The phenomenon where double haploid (DH) G0 plants exhibit phenotypic and genetic similarities, despite originating from microspores that are theoretically genetically different, can be attributed to several factors:

### 1. **Somaclonal Variation**

Somaclonal variation refers to genetic and phenotypic variations observed in plants that have been produced through tissue culture techniques. However, in some cases, the tissue culture environment can induce genetic stability rather than variation, leading to phenotypic and genetic similarities among DH plants.

### 2. **Selection Pressure**

During the process of microspore culture and plant regeneration, selection pressures may favor certain genotypes over others. This can result in a population of DH plants that are more similar to each other than expected. Factors contributing to this include:

- **Culture Conditions**: Specific conditions of the culture medium (e.g., nutrient composition, hormones) can favor the development of certain microspores.

- **Regeneration Efficiency**: Some genotypes might have a higher efficiency of regeneration under the given culture conditions, leading to a biased representation in the DH population.

### 3. **Genetic Bottleneck**

The initial population of microspores may not fully represent the genetic diversity of the parent plant. If a relatively small number of microspores successfully develop into DH plants, this can lead to a genetic bottleneck, where the resulting plants are more genetically similar than the original microspore population.

### 4. **Epigenetic Factors**

Epigenetic modifications can play a significant role in the development and differentiation of microspores. These modifications can be inherited through mitotic divisions and might contribute to the observed phenotypic and genetic similarities among DH plants.

### 5. **Polygenic Traits**

Many phenotypic traits are controlled by multiple genes (polygenic traits). Even with genetic variation among microspores, the expression of these traits might converge due to polygenic inheritance patterns, resulting in phenotypically similar plants.

### 6. **Regeneration Protocol Standardization**

The standardization of protocols for microspore culture and plant regeneration can inadvertently select for microspores that respond uniformly to the in vitro conditions. This can reduce the observed genetic and phenotypic diversity among the resulting DH plants.

### 7. **Chromosomal Reorganization**

During the formation of DH plants, chromosomal reorganization can occur. If certain chromosomal configurations are more viable or stable, this can lead to a population of DH plants that share similar chromosomal structures, contributing to their genetic and phenotypic uniformity.

### 8. **Genetic Drift**

In small populations, genetic drift can lead to the random fixation of alleles. In the context of DH plant production, this can result in a population that is more genetically similar than expected due to the random loss of genetic variants during the culture process.

### References:

- Ahloowalia, B. S., & Maluszynski, M. (2001). "Induced mutations—a new paradigm in plant breeding." Euphytica, 118(2), 167-173.

- Larkin, P. J., & Scowcroft, W. R. (1981). "Somaclonal variation—a novel source of variability from cell cultures for plant improvement." Theoretical and Applied Genetics, 60(4), 197-214.

- Forster, B. P., & Thomas, W. T. B. (2005). "Doubled haploids in genetics and plant breeding." Plant Breeding Reviews, 25, 57-88.

By considering these factors, you can better understand why DH G0 plants might exhibit unexpected phenotypic and genetic similarities despite the theoretical genetic diversity of the original microspores.

Thank you so much Raghad Mouhamad sirji for your valuable response.

DH plants from anther culture methods are genetically similar because they are derived from a single haploid cell of one parent, and then diplotized. This process avoids the genetic recombination thus, giving no variation that would typically occur in sexual reproduction. Even if the starting material (the plant from which the microspores are derived) is heterozygous for certain traits, the DH plants produced from these anthers will still be homozygous at the genetic loci that were heterozygous in the original plant. If you are expecting some recessive traits to show up, better the test for the marker for it?

Dear Poonam ji,

a single haploid cell of one parent is different in genetic background because of meiotic recombination in the microspore development process...

Doubled haploid (DH) plants are produced from anther/microspores .. theoretically, each microspore can have a unique genetic composition due to meiotic recombination. so DH G0 plants will and /or must

appear phenotypically and genetically different ..na..

Thank you for your answer.

Double haploid G0 plants from anther culture are genetically identical because they originate from a single pollen grain. This means they lack genetic variation caused by the combination of two different parent's genes.

@ Chuck ji ,

one pollen one plantlet/embryoid ... so each pollen is different so plants generated will be different

Chuck A Arize

In an anther, microspores are produced through the process of meiosis in the pollen mother cells (also known as microsporocytes). Meiosis is a type of cell division that reduces the chromosome number by half, resulting in haploid cells. Here's a breakdown of the genetics of microspores in an anther:

Therefore, in a single anther, the microspores are genetically diverse, each representing different combinations of the parental genes. When these microspores are cultured to produce double haploid plants, each resulting plant will have a different genetic makeup unless they originated from the same Microspore.

DH development - there reports evidence for preferential development of some gametes into plants obtained. ex AB is doner , gametes A and B , preferential develop more plants from A gametes , so the DH developed from this gametes will be of same type ..