Dihaploids

A dihaploid is an organism or cell that contains two complete sets of chromosomes, but with one set originating from each parent in a sexually reproducing species, it is the normal diploid state. In contrast, a dihaploid refers to a set of chromosomes that is derived from a single gamete. This means a dihaploid contains half the number of chromosomes of a normal diploid organism, but these chromosomes are not homologous pairs; instead, they are duplicated sets of chromosomes that have originated from a single gamete. This state is often achieved through artificial means in plant breeding and research.

The process of creating dihaploids typically involves techniques like anther culture or ovule culture. In anther culture, immature pollen grains are cultured in vitro. These pollen grains, which are haploid (containing only one set of chromosomes), can be induced to develop into embryos or callus tissue. This tissue can then be regenerated into a whole plant. If the chromosome number of the pollen grains doubles spontaneously during this process, or if a chemical treatment is applied to induce chromosome doubling, a fully dihaploid plant is produced. These plants have two identical sets of chromosomes, each set being a duplicate of the original haploid genome.

Dihaploid plants are highly valuable in plant breeding and genetics. Because they are homozygous for all genes, they are genetically uniform, meaning all offspring will be identical. This eliminates the need for multiple generations of inbreeding to achieve homozygosity, significantly accelerating the breeding process. Dihaploid technology allows breeders to quickly develop new varieties with desirable traits, such as disease resistance or improved yield. Furthermore, dihaploids are crucial for genetic mapping and the study of gene function, as their homozygous nature simplifies genetic analyses.