Complete Chloroplast Sequence Research Articles

Complete Plastid Genome Sequences of Three Tropical African Beilschmiediineae Trees (Lauraceae: Crytocaryeae)

Millions of years of isolation have given Madagascar a unique flora that still reflects some of its relationship with the continents of Africa and India. Here, the complete chloroplast sequence of Beilschmiedia moratii, a tropical tree in Madagascar, was determined. The plastome, with a length of 158,410 bp, was 143 bp and 187 bp smaller than those of two closely related species, B. pierreana and Potameia microphylla, in sub-Saharan Africa and Madagascar with published sequences, respectively. A total of 124 repeats and 114 simple sequence repeats (SSRs) were detected in the plastome of B. moratii. Six highly variable regions, including ndhF, ndhF-rpl32, trnC-petN, pebE-petL, rpl32-trnL, and ycf1, among the three African species were identified and 1151 mutation events, including 14 SVs, 351 indels, and 786 substitutions, were accurately located. There were 634 mutation events between B. moratii and P. microphylla with a mean nucleotide variability (π) value of 0.00279, while there were 827 mutation events between B. moratii and B. pierreana with a mean π value of 0.00385. The Ka/Ks ratios of 86 protein-coding genes in the three African species were less than 1, and the mean value between B. moratii and P. microphylla was 0.184, while the mean value between B. moratii and B. pierreana was 0.286. In this study, the plastid genomes of the three African Beilschmiediineae species were compared for the first time and revealed that B. moratii and P. microphylla from Madagascar were relatively conserved, with low mutation rates and slower evolutionary rates.

The complete chloroplast genome of Nekemias hypoglauca (Hance) J. Wen & Z. L. Nie 2014 (Family: Vitaceae) and its phylogenetic analysis

Nekemias is a perennial woody vine with nine species that had been originally placed in Ampelopsis. These species of Nekemias are economically and medically important. Limited information is available on the genomic characteristics of the chloroplasts of this genus. Nekemias hypoglauca (Hance) J. Wen & Z. L. Nie 2014 contains 131 unique genes (86 protein-coding genes, 8 rRNAs, and 37 tRNAs). The complete chloroplast sequence contains 162,976 bp. The large single-copy region contains 89,291 bp; the small single-copy region contains 19,063 bp, and a pair of inverted repeat sequences is composed of 27,311 bp. There are 84 simple sequence repeat (SSR) loci in the complete chloroplast genome of N. hypoglauca, with mononucleotide, dinucleotide, trinucleotide, tetranucleotide and hexanucleotide SSRs of 58, 9, 6, 10 and 1, respectively. A total of 337 repeats were identified, including 172 forward repeats, three reverse repeats and 163 palindromic repeats. A phylogenetic analysis based on the complete genome data of the chloroplasts of 10 plant species indicated the monophyly of Nekemias and determined the phylogenetic relationships of N. hypoglauca in Nekemias. This study provides a reference for further studies on the taxonomy, identification, origin and evolution of N. hypoglauca and Nekemias.

Origin of domesticated water chestnuts (Trapa bispinosa Roxb.) and genetic variation in wild water chestnuts

AbstractThe water chestnut Trapa bispinosa Roxb. has been domesticated in China and has been reported as the only domesticated species of this genus. To understand the origin of T. bispinosa and its evolution pathway, we compared the genetic similarity and seed morphology of domesticated water chestnut T. bispinosa with three wild species T. natans, T. incisa, and T. japonica along with archeological seed samples from the Tianluoshan site (approximately 7000–6300 cal BP) in China. The largest seed size was observed only in the domesticated species, whereas other wild species showed smaller size including T. natans L. genetically close to the domesticated type, and T. incisa was the smallest in size. The volumes of the seed capsule and endosperm were measured using X ray CT scans, showing the ratios of total volumes between T. bispinosa and wild species ranged from 4.2 to 4.5. The ratios of endosperm volume ranged from 3.3 to 3.7. Both measurements showed domesticated species have larger seed volume. Genome size was indirectly estimated by flow cytometry. Domesticated species with larger seed size was estimated as diploid, as were the wild species except for tetraploid species T. japonica. Domesticated species clearly showed the largest edible organs, but it was not a result of ploidy level changes. Maternal lineages traced using complete whole chloroplast sequences, suggested that T. natans is the closest to T. bispinosa, both of which are close to T. japonica. The result was confirmed by PCR genotyping with chloroplast insertion/deletion (cpINDEL) markers developed in the study. T. incisa showed distinct plastid types within the species, and T. japonica showed a unique plastid genotype. Our study concludes the largest volumes for the edible endosperm have been accomplished through nearly 6000 years of artificial selection, but the domestication did not involve ploidy level changes.

