Abstract
The study of domestication contributes to our knowledge of evolution and crop genetic resources. Human selection has shaped wild Brassica rapa into diverse turnip, leafy, and oilseed crops. ...Despite its worldwide economic importance and potential as a model for understanding diversification under domestication, insights into the number of domestication events and initial crop(s) domesticated in B. rapa have been limited due to a lack of clarity about the wild or feral status of conspecific noncrop relatives. To address this gap and reconstruct the domestication history of B. rapa, we analyzed 68,468 genotyping-by-sequencing-derived single nucleotide polymorphisms for 416 samples in the largest diversity panel of domesticated and weedy B. rapa to date. To further understand the center of origin, we modeled the potential range of wild B. rapa during the mid-Holocene. Our analyses of genetic diversity across B. rapa morphotypes suggest that noncrop samples from the Caucasus, Siberia, and Italy may be truly wild, whereas those occurring in the Americas and much of Europe are feral. Clustering, tree-based analyses, and parameterized demographic inference further indicate that turnips were likely the first crop type domesticated, from which leafy types in East Asia and Europe were selected from distinct lineages. These findings clarify the domestication history and nature of wild crop genetic resources for B. rapa, which provides the first step toward investigating cases of possible parallel selection, the domestication and feralization syndrome, and novel germplasm for Brassica crop improvement.
Brassica napus, an allotetraploid crop, is hypothesized to be a hybrid from unknown varieties of Brassica rapa and Brassica oleracea. Despite the economic importance of B. napus, much is unresolved ...regarding its phylogenomic relationships, genetic structure, and diversification. Here we conduct a comprehensive study among diverse accessions from 183 B. napus (including rapeseed, rutabaga, and Siberian kale), 112 B. rapa, and 62 B. oleracea and its wild relatives. Using RNA-seq of B. napus accessions, we define the genetic diversity and sub-genome variance of six genetic clusters. Nuclear and organellar phylogenies for B. napus and its progenitors reveal varying patterns of inheritance and post-formation introgression. We discern regions with signatures of selective sweeps and detect 8,187 differentially expressed genes with implications for B. napus diversification. This study highlights the complex origin and evolution of B. napus providing insights that can further facilitate B. napus breeding and germplasm preservation.
Duplication events are regarded as sources of evolutionary novelty, but our understanding of general trends for the long-term trajectory of additional genomic material is still lacking. Organisms ...with a history of whole genome duplication (WGD) offer a unique opportunity to study potential trends in the context of gene retention and or loss, gene and network dosage, and changes in gene expression. In this review, we discuss the prevalence of polyploidy across the tree of life, followed by an overview of studies investigating genome evolution and gene expression. We then provide an overview of methods in network biology, phylogenomics, and population genomics that are critical for advancing our understanding of evolution post-WGD, highlighting the need for models that can accommodate polyploids. Finally,
we close with a brief note on the importance of random processes in the evolution of polyploids with respect to neutral versus selective forces, ancestral polymorphisms, and the formation of autopolyploids versus allopolyploids.
Abstract
Modern agriculture depends on a narrow variety of crop species, leaving global food and nutritional security highly vulnerable to the adverse effects of climate change and population ...expansion. Crop improvement using conventional and molecular breeding approaches leveraging plant genetic diversity using crop wild relatives (CWRs) has been one approach to address these issues. However, the rapid pace of the global change requires additional innovative solutions to adapt agriculture to meet global needs. Neodomestication—the rapid and targeted introduction of domestication traits using introgression or genome editing of CWRs—is being explored as a supplementary approach. These methods show promise; however, they have so far been limited in efficiency and applicability. We propose expanding the scope of neodomestication beyond truly wild CWRs to include feral crops as a source of genetic diversity for novel crop development, in this case ‘redomestication’. Feral crops are plants that have escaped cultivation and evolved independently, typically adapting to their local environments. Thus, feral crops potentially contain valuable adaptive features while retaining some domestication traits. Due to their genetic proximity to crop species, feral crops may be easier targets for de novo domestication (i.e. neodomestication via genome editing techniques). In this review, we explore the potential of de novo redomestication as an application for novel crop development by genome editing of feral crops. This approach to efficiently exploit plant genetic diversity would access an underutilized reservoir of genetic diversity that could prove important in support of global food insecurity in the face of the climate change.
Feral populations, those which successfully persist outside of cultivation or husbandry, provide unique opportunities to study the genomic impacts of domestication and local adaptation. We argue that ...by leveraging genomic resources designed for domestic counterparts, powerful phylogenetic and population genomic data collection and analyses can be designed to disentangle complex demographic processes.
Abstract
Each year, SARS-CoV-2 is infecting an increasingly unprecedented number of species. In the present article, we combine mammalian phylogeny with the genetic characteristics of isolates found ...in mammals to elaborate on the host-range potential of SARS-CoV-2. Infections in nonhuman mammals mirror those of contemporary viral strains circulating in humans, although, in certain species, extensive viral circulation has led to unique genetic signatures. As in other recent studies, we found that the conservation of the ACE2 receptor cannot be considered the sole major determinant of susceptibility. However, we are able to identify major clades and families as candidates for increased surveillance. On the basis of our findings, we argue that the use of the term panzootic could be a more appropriate term than pandemic to describe the ongoing scenario. This term better captures the magnitude of the SARS-CoV-2 host range and would hopefully inspire inclusive policy actions, including systematic screenings, that could better support the management of this worldwide event.
