Phylogenomic analyses and DNA barcoding development within Moraceae:
insights into genomic features, mutational hotspots, and adaptive
evolution
Abstract
Moraceae, with its seven tribes, 45 genera, and approximately 1,200
species, is of significant value in food, medicine, ecological
restoration, and as a source of industrial raw materials. However,
determination of the taxonomy and phylogeny of Moraceae species remains
challenging due to their diverse morphological features. To address this
issue, we sequenced seven complete plastomes and analyzed online
datasets for other 42 species at the tribal level within Moraceae. Our
analysis revealed that all the plastomes within this family had a
typical quadripartite structure and ranged from 159,449 to 161,478 bp in
length. Comparative plastome analyses revealed ten highly variable
regions (ndhF-rpl32, rps4-trnT, rps15-ycf1, trnC-petN, ycf1, etc.). A
total of 5,022 dispersed and tandem repeats along with 4,430 simple
sequence repeats (SSRs), were identified, highlighting their potential
for the development of molecular markers in Moraceae. While the
evolutionary rates across the various tribes of Moraceae were found to
be similar, the genes ndhK, ndhD, rps2, and rps12 displayed evidence of
positive selection. Codon usage bias was shaped by mutation and
selection, with significant natural selection observed on genes such as
clpP, ndhC, ndhI, etc. Additionally, thirteen optimal codons were
identified for 10 genes. This study confirms that the seven tribes
within the Moraceae family are monophyletic, with divergence estimated
to have occurred approximately 79.43 million years ago. This timing
coincides with the formation of modern rainforests and a burst in
angiosperm diversity towards the end of the Cretaceous period. Overall,
our study provides a robust phylogeny and a temporal framework for
further research on phylogeography and population genetics of Moraceae.
Furthermore, our genomic resources will be available for genetic
engineering and germplasm exploration within this versatile plant
family.