Chlorosis	loss of the green coloration of the plant leaves due to chlorophyll deficiency.
Cytonuclear Linkage Disequilibrium (cnLD)	represents the non-random association of nuclear and cytoplasmic alleles and is influenced by several factors, such as the inheritance pattern of organellar genome, hybridization, selective forces, mating system… Its evolutionary significance will depend on its magnitude and how stable CN interactions are [73,96].
Effective size (Ne)	the effective size of a population is a parameter that is used in population genetics to quantify the effect of genetic drift on the genetic diversity of a population. As the effective size decreases, the effect of genetic drift will be stronger and the efficacy of selection lower. This concept can be applied at the population level, but also at the genome or gene levels. For example, Ne is affected by the mode of inheritance: due to uniparental inheritance, Ne is lower for organellar genes than for autosomal ones which are transmitted biparentally [106].
Functional gene transfer	transfer of an organellar gene and its function to the nucleus. The new nuclear gene will be targeted back to the organelle and the redundant organellar gene will be eventually lost [94].
Genetic drift	Evolutionary process represented by the random sampling of alleles. It leads to changes in allele frequencies in a population over generation and influence population genetic diversity and divergence among populations.
Heteroplasmy	co-occurrence of two or more different organelle genotypes within an individual, which can be the result of biparental transmission.
Intergenomic coevolution	involves reciprocal effects of selection on interacting molecules from two genomes [16].
Non-Synonymous substitutions (NS)	single-nucleotide mutations leading to changes of amino-acid in the encoded polypeptide.
Paternal leakage	occasional transmission of paternal organellar genome.
Synonymous substitutions (S)	single-nucleotide mutations that do not result into changes of amino-acid in the encoded polypeptide.
Variegation	presence of different colors, from green to white, on sectors on the same leaves or on different leaves of the same plant.