Comparison of the Chloroplast Genomes and Phylogenomic Analysis of
Elaeocarpaceae
Abstract
Species of Elaeocarpaceae vary, but complete chloroplast genome data and
systematic comparisons across the family are rarely reported. To
understand the variation in chloroplast sequence size and structure in
Elaeocarpaceae, the chloroplast genomes of 9 species were sequenced
using the Illumina HiSeq 2000 platform and further assembled and
annotated with Elaeocarpus japonicus and Sloanea sinensis (family
Elaeocarpaceae) as references. A phylogenomic tree was constructed based
on the complete chloroplast genomes of the 11 species representing 5
genera of Elaeocarpaceae. Chloroplast genome characteristics were
examined by using Circoletto and IRscope software. The results revealed
the following: (a) The 11 sequenced chloroplast genomes ranged in size
from 157,546 bp to 159,400 bp. (b) The chloroplast genomes of
Elaeocarpus, Sloanea, Crinodendron and Vallea lacked the rpl32 gene in
the small single-copy (SSC) region. The large single-copy (LSC) region
of the chloroplast genomes lacked the ndhK gene in Elaeocarpus, Vallea
stipularis, and Aristotelia fruticosa. The LSC region of the chloroplast
genomes lacked the infA gene in Elaeocarpus and Crinodendron patagua.
(c) Through inverted repeat (IR) expansion and contraction analysis, a
significant difference was found between the LSC/IRB and IRA/LSC
boundaries among these species. Rps3 was detected in the neighboring
regions of the LSC and IRb regions in Elaeocarpus. (d) Phylogenomic
analysis revealed that the genus Elaeocarpus is closely related to
Crinodendron patagua on an independent branch and Aristotelia fruticosa
is closely related to Vallea stipularis, forming a clade with the genus
Sloanea. Structural comparisons showed that Elaeocarpaceae diverged at
60 Mya, the genus Elaeocarpus diverged 53 Mya and that the genus Sloanea
diverged 0.44 Mya. These results provide new insight into the evolution
of the Elaeocarpaceae.