Abstract
The genetics underlying Cyto-Nuclear Incompatibility (CNI) was studied in Pelargonium interspecific hybrids. We created hybrids of 12 closely related crop wild relatives (CWR) with the ornamental P. × hortorum. Ten of the resulting 12 (F1) interspecific hybrids segregate for chlorosis suggesting biparental plastid inheritance. The segregation ratios of the interspecific F2 populations show nuclear interactions of one, two, or three nuclear genes regulating plastid function dependent on the parents. We further validated that biparental inheritance of plastids is common in section Ciconium, using diagnostic PCR primers. Our results pave the way for using the diverse species from section Ciconium, each with its own set of characteristics, as novel sources of desired breeding traits for P. × hortorum cultivars.
Highlights
Several closely related species from Pelargonium sect
When genotyping the F1 plants, we found that green individuals contained the P. zonale type plastid (ZONA), whereas chlorotic individuals contained that of P. frutetorum/P. inquinans (FRIN) (Tables 2, 3 plastids of “maternal origin”)
We have found maternal (P. frutetorum/inquinans; FRIN) and paternal inheritance in most our offspring indicating that the ability to inherit and express more than one plastid is the rule rather than the exception in Pelargonium section Ciconium
Summary
Several closely related species from Pelargonium sect. Ciconium have been used for producing hybrids that are sold world-wide, commonly known as “garden geraniums,” that are some of the most popular and iconic ornamentals. There are genetic barriers to establishing crosses and making new hybrids, including Cyto-Nuclear Incompatibility (CNI) that can cause cytoplasmic male sterility (CMS), dwarf growth (DG) and chlorosis in hybrid offspring (Greiner et al, 2015; Postel and Touzet, 2020). Most angiosperms have uniparental maternal organelle inheritance. Pelargonium × hortorum as well as the species P. zonale display biparental inheritance of their organelles (Baur, 1909; Tilney-Bassett et al, 1992; Weihe et al, 2009). Inheritance of organelles in plants with biparental transmission was found to be non-Mendelian
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