© 2007 Heron Publishing—Victoria, Canada
Plant somatic hybrid cytoplasmic DNA characterization by single-strand conformation polymorphism
Óscar Olivares-Fuster (1), María Hernández-Garrido (1), José Guerri (1) and Luis Navarro (1,2)
1. Department of Plant Protection and Biotechnology, Instituto Valenciano de Investigaciones Agrarias (IVIA), Apartado Oficial
46113, Moncada, Valencia, Spain / 2. Corresponding author (lnavarro@ivia.es) / Received April 30, 2006; accepted June 4, 2006; published online March 1, 2007
Summary
Unlike maternal inheritance in sexual hybridization, plant somatic hybridization allows transfer, mixing and recombination
of cytoplasmic genomes. In addition to the use of somatic hybridization in plant breeding programs, application of this unique
tool should lead to a better understanding of the roles played by the chloroplastic and mitochondrial genomes in determining
agronomically important traits. The nucleotide sequences of cytoplasmic genomes are much more conserved than those of nuclear
genomes. Cytoplasmic DNA composition in somatic hybrids is commonly elucidated either by length polymorphism analysis of restricted
genome regions amplified with universal primers (PCR-RF) or by hybridization of total DNA using universal cytoplasmic probes.
In this study, we demonstrate that single-stranded conformational polymorphism (SSCP) analysis is a powerful, quick and easy
alternative method for cytoplasmic DNA characterization of somatic hybrids, especially for mitochondrial DNA. The technique
allows detection of polymorphisms based on both size and sequence of amplified targets. Twenty-two species of the subfamily
Aurantioideae were analyzed with eight universal primers (four from chloroplastic and four from mitochondrial regions). Differences
in chloroplastic DNA composition were scored in 98% of all possible two-parent combinations, and different mitochondrial DNA
profiles were found in 87% of them. Analysis by SSCP was also successfully used to characterize somatic hybrids and cybrids
obtained by fusion of Citrus sinensis (L.) Osb. and C. excelsa Wester protoplasts.
Keywords:
chloroplastic DNA, citrus, mitochondrial DNA, plant protoplast fusion.
