Maternal Inheritance of U’s Triangle and Evolutionary Process of Brassica Mitochondrial Genomes

Abstract

The sequences and genomic structures of plant mitochondrial (mt) genomes provide unique material for phylogenetic studies. The nature of uniparental inheritance renders an advantage when utilizing mt genomes for determining the parental sources of hybridized taxa. In this study, a concatenated matrix of mt genes was used to infer the phylogenetic relationships of six cultivated Brassica taxa and explore the maternal origins of three allotetraploids. The well-resolved sister relationships between two pairs of diploid and allotetraploid taxa suggest that Brassica carinata (car) possessed a maternal origin from Brassica nigra, while Brassica juncea (jun) was maternally derived from Brassica rapa (cam). Another allotetraploid taxon, Brassica napus (cv. Wester) may have been maternally derived from the common ancestor of B. rapa and Brassica oleracea (ole), and/or have undergone (an) extra hybridization event(s) along its evolutionary history. The characteristics of Brassica mt genomic structures also supported the phylogenetic results. Sinapis arvensis was nested inside the Brassica species, sister to the B. nigra-B. carinata lineage, and possessed an mt genome structure that mostly resembled B. nigra. Collectively, the evidence supported a systematic revision that placed S. arvensis within Brassica. Finally, ancestral mt genomes at each evolutionary node of Brassica were reconstructed, and the detailed and dynamic evolution of Brassica mt genomes was successfully reproduced. The mt genome of B. nigra structurally resembled that of the Brassica ancestor the most, with only one reversion of a block, and the Brassica oleracea underwent the most drastic changes. These findings suggested that repeat-mediated recombinations were largely responsible for the observed structural variations in the evolutionary history of Brassica mt genomes.

Shotgun proteomics of Brassica rapa seed proteins identifies vicilin as a major seed storage protein in the mature seed

“…carinata (BC genome), B . rapa is a diploid species and contains only the Brassica A genome [ 17 , 18 ]. In addition to oilseed crops (subsp.…”

Genomics Armed With Diversity Leads the Way in Brassica Improvement in a Changing Global Environment

“…Due to its small size in comparison with other higher plants, the Brassica mt genome was used as an early model in the understanding the plant mt, structure, function, and content (Grewe et al, 2014 ). Comparative analysis of the mt genome can be used to study interspecific phylogenetic relationships (Darracq et al, 2011 ) and uncover the plant's evolutionary history (Xue et al, 2020 ). For example, the mt genomes of Brassica rapa subspecies with distinct morphologies were found to be highly conserved (Hatono et al, 2017 ).…”

“…Furthermore, the rate of mutation for Brassica mt DNA was four times slower than that of the chloroplast (Cp) DNA (Palmer and Herbon, 1988 ). Xue et al ( 2020 ) compared mt DNA of the six members of the U triangle (Nagaharu et al, 1935 ) and revealed that B. oleracea was undergoing the most mt genomic change, while the B-genomes containing Brassica carinata and Brassica nigra were identified as maternally more distantly related to the remaining Brassica accessions of the U triangle (Xue et al, 2020 ). It was also suggested that Sinapis arvensis could have been misclassified based on both phylogenetic and mt genomic organization, placing it within the Brassica species and sister to the B. nigra–B.…”

“…It was also suggested that Sinapis arvensis could have been misclassified based on both phylogenetic and mt genomic organization, placing it within the Brassica species and sister to the B. nigra–B. carinata lineage (Sang et al, 2020 ; Xue et al, 2020 ). Sang et al ( 2020 ) also confirmed that the genome structure and evolutionary analysis of the S. arvensis organellar genomes were more similar to those of B. nigra and B. carinata .…”

Phylogenomic analyses of the East Asian endemicAbelia(Caprifoliaceae) shed insights into the temporal and spatial diversification history with widespread hybridizations

“…Chloroplast DNA inheritance is primarily from the maternal parent in most angiosperms, therefore it cannot resolve the entire phylogenetic history of lineages (Corriveau and Coleman, 1988; Birky, 1995; Xue et al, 2020). Target enrichment has shown to be an effective approach to extract orthologous nuclear genes and can infer the phylogenetic relationships of complex taxa successfully (e.g., Helianthus L., Stephens et al, 2015.…”