Tomato cybrids with mitochondrial DNA from Lycopersicon pennelli

Abstract

Cybrids have been regenerated following protoplast fusion of iodoacetamide-treated leaf mesophyll cells of Lycopersion esculentum cv UC82 and gamma-irradiated cell suspensions of L. pennellii, LA716. The cybrids were recovered in the regenerant population at a frequency of 19%, no selection pressure was applied for the persistence of the donor cytoplasm. The nuclear genotype of ten cybrids was characterized extensively using isozyme markers, cDNA-based restriction fragment length polymorphisms (RFLPs), and the morphology of the plants. No nuclear genetic information from L. pennellii was detected in the cybrids. The organellar genotype of the cybrids was determined using cloned probes and species-specific RFLPs. All the cybrids had inherited the tomato chloroplast genome and had varying amounts of L. pennellii mitochondrial DNA. The cybrids all had a diploid chromosome number of 24, produced pollen, and set seed.

Molecular and Ultrastructural Analysis of a Nonchromosomal Variegated Mutant (Tomato Mitochondrial Mutants That Cause Abnormal Leaf Development)

“…cv UC82 and Lycopersicon pennellii, Corr., LA716 (Bonnema, 1990;Bonnema et al, 1991Bonnema et al, , 1992. The cybrids were classified into one of two groups: group I contained plants with small, deformed, variegated leaves and greater than 50% L. pennellii mtDNA (plant Nos.…”

“…The methods described by Bonnema et al (1991) were used for Southern hybridization. Oligonucleotidelabeled probes were prepared from gel-purified inserts of recombinant clones carrying the mitochondrial genes:…”

“…To identify a species-specific RFLP in ctDNA, oligonucleotide-labeled probes were prepared from gel-purified inserts of a recombinant clone carrying a 27-kb Sal1 fragment from tomato ctDNA (Bonnema et al, 1991).…”

“…The chloroplast genotype of the regenerants had previously been determined using a species-specific Hmdlll polymorphism (Bonnema et al, 1991). All of the cybrids displayed the tomato-specific RFLP.…”

“…In one case, CMS tomatoes have been produced following the regeneration of tomato cybrids with portions of the mitochondrial genome of Solanum acaule (Melchers et al, 1992). We have constructed tomato cybrids that have tomato nuclear and chloroplast genomes but mitochondrial genomes that are recombinant between tomato (Lycopersicon esculentum) and L. pennellii (Bonnema et al, 1991). Severa1 individuals in this cybrid population have an abnormal leaf development and reduced vigor.…”