The number of chromosomes a rose has is not a single fixed number but varies depending on the specific type of rose. Based on scientific study of the genus Rosa, the chromosome number ranges significantly.
A rose can have between 14 and 56 chromosomes.
Chromosome Numbers in Roses
The variation in chromosome count among different rose species and cultivars is primarily due to a phenomenon called polyploidy. This means that while some roses are diploid (having two sets of chromosomes), others have multiple sets (polyploid), such as triploid (three sets), tetraploid (four sets), hexaploid (six sets), or even octoploid (eight sets).
According to research:
Chromosome numbers in the genus Rosa range from 2n = 2x = 14 to 2n = 8 x = 56 and aneuploidy is rare.
Let's break down what this means:
- 2n: Represents the total number of chromosomes in a somatic (non-reproductive) cell of the plant.
- x: Represents the basic set of chromosomes, which is 7 in roses.
- 2x: Means two sets of chromosomes (diploid), so 2 * 7 = 14 chromosomes (2n=14).
- 8x: Means eight sets of chromosomes (octoploid), so 8 * 7 = 56 chromosomes (2n=56).
This indicates that rose plants can naturally exist with varying numbers of chromosome sets, leading to the wide range of chromosome counts observed. The reference also notes that aneuploidy (having an abnormal number of chromosomes that isn't an exact multiple of the basic set) is rare in roses.
Range of Chromosome Counts in the Genus Rosa
The table below illustrates how different ploidy levels correspond to the chromosome numbers found in roses, based on the basic set of x=7 chromosomes:
| Ploidy Level | Number of Chromosome Sets (x) | Total Chromosomes (2n) |
|---|---|---|
| Diploid | 2x | 14 |
| Triploid | 3x | 21 |
| Tetraploid | 4x | 28 |
| Pentaploid | 5x | 35 |
| Hexaploid | 6x | 42 |
| Heptaploid | 7x | 49 |
| Octoploid | 8x | 56 |
This variation in chromosome number contributes to the incredible diversity seen in the world of roses, from species in the wild to the countless cultivated varieties.
