Principles of Plant Breeding (2+1)

Induction of aneuploids

1. The most commonly studied aneuploids in genetics and breeding are monosomics, nullisomics and trisomics.
2. These may originate spontaneously through meiotic irregularity but their frequency is very low .The aneuploids arise by fusion of unbalanced gametes, which result from meiotic irregularities.
 
3. Autopolyploids are characterized by increased cell size and vigorous plant growth and size of reproductive organs especially sepals, petals and fruit with few seeds in most of the cases.
   
4. The irregular meiosis due to multivalent formation causes high degree of pollen inviability and reduced fertility.
5. Aneuploids in general are weaker than diploids and nullisomics or even monosomics may not even survive especially in many diploid species.
 
6. The aneuploids show wide range of segregation distortions and variable degree of viability.
   
7. A very low rate of direct use in plant breeding.