Spontaneous hybridization in wild roses

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A propensity to form polyploid hybrids is a peculiar feature of roses. Herklotz and Ritz investigate the population genetics of forty five mixed stands of dog roses across Central and South-Eastern Europe using microsatellite markers and flow cytometry.

Distribution of cytotypes and hybrids of subsect. Caninae and Rubigineae in the study area.
Distribution of cytotypes and hybrids of subsect. Caninae and Rubigineae in the study area. Study sites are abbreviated according to Table S1. The first bar plot represents the cytotypes in subsect. Caninae, the second bar plot cytotypes in the R. elliptica agg. and the third bar plot cytotypes in the R. rubiginosa agg. of subsect. Rubigineae. Localities with fewer than five samples are not shown (As, SE, HP, OB, UV; see Table S2). A, Austria; CZ, Czech Republic; D, Germany; HR, Croatia; H, Hungary; I, Italy; PL, Poland; SK, Slovakia; SLO, Slovenia; SRB, Serbia; UA, Ukraine.

They find that hybrids have originated independently at each locality with crossing barriers strongly biased towards the more abundant paternal parent. The majority of hybrids had a higher ploidy level than their parents because they emerged from unreduced egg cells. The authors conclude that the facilitation of unreduced egg cell formation in the maternal parent ensures correct chromosome pairing in hybrids.

Polyploidy Special Issue Cover This paper is part of the Annals of Botany Special Issue on Polyploidy in Ecology and Evolution. It will be free access until October 2017, then available only to subscribers until August 2018 when it will be free access again.

Reference

Herklotz, V., & Ritz, C. M. (2016). Multiple and asymmetrical origin of polyploid dog rose hybrids (Rosa L. sect. Caninae (DC.) Ser.) involving unreduced gametes. Annals of Botany, mcw217. https://doi.org/10.1093/aob/mcw217


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