ABSTRACT
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/Spm-like transposase coding regions defined that the intra-genomic complex of En/Spm-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.
Subject(s)
Chromosomes, Plant/genetics , DNA Transposable Elements/genetics , Poaceae/genetics , Sequence Analysis, DNA , Transposases/genetics , Amino Acid Sequence , Blotting, Southern , Chromosome Walking , Evolution, Molecular , Genome, Plant/genetics , In Situ Hybridization, Fluorescence , Molecular Sequence Data , Phylogeny , Sequence Alignment , Transposases/chemistryABSTRACT
Data are presented on the intra- and interspecific differences/similarities in chromosomal patterns of Ac-like elements (hAT family) in ecologically contrasted populations of three Triticeae species - Aegilops speltoides, Triticum urartu, and Hordeum spontaneum. Application of original computer software made it possible to precisely map transposon clusters and to link them to known chromosomal markers (rDNA sites, centromeres, and heterochromatin regions). From our data we can specify the most visible features of Ac-like elements chromosomal distribution: preferential concentration in chromosomal proximal regions; high percentage of clusters on the border between euchromatin and heterochromatin; complementary chromosomal arrangement towards En/Spm transposons (CACTA); population-specific insertions into centromeres; more differences in total cluster numbers between populations of self-pollinated species than between populations of cross-pollinated species. The application of statistical simulation (Resampling) method to analysis of data indicates that ecology may play a certain role in dynamics of Ac-like elements. Comparison of real Ayala distances, as well as real chromosomal distribution of Ac-like elements in populations of two species with different mating systems with the same but randomly simulated parameters, revealed that non-random population structure in the Mediterranean floral zone suffers and becomes chaotic in the Irano-Turanian zone.
Subject(s)
Chromosomes, Plant , Diploidy , Edible Grain/genetics , Genetics, Population , Retroelements , Base Sequence , Chromosome Mapping , DNA, Plant , Edible Grain/classification , Genome, Plant , In Situ Hybridization , RNA, Plant/genetics , RNA, Ribosomal/genetics , RNA, Ribosomal, 5S/genetics , Species SpecificityABSTRACT
We used bulked segregant analysis (BSA) to identify microsatellite markers associated with water-stress tolerance in wheat. Two DNA pools (tolerant and sensitive) were established from the selected F2 individuals of crosses between water-stress-tolerant and -sensitive wheat parental genotypes on the basis of the paraquat (PQ) tolerance, leaf size, and relative water content. All three traits were previously shown to be associated with water-stress tolerance on segregating F2 progeny of the wheat crosses used in this study. Microsatellite analysis was then performed on the established DNA pools, using 35 primer pairs that included all of the chromosome group 5 (5A, 5B, 5D) markers, to detect microsatellite fragments that were present, absent, or both in the DNA pools and their parental lines. We identified one microsatellite fragment that was present in tolerant parent wheat and the tolerant bulk but absent in the sensitive parent wheat and sensitive bulk. We then followed the segregation of this marker in the tolerant F2 individuals. Use of this marker may significantly enhance the success of selection for PQ- and water-stress-tolerant genotypes in wheat breeding programs.
