Cybrid production and selection

Overview

The term cybrid cell will be used below in the sense of a cell harboring a nuclear genome of a given species (the recipient) but containing an alien chloroplast genome (plastome) and/or a mitochondrial genome (chondriome) that is partially or totally alien (from the donor fusion-partner). A cybrid plant will mean a plant composed of cybrid cells; we shall use the term cybridization for the act of producing cybrid cells or cybrid plants. In angiosperm plants chloroplasts probably maintain their organelle-integrity; consequently when chloroplasts containing different plastomes reside in the same cell, they will very rarely exchange chloroplast DNA (ctDNA). On the other hand when mitochondria containing different chondriomes will be harbored in the very same cell they probably fuse and defuse allowing exchanges of their respective mitochondrial DNA (mtDNA). Therefore cybridization will usually have different consequences for the plastome and the chondriome compositions of the derived cybrid plants. Namely, the cybrids will contain only the donor’s plastome, will be heteroplastomic (with the endogenous plastome as well as an alien plastome) or will retain only the recipient’s plastome. Not so in respect to chondriome composition: the cybrid may contain only the donor’s chondriome or only the recipient’s chondriome but more commonly the cybrid will contain a novel chondriome derived from mtDNA exchanges between the donor’s and the recipient’s chondriome [1].