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This image shows haploid (single), diploid (double), triploid (triple), and tetraploid (quadruple) sets of chromosomes. Triploid and tetraploid chromosomes are examples of polyploidy. Polyploidy is a condition in which the cells of an organism have more than two paired sets of chromosomes.
An image of multiple chromosomes, taken from many cells. Plant genetics is the study of genes, genetic variation, and heredity specifically in plants. [1] [2] It is generally considered a field of biology and botany, but intersects frequently with many other life sciences and is strongly linked with the study of information systems.
Random mutations are the ultimate source of genetic variation. Mutations are likely to be rare, and most mutations are neutral or deleterious, but in some instances, the new alleles can be favored by natural selection. Polyploidy is an example of chromosomal mutation. Polyploidy is a condition wherein organisms have three or more sets of ...
Mutation breeding, sometimes referred to as "variation breeding", is the process of exposing seeds to chemicals, radiation, or enzymes [1] [2] in order to generate mutants with desirable traits to be bred with other cultivars. Plants created using mutagenesis are sometimes called mutagenic plants or mutagenic seeds.
Somaclonal variation is the variation seen in plants that have been produced by plant tissue culture. Chromosomal rearrangements are an important source of this variation. . The term somaclonal variation is a phenomenon of broad taxonomic occurrence, reported for species of different ploidy levels, and for outcrossing and inbreeding, vegetatively and seed propagated, and cultivated and non ...
Polysomy of chromosomes 1, 2, 4, 5, and 25 are also frequently involved in canine tumors. [16] Chromosome 1 may contain a gene responsible for tumor development and lead to changes in the karyotype, including fusion of the centromere, or centric fusions. [16] Aneuploidy due to nondisjunction is a common feature in tumor cells. [17]
Mutations may also result from substitution, insertion or deletion of segments of DNA due to mobile genetic elements. [5] [6] [7] A red tulip exhibiting a partially yellow petal due to a somatic mutation in a cell that formed that petal. Mutations may or may not produce detectable changes in the observable characteristics of an organism.
As these chromosomes diverge from their autosomal ancestor and from each other as a homologous pair, they have the potential to increase or decrease in size due to mutation and recombination. In the case of Silene , the pair of automsomal chromosomes are transformed into heteromorphic sex-determining chromosomes expressed as XY.