DONOR CHROMOSOME ELIMINATION AND ORGANELLE COMPOSITION OF ASYMMETRIC SOMATIC HYBRID PLANTS BETWEEN AN INTERSPECIFIC TOMATO HYBRID AND EGGPLANT

Morphology, the extent of elimination of donor chromosomes and the org anelle composition of highly asymmetric somatic hybrid plants between a interspecific tomato hybrid Lycopersicon esculentum x L. pennellii ( EP) as donor and a Solanum melongena, eggplant (E), recipient, were st udied. Morphologically, the somatic hybrids most resemble eggplant but , due to polyploidy, growth is slower relative to both fusion parents. The somatic hybrids produce flowers that are characterized by abnorma l styles, stigmas and by anthers which do not produce pollen. Limited amounts of donor EP genomic DNA were found in the three somatic hybrid plants (H18-1, H18-2 and H18-3), by dot-blot hybridization with probe pTHG2, equivalent to 6.23, 5.41, and 5.95% EP, respectiveIy. These pe rcentages translated to the presence of 3.59, 2.90 and 3.19 average, s ize EP chromosomes in planes H18-1, -2 and -3, respectively, RFLP dete rmination of L. esculentum and L. pennellii-specific chromosomes revea led that only fragments of eight to ten out of the 24 EP chromosomes ( EP has 12 L. esculentum and 12 L. pennellii chromosomes) are present i n the asymmetric somatic hybrid plants. Loci of L. esculentum and L. p ennellii were evenly represented in plants H18-1, -2, and -3: four to five from L. esculentum and four to five from L. pennellii. All somati c hybrid plants retained locus TG22, chromosome 4, from both EP specie s. Although the regenertion of plants, H18-1, -2 and -3 was from one c allus, loci TG31 and TG79 of L. esculentum chromosome 2 and L. pennell ii chromosome 9, respectively, were missing in hybrid plant H18-1. The three somatic hybrid plants all had chloroplast DNA fragments specifi c for S. melongena. The mitochondrial genome (mtDNA) in the asymmetric somatic hybrids showed predominantly the pattern of eggplant; however , some eggplant-specific polymorphic bands were not present in the thr ee plants.