RESUMEN
In this work the complete chloroplast DNAs of Allium paradoxum and Allium ursinum, two edible species of Allium subg. Amerallium (the first lineage), were sequenced, assembled, annotated, and compared with complete Allium plastomes of the second and third evolutionary lines from GenBank database. The A. ursinum plastome contains 90 predicted genes (81 unique) including 5 pseudogenes, while A. paradoxum has 88 predicted genes (79 unique) including 19 pseudogenes. The comparative analysis has revealed that the A. paradoxum plastome differs markedly from those of other species. Due to many deletions, the A. paradoxum plastome is the shortest of known for Allium species, being only 145,819â¯bp long. The most prominent distinctions are (1) a 4825â¯bp long local inversion that spans from the ndhE to the rpl32 gene in the small single copy region and (2) pseudogenization, or the loss of all NADH-genes. In contrast, the plastome of A. ursinum - a species from the first evolutionary line (as well as A. paradoxum) - resembles the Allium species of the second and third evolutionary lines, showing no large rearrangements or discrepancies in gene content. It is unclear yet whether only A. paradoxum was affected by some evolutionary events or its close relatives from both sect. Briseis and other sections of Amerallium were altered as well. We speculate the sunlight-intolerant, shade-loving nature of A. paradoxum and the impairment of the ndh genes in its plastome could be interrelated phenomena.
Asunto(s)
Allium/genética , Reordenamiento Génico/genética , Genes de Plantas/genética , Cebollas/genética , ADN de Cloroplastos/genética , ADN de Plantas/genética , Evolución Molecular , Genoma del Cloroplasto/genética , Genoma de Planta/genética , Filogenia , Hojas de la Planta/genética , Seudogenes/genética , Análisis de Secuencia de ADN/métodosRESUMEN
BACKGROUND: Ferns are large and underexplored group of vascular plants (~ 11 thousands species). The genomic data available by now include low coverage nuclear genomes sequences and partial sequences of mitochondrial genomes for six species and several plastid genomes. RESULTS: We characterized plastid genomes of three species of Dryopteris, which is one of the largest fern genera, using sequencing of chloroplast DNA enriched samples and performed comparative analysis with available plastomes of Polypodiales, the most species-rich group of ferns. We also sequenced the plastome of Adianthum hispidulum (Pteridaceae). Unexpectedly, we found high variability in the IR region, including duplication of rrn16 in D. blanfordii, complete loss of trnI-GAU in D. filix-mas, its pseudogenization due to the loss of an exon in D. blanfordii. Analysis of previously reported plastomes of Polypodiales demonstrated that Woodwardia unigemmata and Lepisorus clathratus have unusual insertions in the IR region. The sequence of these inserted regions has high similarity to several LSC fragments of ferns outside of Polypodiales and to spacer between tRNA-CGA and tRNA-TTT genes of mitochondrial genome of Asplenium nidus. We suggest that this reflects the ancient DNA transfer from mitochondrial to plastid genome occurred in a common ancestor of ferns. We determined the marked conservation of gene content and relative evolution rate of genes and intergenic spacers in the IRs of Polypodiales. Faster evolution of the four intergenic regions had been demonstrated (trnA- orf42, rrn16-rps12, rps7-psbA and ycf2-trnN). CONCLUSIONS: IRs of Polypodiales plastomes are dynamic, driven by such events as gene loss, duplication and putative lateral transfer from mitochondria.
Asunto(s)
Secuencias Invertidas Repetidas/genética , Plastidios/genética , Tracheophyta/genética , ADN de Plantas/genética , Genes de Plantas/genética , Genoma de Planta/genética , FilogeniaRESUMEN
Dryopteris blanfordii (C.Hope) C.Chr. is a member of the Dryopteridaceae, growing in high altitude Picea or Abies forests (2900-3500 m) in China and India. Phylogenetic relationships between D. blanfordii subsp. nigrosquamosa and closely related species of Dryopteris were investigated using a combined analysis of multiple molecular data sets (the protein-coding region of rbcL and matK genes and intergenic spacers psbA-trnH, trnP-petG, rps4-trnS, trnL-trnF and rbcL-accD). An assumption about the position of D. blanfordii subsp. nigrosquamosa within Dryopteris was made by using the Maximum Likelihood and Bayesian Inference approach and chloroplast marker sequences of Dryopteris species from GenBank. The results demonstrated that Asian taxa D. blanfordii subsp. nigrosquamosa and D. laeta as well as two American species D. arguta and D. marginalis belong to the same clade, all four of them being part of Dryopteris section Dryopteris.