Interspecific transfer of cytoplasmic male sterility by fusion between protoplasts of normal Nicotiana sylvestris and X-ray irradiated protoplasts of male-sterile N. tabacum

Zelcer, A.; Aviv, D.; Galun, E.

Zeitschrift fur Pflanzenphysiologie 90(5): 397-407


DOI: 10.1016/s0044-328x(78)80207-4
Accession: 000685467

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X-irradiated protoplasts of plants of cytoplasmically male-sterile (CMS) line 92, derived from N. suaveolens and N. tabacum by backcrossing and containing N. suaveolens cytoplasm and N. tabacum nuclei, were fused with protoplasts of N. sylvestris. The selection of fusion products was obtained by suppression of cell division by X irradiation of the CMS-line protoplasts and by the use of mannitol, which is unfavourable to protoplasts of N. sylvestris; the protoplast "feeder-layer" technique facilitated the isolation of fusion products which withstood the selection procedure. Thirty-one mature plants, regenerated from seven calluses, were obtained. Of these, 21 plants (Type A) had the shoot, leaf and perianth of N. sylvestris but their anthers resembled those of CMS N. tabacum and were male-sterile. Of these 21, seven plants had 2n = 24 chromosomes and 14 plants had 2n = 48 chromosomes. Six plants (Type B) grew as rosettes and bore flowers which were similar to those of N. sylvestris, but had deformed leaves and during further growth were similar to N. tabacum; their anthers were sterile but normal, or almost normal, in structure. Of these six, four plants had 2n = 48 chromosomes and two plants had 2n = 76-80 chromosomes. Five plants (Type C), all resulting from one callus, were identical in shoot, leaf and floral morphology with CMS N. tabacum. These plants are considered to have developed from a CMS N. tabacum protoplast which escaped X irradiation. It is concluded that Type A plants bore the genome of N. sylvestris while their plastome was partially or entirely derived from N. suaveolens. Type A plants, which formed the majority of the fusion products, are considered to be somatic hybrids resulting from the transfer of cytoplasmic-male sterility into N. sylvestris cells. Type B plants probably had a mainly N. sylvestris genome but also had some N. tabacum genes; their cytoplasm was probably not entirely from N. sylvestris. The fusion procedure is considered to have general applicability to the transfer of cytoplasmic-male sterility, as well as other cytoplasmic factors, which are difficult to transfer by conventional genetic techniques.