With the advent of next-generation sequencing technologies, whole-plastome data can be obtained as a byproduct of low-coverage sequencing of the plant genomic DNA. This provides an opportunity to study plastid evolution across groups, as well as testing phylogenetic relationships among taxa. Within the order Malpighiales (∼16,000 spp.), the Podostemaceae (∼300 spp.) stand out for their unique habit, living attached to rocks in fast-flowing aquatic habitats, and displaying highly modified morphologies that confound our understanding of their classification, biology, and evolution. In this study, we used genome skimming data to assemble the full plastid genome of 5 species within Podostemaceae. We analyzed our data in a comparative framework within Malpighiales to determine the structure, gene content, and rearrangements in the plastomes of the family. The Podostemaceae have one of the smallest plastid genomes reported so far for the Malpighiales, possibly due to variation in length of inverted repeat (IR) regions, gene loss, and intergenic region variation. We also detected a major inversion in the large single-copy region unique to the family. The uncommon loss or pseudogenization of
ycf1
and
ycf2
in angiosperms and in land plants in general is also found to be characteristic of Podostemaceae, but the compensatory mechanisms and implications of this and of the pseudogenization of
accD
,
rpl22
, and
clpP
and loss of
rps16
remain to be explained in this group. In addition, we estimated a phylogenetic tree among selected species in Malpighiales. Our findings indicate that the Podostemaceae are a distinct lineage with long branches that suggest faster rates of evolution in the plastome of the group, compared with other taxa in the order. This study lays the foundations for future phylogenomic studies in the family.
1
This manuscript is contextually identical with the following published paper:Lukács B.A., Mesterházy A., Vidéki R., and G. Király (2016)
AbstractEstimating the extent of biological invasions is critical in predicting the effect of exotic species. We investigated the occurrence and number of alien freshwater plants and give information on the composition of alien aquatic flora, their trend in time, invasion pathway and their invasive character.
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