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Evolutionary Dynamics of Transferred Sequences Between Organellar Genomes in Cucurbita
Ist Teil von
Journal of molecular evolution, 2019-12, Vol.87 (9-10), p.327-342
Ort / Verlag
New York: Springer US
Erscheinungsjahr
2019
Quelle
SpringerLink
Beschreibungen/Notizen
Twenty-nine DNA regions of plastid origin have been previously identified in the mitochondrial genome of
Cucurbita pepo
(pumpkin; Cucurbitaceae). Four of these regions harbor homolog sequences of
rbcL
,
matK
,
rpl20–rps12
and
trnL–trnF
, which are widely used as molecular markers for phylogenetic and phylogeographic studies. We extracted the mitochondrial copies of these regions based on the mitochondrial genome of
C. pepo
and, along with published sequences for these plastome markers from 13
Cucurbita
taxa, we performed phylogenetic molecular analyses to identify inter-organellar transfer events in the
Cucurbita
phylogeny and changes in their nucleotide substitution rates. Phylogenetic reconstruction and tree selection tests suggest that
rpl20
and
rbcL
mitochondrial paralogs arose before
Cucurbita
diversification whereas the mitochondrial
matK
and
trnL–trnF
paralogs emerged most probably later, in the mesophytic
Cucurbita
clade. Nucleotide substitution rates increased one order of magnitude in all the mitochondrial paralogs compared to their original plastid sequences. Additionally, mitochondrial
trnL–trnF
sequences obtained by PCR from nine
Cucurbita
taxa revealed higher nucleotide diversity in the mitochondrial than in the plastid copies, likely related to the higher nucleotide substitution rates in the mitochondrial region and loss of functional constraints in its tRNA genes.