Abstract

The Brassicaceae (Cruciferae) family, owing to its remarkable species, genetic, and physiological diversity as well as its significant economic potential, has become a model for polyploidy and evolutionary studies. Utilizing extensive transcriptome pyrosequencing of diverse taxa, we established a resolved phylogeny of a subset of crucifer species. We elucidated the frequency, age, and phylogenetic position of polyploidy and lineage separation events that have marked the evolutionary history of the Brassicaceae. Besides the well-known ancient α (47 million years ago [Mya]) and β (124 Mya) paleopolyploidy events, several species were shown to have undergone a further more recent (∼7 to 12 Mya) round of genome multiplication. We identified eight whole-genome duplications corresponding to at least five independent neo/mesopolyploidy events. Although the Brassicaceae family evolved from other eudicots at the beginning of the Cenozoic era of the Earth (60 Mya), major diversification occurred only during the Neogene period (0 to 23 Mya). Remarkably, the widespread species divergence, major polyploidy, and lineage separation events during Brassicaceae evolution are clustered in time around epoch transitions characterized by prolonged unstable climatic conditions. The synchronized diversification of Brassicaceae species suggests that polyploid events may have conferred higher adaptability and increased tolerance toward the drastically changing global environment, thus facilitating species radiation.

Highlights

  • Brassicaceae is one of the most diverse plant families, comprising 49 tribes, 321 genera, and over 3660 species (Al-Shehbaz, 2012), including economically important edible and industrial oilseed and vegetable crops as well as highly diverse wild germplasm (Warwick, 2011)

  • Polyploidy is recognized as an important mechanism of plant diversification as it can lead to the creation of new species and have profound effects on subsequent lineage evolution proportional to data fraction (Supplemental Data Set 1)

  • A table representing cluster average, SD, and estimated age of associated polyploidy events is appended below the scatterplot. (B) Age distributions of A. thaliana paralogs representing a, b, and g paleopolyploidy events

Read more

Summary

Introduction

Brassicaceae is one of the most diverse plant families, comprising 49 tribes, 321 genera, and over 3660 species (Al-Shehbaz, 2012), including economically important edible and industrial oilseed and vegetable crops as well as highly diverse wild germplasm (Warwick, 2011). The members of this family are distributed worldwide (Lysak and Koch, 2011). Many aspects of their genome evolution and the evolutionary trajectories that formed the crucifer species are not well understood. A sound phylogenetic classification is critical to understand the evolutionary relationships among distantly related crucifer species.

Methods
Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call