Dog roses

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Dog roses
Dog rose (Rosa canina)

Dog rose ( Rosa canina )

Systematics
Order : Rose-like (rosales)
Family : Rose family (Rosaceae)
Subfamily : Rosoideae
Genre : Roses ( pink )
Subgenus : pink
Section : Dog roses
Scientific name
Caninae
DC.

The dog roses ( Rosa sect. Caninae ) are a section from the genus of roses ( Rosa ). It includes around 60 species. It is a hybridogenic group, the species of which are often linked by hybrids and intermediate forms. It has a special form of meiosis , balanced heterogamy .

description

Dog rose illustration ( Rosa canina )

Vegetative characteristics

The dog roses are shrubs with or without runners . They usually have spines of the same type , only rarely and only in a few species are there dissimilar spines. They are hooked or sickle-shaped, they are rarely straight to slightly curved. The alternately arranged leaves are pinnate five to seven, rarely nine.

Generative characteristics

The hermaphroditic flowers are radial symmetry and five-fold with a double flower envelope . The outer sepals are mostly divided, in some species they are almost or completely undivided. After the anthesis the sepals are turned back, protruding or erect; they can fall off or stay, early or late. There are five free petals . There are many stamens present. The stylus canal is narrow to wide, the scar head is of the hat or bouquet type.

The number of chromosomes is 2n = 28, 35, 42.

Canina meiosis

In the species of the Caninae section , the meiosis is irregular. It is called balanced heterogamy or, because of its restriction to the dissection, also called canina meiosis.

The species of the section Caninae often have an odd number of chromosomes ( anorthoploidy ), many are pentaploid with 2n = 35 chromosomes. Normal meiosis is therefore not possible.

At the beginning of meiosis (in the syndesis) 14 of the 35 chromosomes mate to 7 pairs (bivalents), the remaining 21 remain unpaired (univalents). The distribution of the chromosomes is different in pollen and embryo sac mother cells :

  • Only two of the five sets of chromosomes mate in the pollen sac mother cells. The remaining chromosomes arrange themselves individually in the equatorial plane and migrate towards the pole with a delay. After meiosis, the formed pollen grains contain the seven chromosomes that are capable of pairing and next to them a random number of chromosomes that are incapable of pairing (univalents). All pollen grains that have such univalents wither. Only those pollen grains that contain only the bivalent (n = 7) are capable of fertilization.
  • In embryo sac mother cells , the process is reversed, a fertilizable egg cell also contains all univalents, the number of chromosomes is n = 28.

During fertilization , the fusion of the sperm cell (n = 7) and the egg cell (n = 28) results in the original set of chromosomes (2n = 35) being restored. Due to the different share of the parents in the genetic makeup (4/5 of the seed- parent ), hybrids from the autopsy are much more similar to the female parent (matroclinic). However, some morphological features, such as the durability of the sepals or the diameter of the stylus canal, are not inherited matroclinically, but from the pollen parent.

In the tetraploid and hexaploid species of the section, 7 or 14 bivalents and 7 or 14 univalents are formed accordingly. Here, too, the univalents are only transmitted through the egg cell.

Canina meiosis was first described by Täckholm, Blackburn and Harrison in 1920/1922

Systematics and distribution

The dog roses are a section within the subgenus Rosa of the genus Rosa . With around 60 species, it is the most species-rich section. For its part, it is divided into several subsections.

The types of the section were created by various hybridization events. They are of allopolyploid origin and contain genomes of various non- Caninae sections as well as a genome called Protocaninae . Species that only have this Protocaninae genome no longer exist today. The Protocaninae genome is likely to form the bivalents in meiosis. The system within the section is difficult due to its hybridogenic origin. There are fertile hybrids between the species. Molecular genetic studies have shown that the section is polyphyletic. The types of the section are divided into two large groups, which are morphologically characterized by the presence or absence of scent glands. These two groups are separated from one another by a clade containing Rosa gallica and some species from the Synstylae - Indicae group.

The dog rose species occur in Eurasia and North Africa .

The subsections and species occurring in Central Europe are, according to Henker:

supporting documents

  • Heinz Henker: Pink. In: Hans. J. Conert et al. (Ed.): Gustav Hegi. Illustrated flora of Central Europe. Volume IV, Part 2C. Spermatophyta: Angiospermae: Dicotyledones 2 (4). Rosaceae (rose family). 2nd edition, Parey, Berlin 2003, ISBN 3-8263-3065-X , p. 10; 18-20.
  • Christiane Ritz: Evolution von Hundsrosen (Rosa L. sect. Caninae (DC.) SER.) , Dissertation at the Friedrich Schiller University Jena, 2005, 186 pages. Full text PDF.
  • Volker Wissemann, Friederike Gallenmüller, Christiane M. Ritz, Tina Steinbrecher, Thomas Speck: Inheritance of growth form and mechanical characters in reciprocal polyploid hybrids of Rosa section Caninae - implications for the ecological niche differentiation and radiation process of hybrid offspring. In: Trees - Structure and Function , Volume 20, Issue 3, 2006, pp. 340–347. doi : 10.1007 / s00468-005-0046-y

Individual evidence

  1. ↑ a b Volker Wissemann, Christiane M. Ritz: Evolutionary patterns and processes in the genus Rosa (Rosaceae) and their implications for host-parasite co-evolution. In: Plant Systematics and Evolution , Volume 266, 2007, pp. 79-89. doi : 10.1007 / s00606-007-0542-1
  2. ↑ Volker Wissemann, Christiane M. Ritz: The genus Rosa (Rosoideae, Rosaceae) revisited: molecular analysis of nrITS and atp B- rbc L intergenic spacer (IGS) versus conventional taxonomy. In: Botanical Journal of the Linnean Society , Volume 147, 2005, pp. 275-290. doi : 10.1111 / j.1095-8339.2005.00368.x
  3. ↑ Heinz Henker: Rosa . In: Hans. J. Conert et al. (Ed.): Gustav Hegi. Illustrated flora of Central Europe. Volume IV, Part 2C. Spermatophyta: Angiospermae: Dicotyledones 2 (4). Rosaceae (rose family). 2nd edition, Parey, Berlin 2003, p. 10; 18-20. ISBN 3-8263-3065-X
  4. ↑ a b c A. Kurtto, 2006: Rosaceae (pro parte majore). In: Euro + Med Plantbase - the information resource for Euro-Mediterranean plant diversity. : Datasheet Rosa

further reading

  • Volker Wissemann, M. Riedel, M. Riederer: Matroclinal inheritance of cuticular waxes in reciprocal hybrids of Rosa sect. Caninae (Rosaceae). In: Plant Systematics and Evolution , Volume 263, Issue 3/4, 2007, pp. 181-190. JSTOR 23655799