Multiple and asymmetrical origin of polyploid dog rose hybrids (RosaL. sect.Caninae(DC.) Ser.) involving unreduced gametes

Abstract

The biased crossing barriers between subsections are explained by the facilitated production of unreduced gametes in subsect. Rubigineae . Unreduced egg cells probably provide the highly homologous chromosome sets required for correct chromosome pairing in hybrids. Furthermore, the higher frequency of Rubigineae hybrids is probably influenced by abundance effects because the plants of subsect. Caninae are much more abundant and thus provide large quantities of pollen. Hybrids are formed spontaneously, leading to highly diverse mixed stands, which are insufficiently characterized by the actual taxonomy.

The fate of ribosomal RNA genes in spontaneous polyploid dogrose hybrids [Rosa L. sect. Caninae (DC.) Ser.] exhibiting non‐symmetrical meiosis

“…Expression studies on ribotypes were contradictory: ribotypes were additively transcribed in flower buds of Rosa canina L. (Ritz et al ., ), but leaves showed stable expression of the Canina type and frequent silencing of others (Khaitová et al ., , ). These studies focussed either on established dogroses species or on synthetic hybrids; however, also ongoing spontaneous hybridization is frequent and contributes substantially to the diversity of extant dogroses (Schanzer and Vagina, ; Schanzer and Kutlunina, ; Ritz and Wissemann, ; Herklotz and Ritz, , ). Expression patterns of anonymous markers (cDNA‐AFLPs and MSAPs) in such a hybrid population were mostly additive, but also tissue‐specific effects were observed (Vogt et al ., ).…”

A high-quality sequence ofRosa chinensisto elucidate genome structure and ornamental traits

“…Hence, it is a unique model for polyploidisation and Chromosome pairing mechanisms. Pentaploid dogroses have a unique meiosis [49].…”

Genetic mapping in polyploids

“…Cultivated roses have an unusual recent pedigree (which ornamental species in particular, but also many other domesticated crop species have experienced), but the same may be true for e.g. naturally occurring polyploid roses (including the unbalanced meiosis in pentaploid dogroses (Herklotz and Ritz, 2016)). The genus Rosa is more than 30 million years old, but hybridsation between species has been extensive (Koopman et al, 2008;Fougère-Danezan et al, 2015), which may have led to widespread mixing of germplasm within hybrid rose varieties.…”