Re-exploration of U’s Triangle Brassica Species Based on Chloroplast Genomes and 45S nrDNA Sequences

Re-exploration of U’s Triangle Brassica Species Based on Chloroplast Genomes and 45S nrDNA Sequences

Abstract The concept of U’s triangle, which revealed the importance of polyploidization in plant genome evolution, described natural allopolyploidization events in Brassica using three diploids [B. rapa (A genome), B. nigra (B), and B. oleracea (C)] and derived allotetraploids [B. juncea (AB genome)...

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Auteurs principaux: Chang-Kug Kim, Young-Joo Seol, Sampath Perumal, Jonghoon Lee, Nomar Espinosa Waminal, Murukarthick Jayakodi, Sang-Choon Lee, Seungwoo Jin, Beom-Soon Choi, Yeisoo Yu, Ho-Cheol Ko, Ji-Weon Choi, Kyoung-Yul Ryu, Seong-Han Sohn, Isobel Parkin, Tae-Jin Yang
Format: article
Langue:EN
Publié: Nature Portfolio 2018
Sujets:
Medicine
R
Science
Q
Accès en ligne:https://doaj.org/article/e5ee3fece8a349868271b64d8c7b9835
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Résumé:Abstract The concept of U’s triangle, which revealed the importance of polyploidization in plant genome evolution, described natural allopolyploidization events in Brassica using three diploids [B. rapa (A genome), B. nigra (B), and B. oleracea (C)] and derived allotetraploids [B. juncea (AB genome), B. napus (AC), and B. carinata (BC)]. However, comprehensive understanding of Brassica genome evolution has not been fully achieved. Here, we performed low-coverage (2–6×) whole-genome sequencing of 28 accessions of Brassica as well as of Raphanus sativus [R genome] to explore the evolution of six Brassica species based on chloroplast genome and ribosomal DNA variations. Our phylogenomic analyses led to two main conclusions. (1) Intra-species-level chloroplast genome variations are low in the three allotetraploids (2~7 SNPs), but rich and variable in each diploid species (7~193 SNPs). (2) Three allotetraploids maintain two 45SnrDNA types derived from both ancestral species with maternal dominance. Furthermore, this study sheds light on the maternal origin of the AC chloroplast genome. Overall, this study clarifies the genetic relationships of U’s triangle species based on a comprehensive genomics approach and provides important genomic resources for correlative and evolutionary studies.

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