Somatic hybrids between unilateral cross-incompatible Petunia species

Abstract

Somatic hybrid plants regenerated following the fusion of leaf mesophyll protoplasts of Petunia parodii with those isolated from a cell suspension of albino P. inflata. These two species exhibit a unilateral cross-incompatability with a pre-zygotic mode of reproductive isolation preventing hybridizations with P. inflata as the maternal parent. Selection of somatic hybrids relied on the fact that unfused or homokaryon protoplasts of P. parodii did not develop beyond the cell colony stage while those of the putative somatic hybrids and albino P. inflata parent produced callus. Green somatic hybrid calluses were readily identified against the white background of P. inflata following complementation to chlorophyll synthesis proficiency and continued growth in hybrid cells. Shoots, and ultimately flowering plants, were identified as somatic hybrids based on their floral morphology and colour, chromosome number and the fact that they segregated for parental characters. The frequency of somatic hybrid production was comparable to that previously established for two sexually compatible Petunia species.

Protoplast isolation and plant regeneration of different genotypes of Petunia and Calibrachoa

“…Shoot regeneration appears to be genotype-dependent e (Bhojwani and Radzan 1996). Differences between species have been reported by Power et al (1979) after transferring callus of P. parodii and P. inflata onto media containing 1.0 mg l -1 zeatin or 2.0 mg l -1 IAA and 1.0 mg l -1 BA, respectively. P. parodii callus stopped growing whereas that of P. inflata continued to grow and regenerated shoots.…”

The Genetics of Petunia

“…In the same way, somatic hybrids of P. parodii + P. inflata were obtained by Power et al (1979) by means of an albino mutation carried by P. inflata. These two hybrids can be sexually produced, and they are fully fertile.…”

Peptide mapping of the ribulose bisphosphate carboxylase small subunit from the somatic hybrid of tomato and potato

“…However, some fertile amphidiploid somatic hybrids have been produced by protoplast fusion of lines and species, which can be hybridized sexually at least unilaterally e.g. in Nicotiana (1, 12) and Petunia (19). Aneuploids are also found in these cases (10,13).…”