Karyotypic variation and pollen stainability in resynthesized allopolyploids Tragopogon miscellus and T. mirus

December 31st, 2017
By Gitzendanner, Matt

Spoelhof, J. P., M. Chester, R. Rodriguez, B. Geraci, K. Heo, E. Mavrodiev, P. S. Soltis, and D. E. Soltis. 2017. Karyotypic variation and pollen stainability in resynthesized allopolyploids Tragopogon miscellus and T. mirus. American Journal of Botany 104:1484–1492. [View on publisher’s site]

Abstract

PREMISE OF THE STUDY:

Polyploidy has extensively shaped the evolution of plants, but the early stages of polyploidy are still poorly understood. The neoallopolyploid species Tragopogon mirus and Tmiscellusare both characterized by widespread karyotypic variation, including frequent aneuploidy and intergenomic translocations. Our study illuminates the origins and early impacts of this variation by addressing two questions: How quickly does karyotypic variation accumulate in Tragopogon allopolyploids following whole-genome duplication (WGD), and how does the fertility of resynthesized Tragopogon allopolyploids evolve shortly after WGD?

METHODS:

We used genomic in situ hybridization and lactophenol-cotton blue staining to estimate the karyotypic variation and pollen stainability, respectively, of resynthesized Tmirus and Tmiscellus during the first five generations after WGD.

KEY RESULTS:

Widespread karyotypic variation developed quickly in synthetics and resembled that of naturally occurring Tmirus and Tmiscellus by generation S4. Pollen stainability in resynthesized allopolyploids was consistently lower than that of natural Tmirus and Tmiscellus, as well as their respective diploid progenitor species. Logistic regression showed that mean pollen stainability increased slightly over four generations in resynthesized Tmirus but remained at equivalent levels in Tmiscellus.

CONCLUSIONS:

Our results clarify some of the changes that occur in Tmirus and Tmiscellus immediately following their origin, most notably the rapid onset of karyotypic variation within these species immediately following WGD.

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