OUR SERVICES
We offer two different ways of analysing the DNA content of nuclei. One is DAPI based, which only stains the nucleotides Adenine and Thymine (AT). The other is PI based, which stains all four nucleotides (ATGC). The combination of the 2 different analysis, gives information about the %GC.
Simple ploidy analysis
This type of analysis is DAPI based. The samples are compared with a sample of known ploidy of the same species, delivered by the customer.
If a sample of known ploidy is not available than the results will tell you whether or not there is ploidy variation.
When a sample of known ploidy is not available than it is an option to use the service genome size and compare the results of your samples with what is published.
The most common applications are:
- Describing plants derived from chemical polyploidisation experiments
- Identifying triploids
- Testing ploidy uniformity
- Identifying haploids from microspore/anther culture
- Describing ploidy variations in plants from natural stands
Relative DNA content
This type of analysis is based on DAPI. The plants are measured together with an internal standard. The results are presented as ratio of the sample to the standard.
In many genera species vary in genome size. This variation can also be measured with this type of analysis. However, this works only when the %GC is equal for all species (see Determining %GC). If plants differ in % GC than DAPI ratios will overestimate actual differences in genome size.
The most common applications are:
- Describing complex ploidy variation
- Identifying interspecific or intergeneric hybrids
- Describing variation in species from a genus
- Describing variation in natural stands
Genome size
This service is PI based. The samples are measured together with an internal standard. In this service another stain is used which allows the measurement of all nucleotides. The results are presented as ratio to the internal standard (so called absolute DNA ratio). The genome size of the internal standard is known and from this the genome size of the samples are calculated. The results are presented as pg/2C or MBP/2C.
The most common applications are:
- Describing variation in species from a genus
- Describing variation in natural stands
- Comparing genome size with published data to estimate ploidy level
- Obtaining estimate for %GC (this is done by evaluating DAPI ratio/PI ratio.
Analysing male/female gametes
The ploidy of male gametes can be measured for a high number of species. Male gamete formation is a very complex process. During normal development a 2x plant will have male gametes with a ploidy of x, 2x and 4x. Normally a 2x plant will produce x male gametes. Many species also produce so called 2n gametes who are 2x. Mostly the frequency of 2n gametes is low to very low.
In general, 2n male gametes formation is higher in interspecific or -generic plants and in polyploidised plants. In some cases it can be the dominant type.
The ploidy of female gametes cannot be measured directly. It can only be measured by analysing developing/mature seeds.
The most common applications are:
- Detecting 3x plants when 2x or 4x control plants are not available.
- Describing male gametes in interspecific hybrids
- Describing male gamete formation in 3x plants
- Identify genotypes with 2n gametes (female or male).
- Predict outcome from microspore culture.
- Identify whether mixoploid plants, derived from chemical polyploidisation, produce polyploidised pollen.
Determining %GC
Two stains are currently used to measure DNA content. DAPI stains the nucleotides adenine and thymine. PI stains all 4 nucleotides. The DAPI/PI ratio of samples measured with a standard can be used to estimate the %GC [1].
The most common applications are:
- Determining variation in %GC in species of a genus
- Determining successful hybridisation