Phytochemical diversity is thought to result from coevolutionary cycles as specialization in herbivores imposes diversifying selection on plant chemical defenses. Plants in the speciose genus
...(Brassicaceae) produce both ancestral glucosinolates and evolutionarily novel cardenolides as defenses. Here we test macroevolutionary hypotheses on co-expression, co-regulation, and diversification of these potentially redundant defenses across this genus. We sequenced and assembled the genome of
and foliar transcriptomes of 47 additional
species to construct a phylogeny from 9868 orthologous genes, revealing several geographic clades but also high levels of gene discordance. Concentrations, inducibility, and diversity of the two defenses varied independently among species, with no evidence for trade-offs. Closely related, geographically co-occurring species shared similar cardenolide traits, but not glucosinolate traits, likely as a result of specific selective pressures acting on each defense. Ancestral and novel chemical defenses in
thus appear to provide complementary rather than redundant functions.
Abstract
Understanding the evolutionary history of crops, including identifying wild relatives, helps to provide insight for conservation and crop breeding efforts. Cultivated Brassica oleracea has ...intrigued researchers for centuries due to its wide diversity in forms, which include cabbage, broccoli, cauliflower, kale, kohlrabi, and Brussels sprouts. Yet, the evolutionary history of this species remains understudied. With such different vegetables produced from a single species, B. oleracea is a model organism for understanding the power of artificial selection. Persistent challenges in the study of B. oleracea include conflicting hypotheses regarding domestication and the identity of the closest living wild relative. Using newly generated RNA-seq data for a diversity panel of 224 accessions, which represents 14 different B. oleracea crop types and nine potential wild progenitor species, we integrate phylogenetic and population genetic techniques with ecological niche modeling, archaeological, and literary evidence to examine relationships among cultivars and wild relatives to clarify the origin of this horticulturally important species. Our analyses point to the Aegean endemic B. cretica as the closest living relative of cultivated B. oleracea, supporting an origin of cultivation in the Eastern Mediterranean region. Additionally, we identify several feral lineages, suggesting that cultivated plants of this species can revert to a wild-like state with relative ease. By expanding our understanding of the evolutionary history in B. oleracea, these results contribute to a growing body of knowledge on crop domestication that will facilitate continued breeding efforts including adaptation to changing environmental conditions.
Evolutionary insights into plant breeding Turner-Hissong, Sarah D; Mabry, Makenzie E; Beissinger, Timothy M ...
Current opinion in plant biology,
04/2020, Letnik:
54
Journal Article
Recenzirano
Odprti dostop
Display omitted
•Population genetics can inform breeding strategies to increase genetic gain.•Genomic regions with selective sweeps are promising targets to introgress diversity.•Demography ...determines genetic architecture and deleterious load.•Deleterious alleles can either be purged via selection or masked via hybridization.•Gene editing enables rapid, precise introgression and de novo domestication.
Crop domestication is a fascinating area of study, as shown by a multitude of recent reviews. Coupled with the increasing availability of genomic and phenomic resources in numerous crop species, insights from evolutionary biology will enable a deeper understanding of the genetic architecture and short-term evolution of complex traits, which can be used to inform selection strategies. Future advances in crop improvement will rely on the integration of population genetics with plant breeding methodology, and the development of community resources to support research in a variety of crop life histories and reproductive strategies. We highlight recent advances related to the role of selective sweeps and demographic history in shaping genetic architecture, how these breakthroughs can inform selection strategies, and the application of precision gene editing to leverage these connections.
Cryptantha, an herbaceous plant genus of the Boraginaceae, subtribe Amsinckiinae, has an American amphitropical disjunct distribution, found in western North America and western South America, but ...not in the intervening tropics. In a previous study, Cryptantha was found to be polyphyletic and was split into five genera, including a weakly supported, potentially non-monophyletic Cryptantha s. s. In this and subsequent studies of the Amsinckiinae, interrelationshipswithin Cryptantha were generally not strongly supported and sample size was generally low. Here we analyze a greatly increased sampling of Cryptantha taxa using high-throughput, genome skimming data, in which we obtained the complete ribosomal cistron, the nearly complete chloroplast genome, and twenty-three mitochondrial genes. Our analyses have allowed for inference of clades within this complex with strong support. The occurrence of a non-monophyletic Cryptantha is confirmed, with three major clades obtained, termed here the Johnstonella/Albidae clade, the Maritimae clade, and a large Cryptantha core clade, each strongly supported as monophyletic. From these phylogenomic analyses, we assess the classification, character evolution, and phylogeographic history that elucidates the current amphitropical distribution of the group. Revealing the timing, direction, and number of times of dispersal between North and South America gives insight as to the origin of the great biodiversity of these regions.
PDF
