Genome-wide selection footprints and deleterious variations in young Asian allotetraploid rapeseed

Abstract

Brassica napus (AACC, 2n=38), is an important oilseed crop grown worldwide.However, little is known about the population evolution of this species, the genomic difference between its major genetic clusters, such as European and Asian rapeseed, and impacts of historical large-sale introgression events in this young tetraploid. In this study, we reported the de novo assembly of the genome sequences of an Asian rapeseed (B. napus), Ningyou 7 and its four progenitors and carried out de novo assembly-based comparison, pedigree and population analysis with other available genomic data from diverse European and Asian cultivars. Our results showed that Asian rapeseed originally derived from European rapeseed, but it had subsequently significantly diverged, with rapid genome differentiation after intensive local breeding selection. The first historical introgression of B. rapa dramatically broadened the allelic pool of Asian B. napus, but decreased their deleterious variations. The secondary historical introgression of European rapeseed (canola-quality) has reshaped Asian rapeseed into two groups, accompanied by an increase in genetic load. This study demonstrates distinctive genomic footprints by recent intra-and inter-species introgression events for local adaptation, and provide novel insights for understanding the rapid genome evolution of a young allopolyploid crop.

High‐density genetic variation maps reveal the correlation between asymmetric interspecific introgressions and improvement of agronomic traits in Upland and Pima cotton varieties developed in Xinjiang, China

“…Potential mechanisms may exist in this asymmetrical introgression phenomenon. Introgression is commonplace in animals and plants and is related to environmental adaptation and trait improvement (Lucek et al, 2014;Ai et al, 2015;Clark et al, 2015;Zhang et al, 2016;Zou et al, 2019). Therefore, we hypothesised that the asymmetrical introgression mechanism in cotton species may relate to adaptability.…”

Genome-wide identification and characterization of SnRK family genes in Brassica napus

“…Here, 25 BnSnRK3.71/3.72) were found located less than 200 kb. However, the identities of these gene pairs were less than 70%, indicating they were not tandem duplication events.…”

Genome-wide identification and characterization of SnRK family genes in Brassica napus

“…We also analyzed the occurrence of the tandem duplication events. Here, 25 .71/3.72) were found located less than 200 kb. However, the identities of these gene pairs were less than 70%, indicating they were not tandem duplication events.…”

“…Brassica napus is an important oil crop in the world. Recently, the genomes of Darmor-bzh (winter ecotype), Zhongshuang 11 and NY7 (seni-winter ecotype) were successfully sequenced and assembled (Chalhoub et al, 2014;Sun et al, 2017;Zou et al, 2019); however, the systematic analysis of BnSnRK gene family has been not well reported. In this study, 114 SnRK gene members were identi ed in the B.napus genome.…”