DIPLOTAXIS CATHOLICA PLUS BRASSICA-JUNCEA SOMATIC HYBRIDS - MOLECULARAND CYTOGENETIC CHARACTERIZATION

Intergeneric somatic hybrids Diplotaxis catholica (2n=18) + Brassica j uncea (2n=36) were produced by fusing mesophyll protoplasts of the for mer and hypocotyl protoplasts of the latter using polyethylene glycol, Out of 52 somatic embryos, 24 produced intermediate morphology. Cytol ogical 16 plants indicated that 15 were symmetric hybrids carrying 54 chromosomes, the sum of the parental chromosome numbers. One hybrid wa s asymmetric with 45 chromosomes. Nuclear hybridity of five putative h ybrids was confirmed by the Southern hybridization pattern of full len gth 18s-25s wheat nuclear rDNA probe which revealed the presence of Hi nd III fragments characteristic of both the parental species. The hybr idization pattern of mitochondria specific gene probe cox I indicated that three of the hybrids carried B.juncea mitochondria and one carrie d mitochondria of D. catholica. Presence of novel 3.5 kb Hind III and 4.8 kb Bgl II fragments suggested the occurrence of mtDNA recombinatio n in one of the hybrids. The hybrids were pollen sterile. However, see ds were obtained from most of the hybrids by back crossing with B. jun cea.