Synthesis of Nuclear and Chloroplast Data Combined With Network Analyses Supports the Polyploid Origin of the Apple Tribe and the Hybrid Origin of the Maleae-Gillenieae Clade
Plant biologists have debated the evolutionary origin of the apple tribe (Maleae; Rosaceae) for over a century. The "wide-hybridization hypothesis" posits that the pome-bearing members of Maleae (base chromosome number = 17) resulted from a hybridization and/or allopolyploid event between...
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Published in | Frontiers in plant science Vol. 12; p. 820997 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Switzerland
Frontiers Media S.A
25.01.2022
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Subjects | |
Online Access | Get full text |
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Summary: | Plant biologists have debated the evolutionary origin of the apple tribe (Maleae; Rosaceae) for over a century. The "wide-hybridization hypothesis" posits that the pome-bearing members of Maleae (base chromosome number
= 17) resulted from a hybridization and/or allopolyploid event between progenitors of other tribes in the subfamily Amygdaloideae with
= 8 and
= 9, respectively. An alternative "spiraeoid hypothesis" proposed that the
= 17 of Maleae arose via the genome doubling of
= 9 ancestors to
= 18, and subsequent aneuploidy resulting in
= 17. We use publicly available genomic data-448 nuclear genes and complete plastomes-from 27 species representing all major tribes within the Amygdaloideae to investigate evolutionary relationships within the subfamily containing the apple tribe. Specifically, we use network analyses and multi-labeled trees to test the competing wide-hybridization and spiraeoid hypotheses. Hybridization occurred between an ancestor of the tribe Spiraeeae (
= 9) and an ancestor of the clade Sorbarieae (
= 9) + Exochordeae (
= 8) + Kerrieae (
= 9), giving rise to the clade Gillenieae (
= 9) + Maleae (
= 17). The ancestor of the Maleae + Gillenieae arose via hybridization between distantly related tribes in the Amygdaloideae (i.e., supporting the wide hybridization hypothesis). However, some evidence supports an aspect of the spiraeoid hypothesis-the ancestors involved in the hybridization event were likely both
= 9, so genome doubling was followed by aneuploidy to result in
= 17 observed in Maleae. By synthesizing existing genomic data with novel analyses, we resolve the nearly century-old mystery regarding the origin of the apple tribe. Our results also indicate that nuclear gene tree-species tree conflict and/or cytonuclear conflict are pervasive at several other nodes in subfamily Amygdaloideae of Rosaceae. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Reviewed by: Natascha D. Wagner, University of Göttingen, Germany; Ofere Francis Emeriewen, Julius Kühn Institute (JKI), Germany This article was submitted to Plant Systematics and Evolution, a section of the journal Frontiers in Plant Science Edited by: Susann Wicke, Humboldt University of Berlin, Germany |
ISSN: | 1664-462X 1664-462X |
DOI: | 10.3389/fpls.2021.820997 |