The chromosome substitution procedure permits the introduction of a chromosome carrying a desirable gene without acquiring genes with adverse or deleterious effects from other chromosomes of the donor cultivar or species which would occur with conventional crossing and segregation. The use of monosomics is becoming obsolete with the advent of molecular techniques to map genomes and genetic engineering techniques for gene transfer. Hexaploid species have a greater genetic redundancy then tetraploids so they can compensate for the loss of a chromosome pair better. Nullisomics can also be used to identify or assign genes to specific chromosomes. Because of a loss in vigor, nullisomic analyses is less practical than monosomic techniques.
Spontaneous haploids occur at a low frequency in many species, both diploid and polyploid.
Often naturally occurring haploids can be recognized because they are smaller. Haploid plants can be treated with colchicine to produce diploid sectors or plants and are called doubled haploids. Haploid plants are useful in mutation studies. Selection for dominant alleles is easier in haploids. Since haploid, only 1 allele per locus so if dominant, then doubled, the doubled plant has 2 copies of the dominant allele.