding regions defined that the intra-genomic complex of En/Spin-like transposons could be viewed as relatively independent, vertically transmitted, and permanently active systems inside higher plant genomes. The sequence data from this article was deposited in the EMBL/GenBank Data Libraries under the accession nos. AY707995 - AY707996 - AY707997 - AY707998 - AY707999 - AY708000 - AY708001 - AY708002 - AY708003 AY708004 - AY708005 - AY708005 - AY265312.