The Roles of Mitochondrion in Intergenomic Gene Transfer in Plants: A Source and a Pool.

Nan Zhao,Yumei Wang,Jinping Hua

doi:10.3390/ijms19020547

Abstract

Intergenomic gene transfer (IGT) is continuous in the evolutionary history of plants. In this field, most studies concentrate on a few related species. Here, we look at IGT from a broader evolutionary perspective, using 24 plants. We discover many IGT events by assessing the data from nuclear, mitochondrial and chloroplast genomes. Thus, we summarize the two roles of the mitochondrion: a source and a pool. That is, the mitochondrion gives massive sequences and integrates nuclear transposons and chloroplast tRNA genes. Though the directions are opposite, lots of likenesses emerge. First, mitochondrial gene transfer is pervasive in all 24 plants. Second, gene transfer is a single event of certain shared ancestors during evolutionary divergence. Third, sequence features of homologies vary for different purposes in the donor and recipient genomes. Finally, small repeats (or micro-homologies) contribute to gene transfer by mediating recombination in the recipient genome.

Highlights

A billion years ago, a host cell engulfed a dependent bacteria, α-proteobacteria, which turned into a semi-autonomic organelle, a mitochondrion [1]
Nuclear transposons and chloroplast tRNA genes transferred into the mitochondrial genomes in most seed plants [5,7,8,9,10,11,12]
DNA sequence microhomology played an important role in chloroplast DNA inserting into the mitochondrion, which might be the microhomology-mediated break-induced replication (MMBIR) [19] or non-homologous end joining (NHEJ) [20]

Summary

Introduction

A billion years ago, a host cell engulfed a dependent bacteria, α-proteobacteria, which turned into a semi-autonomic organelle, a mitochondrion [1]. Nuclear transposons and chloroplast tRNA genes transferred into the mitochondrial genomes in most seed plants [5,7,8,9,10,11,12]. Among the nuclear-like sequences in the mitochondrial genome, the long terminal repeat retrotransposons (LTR-retro) ranked first [4,7,8,9,10,11,12]. The sequence states of chloroplast genes changed in the donor (chloroplast) and receptor (mitochondrion) genomes [16,17], which concerned their later roles [18]. DNA sequence microhomology played an important role in chloroplast DNA inserting into the mitochondrion, which might be the microhomology-mediated break-induced replication (MMBIR) [19] or non-homologous end joining (NHEJ) [20]

Methods

Results

Conclusion