Somatic Hybrids for Cytoplasmic Male Sterility, Mesophyll Protoplasts, Lycopersicon Esculentum, Iodoacetamide, Mitochondiria, Heterologous or Alloplasmic

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Protoplast Culture Regeneration and Somatic Hybridization Protoplast Culture Regeneration and Somatic Hybridization - Introduction Isolation of Proplasts Mechanical Method Enzymatic Method Direct One Step Method Sequential Two Step Method Purification of Isolated Protoplasts Sedimentation and Washing Flotation Viability and Plating Density of Protoplasts Testing Protoplast Viability Minimum Plating Density MPD and Culturing Individual Protaplasts Protaplast Culture and Regeneration of Plants Isolation of Subprotoplasts Protoplast Fusion and Somatic Hybridization Techniques of Protoplast Fusion

Home >> Plant Biotechnology and Genomics >> Protoplast Culture Regeneration and Somatic Hybridization >> Somatic Hybrids for Cytoplasmic Male Sterility

Somatic hybrids for cytoplasmic male sterility

Methods were also developed to substitute the nucleus of one species into the cytoplasm of another species, whose mitochondria were inactivated. This type of substitution in some cases, led to generation of cytoplasmic male sterility.

For this purpose, in an experiment, the two types of protoplasts, used for the production of somatic hybrids, were treated differently, as follows:

(i) mesophyll protoplasts of tomato (Lycopersicon esculentum) were treated with iodoacetamide (IOA) to inactivate mitochondria and

(ii) mesophyll protoplast of Solnum acaule (or S. tuberosum = potato) were irradiated with g or x-rays to inactivate nuclei.

The protoplasts were mixed in 1:1 ratio and induced to fuse using Ca2+ and PEG, leading to the production of Heterologous or alloplasmic hybrids.

Among the fusion products, some hybrid tomato plants were indistinguishable from the original cultivars, with respect to morphology, physiology and chromosome number (2n = 24), but exhibited various degrees of male sterility.

In five tomato cultivars, male sterility induced in this manner was inherited maternally over several generations. Therefore, it was obviously cytoplasmic male sterility.

The mitochondrial DNA of these CMS hybrids did not resemble mtDNA of either parent, and was instead recombinant type, representing a hybrid mitochondrial genome.

Therefore, protoplast fusion can be effectively used for production of CMS lines and has the following advantages:

(i) only one step is required; (ii) the nuclear genotype of the cultivar remains unaffected,

(iii) there are prospects that 100% of the progenies of somatic hybrids will be CMS. The restorer lines for these CMS lines have also been shown to be available in tomato, so that hybrid seed can be produced without manual emasculation.

Generation of Cytoplasmic make sterility by fusion

1. IOA (damages mitochondria)	8. Nucleus
2. γ rays or x-rays (inactivate nuclel)	9. tomato nucleus
3. mitochondria	10. recombinant mitochondira
4. chloroplast (tomato protoplasts)	11. chloroplasts (mixture)
5.Ca⁺⁺+ PEG	12. fused protoplasts
6. Protoplast fusion	13. somatic hybrid plants (CMS)-resemble tomato
7. chloroplast (potato or s.acaule protoplasts)

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Induced Fusion NaNo₃-treatment Treatment with Calcium Ions ca⁺⁺ at High pH Polyethylene Glycol PEG Treatment Electrical Fusion Selection of Fused Protaplasts Chromosome Status of Somatic Hybrids Interspecific Hybrids Produced Through Protoplast Fusion Intergeneric Hybrids Produced Through Protaplast Fusion Use of Protoplast Fusion and Somatic Hybrids Somatic Hybrids for Gene Transfer Asymmetry in Somatic Hybrids for Gene Transfer Somatic Hybrids for Cytoplasmic Male Sterility Cytoplasmic Hybrids or Cybrids Genetic Modification Transformation of Protoplasts