Breeding of Fruit and Plantation Crops 2 + 1

Genetic variation within clones

 
• Genetic variation within clones may be due to mutation, mechanical mixture and sexual reproduction.
a.Mutation

• Somatic mutations are also known as bud mutations. The frequency of mutations is generally very low. A mutant allele would be homozygous only when
1. Both the alleles in the cell mutate at the same time producing the same mutant allele, or
2. The mutant allele is already in the heterozygous condition in the original clone. Dominant bud mutations express themselves more frequently than the recessive ones, as recessive mutation get expressed only under homozygous conditions. Bud mutations often produce chimeras, i.e., individuals containing cells of two or more genotypes. However, it is not a great problem because normal plants, i.e., non chimeras, may be produced from chimeras by several techniques.
b. Mechanical mixture

• Mechanical mixture produces genetic variation within a clone, similar to the manner as seen in pure lines.
c. Sexual reproduction

• Occasional sexual reproduction leads to segregation and recombination. The seedlings obtained from sexual reproduction are genotypically different from the asexual progeny.