Spontaneous and induced loss of chromosomes in slow-growing somatic hybrid calli of Solanum tuberosum and Nicotiana plumbaginifolia

Abstract

Rate and extent of spontaneous and induced chromosome loss have been determined at the callus level of somatic hybrids of mutants of Solanum tuberosum and Nicotiana plumbaginifolia. AEC (amino ethyl cystein) resistance in potato and Nitrate-Reductase deficiency in N. plumbaginifolia have been used as genetic markers and chromosome morphology as a cytological marker. In this combination, development of hybrid callus was late and slow. Only a limited number of non-regenerable hybrid calli have become available. Chromosome loss could clearly be established in these hybrids from loss of markers and from chromosome cytology. Loss of markers occurred independantly.The best conditions to induce loss of chromosomal material in donor cells by irradiation were found by cytological investigations. A very drastic reduction in chromosome transfer by fusion could be effected by irradiation of plant tissue and subsequent preparation of protoplasts after a few days. Following fusion, hybrid callus was recovered with the potato genome drastically reduced. The amount of loss was deduced from the presence of a few fragments in metaphase cells or from interphase nuclei after in situ hybridization with a repetitive potato DNA probe.

Isolation of sub-diploid microprotoplasts for partial genome transfer in plants: Enhancement of micronucleation and enrichment of microprotoplasts with one or a few chromosomes

“…In this regard somatic hybridization is a promising approach for transfer and genetic analysis of the traits, thus facilitating the isolation of the genes involved. However, in this case, the fusion of donor protoplasts with whole genomes, or after irradiation, has so far resulted in genetically complex hybrids with several donor chromosomes and unwanted genes (Famelaer et al 1990;Piastuch and Bates 1990;Wijbrandi et al 1990;Tempelaar et al 1991 ;Wolters et al 1991;Gilissen et al 1992). Therefore, donor microprotoplasts containing one or a few chromosomes with the desired gene(s) (partial genome) are required for the production of asymmetric hybrids.…”

Intergeneric somatic hybridization and its application to crop genetic improvement

“…Nicotiana Wolters et al (1993a, b), Ramulu et al (1995) and Vlahova et al (1997) Solanum Handley et al (1986), O'Connell and Hanson (1986, Sakomoto and Taguchi (1991), Gavrilenko et al (1992), Guri et al (1988), Hossain et al (1994, Sherraf et al (1994), Schoenmakers et al (1993Schoenmakers et al ( , 1994a and Kobayashi et al (1996), Melchers et al (1992), McCabe et al (1993), and Medicago Lotus Kaimori et al (1998) Onobrychis Li et al (1993) Nicotiana Solanum Vries et al (1987, Wan et al (1988), Toki et al (1990) and Gilissen et al (1992) Perl et al (1991, Thanh and Medgyesy (1989), Ramulu et al (1995Ramulu et al ( , 1996a, Tempelaar et al (1991), Wolters et al (1991) and Schoenmakers et al (1994a,b …”

“…In most of the asymmetric fusions, protoplasts that have been purified or are being isolated were irradiated before fusion (Somers et al, 1986;Vlahova et al, 1997;Kaimori et al, 1998;Zubko et al, 2002). But callus, leaf, cell suspension cultures or in vitro plantlets have also been used for irradiation prior to protoplast isolation (Tempelaar et al, 1991;Wolters et al, 1991;Hansen and Earle, 1997). Response to the irradiation varied in different tissues.…”

“…The conflicting results may be attributed to the fact that irradiation-caused chromosome elimination is not exclusive but possibly affected by other elements like genotype, irradiation type, phylogenetic relationship between the fusion parents and physiological status of the irradiated materials . Additionally, dose-effect can be modified by the repairing facility present in the irradiated cells (Tempelaar et al, 1991).…”