Data from: Plastome sequencing of ten nonmodel crop species uncovers a large insertion of mitochondrial DNA in cashew

In plant evolution, intracellular gene transfer (IGT) is a prevalent,
ongoing process. While nuclear and mitochondrial genomes
are known to integrate foreign DNA via IGT and horizontal
gene transfer (HGT), plastid genomes (plastomes) have resisted
foreign DNA incorporation and only recently has IGT been uncovered
in the plastomes of a few land plants. In this study, we
completed plastome sequences for l0 crop species and describe
a number of structural features including variation in gene and
intron content, inversions, and expansion and contraction of the
inverted repeat (IR). We identified a putative rpl22 in cinnamon
(Cinnamomum verum J. Presl) and other sequenced Lauraceae
and an apparent functional transfer of rpl23 to the nucleus of
quinoa (Chenopodium quinoa Willd.). In the orchard tree cashew
(Anacardium occidentale L.), we report the insertion of an ~6.7-
kb fragment of mitochondrial DNA into the plastome IR. BLASTn
analyses returned high identity hits to mitogenome sequences
including an intact ccmB open reading frame. Using three
plastome markers for five species of Anacardium, we generated
a phylogeny to investigate the distribution and timing of the insertion.
Four species share the insertion, suggesting that this event
occurred <20 million yr ago in a single clade in the genus. Our
study extends the observation of mitochondrial to plastome IGT
to include long-lived tree species. While previous studies have
suggested possible mechanisms facilitating IGT to the plastome,
more examples of this phenomenon, along with more complete
mitogenome sequences, will be required before a common, or
variable, mechanism can be elucidated.