The Minority

If the majority of plants exhibit maternal cytoplasmic inheritance, the plant breeders wonder about the species in the minority.  They find that there are almost as many variations of cytoplasmic inheritance as there are species of plants!  For example, most conifer species get all their organelle DNA from the father (Mogensen 1996).  The chloroplasts and mitochondria of the pollen are not degraded and are brought into the egg intact, fully able to pass on the organelle DNA.  Other species, like alfalfa, get some of the organelle DNA from the mother and some from the father.  This is called bi-parental inheritance.  Interestingly enough, cultivars or varieties within the alfalfa species can further be divided into “weak” or “strong” for passing on the mother’s organelle DNA.  Yet another example is the Chinese dwarf banana, which allows bi-paternal inheritance of mitochondria DNA, but the chloroplast DNA is only passed on from the mother (Zhang and Liu 2003).