Molecular classification of Barbeyaceae (Barbeya oleoides Schweinf.) using four different DNA barcodes

Despite many efforts to determine the phylogenetic relationship between Barbeyaceae and other families of Rosales, the sister relationship of this family has remained unclear. Barbeya oleoides, which is currently the only species in the family Barbeyaceae, and native to Somalia, Ethiopia, and the Arabian Peninsula were collected from Wadi Turbah Zahran northwestern of Al-Baha City, southwestern Saudi Arabia (20°14’N, 41°15’E). To study the sister relationship of Barbeyaceae and the other families of Rosales, the complete chloroplast sequences were used for phylogenetic analysis. In addition, four standard DNA barcodes (the internal transcribed spacer 2 (ITS2), ribulose 1,5-biphosphate carboxylase (rbcL), maturase K (matk), the intergenic spacer region (trnH-psbA)) were used to test for their quality in identifying phylogenetic relationship of the studied families. Sequence analysis of the complete chloroplast sequences showed that Rosales clade has two subclades and clearly discriminated all families within this order. This is the first report of a partial ITS2 locus sequence in B. oleoides. The partial ITS2, rbcL, matk, and gene sequences discriminate B. oleoides of the Barbeyaceae family from the closely related plant families: Cannabaceae, Rosaceae, Rhamnaceae, Urticaceae, Moraceae, Elaeagnaceae, Dirachmaceae, and Ulmaceae. In contrast, the partial trnH-psbA sequence of B. oleoides did not show any homology to the available DNA sequence of plant families in GenBank, suggesting that it is more suitable as DNA barcode for variations within one species.

Genomic exploration of Sesuvium sesuvioides: comparative study and phylogenetic analysis within the order Caryophyllales from Cholistan desert, Pakistan

BackgroundThe Aizoaceae family’s Sesuvium sesuvioides (Fenzl) Verdc is a medicinal species of the Cholistan desert, Pakistan. The purpose of this study was to determine the genomic features and phylogenetic position of the Sesuvium genus in the Aizoaceae family. We used the Illumina HiSeq2500 and paired-end sequencing to publish the complete chloroplast sequence of S. sesuvioides.ResultsThe 155,849 bp length cp genome sequence of S. sesuvioides has a 36.8% GC content. The Leucine codon has the greatest codon use (10.6%), 81 simple sequence repetitions of 19 kinds, and 79 oligonucleotide repeats. We investigated the phylogeny of the order Caryophyllales’ 27 species from 23 families and 25 distinct genera. The maximum likelihood tree indicated Sesuvium as a monophyletic genus, and sister to Tetragonia. A comparison of S. sesuvioides, with Sesuvium portulacastrum, Mesembryanthemum crystallinum, Mesembryanthemum cordifolium, and Tetragonia tetragonoides was performed using the NCBI platform. In the comparative investigation of genomes, all five genera revealed comparable cp genome structure, gene number and composition. All five species lacked the rps15 gene and the rpl2 intron. In most comparisons with S. sesuvioides, transition substitutions (Ts) were more frequent than transversion substitutions (Tv), producing Ts/Tv ratios larger than one, and the Ka/Ks ratio was lower than one. We determined ten highly polymorphic regions, comprising rpl22, rpl32-trnL-UAG, trnD-GUC-trnY-GUA, trnE-UUC-trnT-GGU, trnK-UUU-rps16, trnM-CAU-atpE, trnH-GUG-psbA, psaJ-rpl33, rps4-trnT-UGU, and trnF-GAA-ndhJ.ConclusionThe whole S. sesuvioides chloroplast will be examined as a resource for in-depth taxonomic research of the genus when more Sesuvium and Aizoaceae species are sequenced in the future. The chloroplast genomes of the Aizoaceae family are well preserved, with little alterations, indicating the family’s monophyletic origin. This study’s highly polymorphic regions could be utilized to build realistic and low-cost molecular markers for resolving taxonomic discrepancies, new species identification, and finding evolutionary links among Aizoaceae species. To properly comprehend the evolution of the Aizoaceae family, further species need to be sequenced.

The complete chloroplast genome sequence of Rosa ‘Limoncello’ (Rosales: Rosaceae)

Rosa ‘Limoncello’ finds applications in gardening and landscaping. In this study, we assembled and annotated the complete chloroplast genome of this variety for the first time. The length of its chloroplast genome was 156,493 bp, containing two short inverted repeat regions of 26,052 bp, each separated by a large single-copy region of 85,649 bp and a small single-copy region of 18,740 bp. The chloroplast DNA of R. ‘Limoncello’ consisted of 135 genes, including 90 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. On comparing the complete chloroplast sequence of R. ‘Limoncello’ with that of other Rosa species, R. ‘Limoncello’ was found to be closely related to Rosa cymosa. Thus, information on the chloroplast genome sequence of this rose variety can facilitate phylogenetic studies of the genus Rosa.

Characterization and phylogenetic analysis of the complete chloroplast genome of Saussurea sagittifolia (Asteraceae, Cardueae)

The species of Saussurea sagittifolia Y. S. Chen & S. R. Yi belongs to the family Asteraceae (Cardueae). The complete chloroplast genome of S. sagittifolia was assembled and annotated for the first time in this study. The complete chloroplast genome of S. sagittifolia was 152,535 bp, including a large single-copy (LSC) region of 83,511 bp, a small single-copy (SSC) region of 18,632 bp, and a pair of inverted repeats (IRs) of 25,196 bp. The overall GC content of the chloroplast genome was 37.7%. The chloroplast genome encoded 131 genes, including 87 protein-coding genes, 36 tRNA genes, and eight rRNA genes. Phylogenetic analysis based on complete chloroplast sequences revealed that it related closely to Saussurea medusa.

The complete chloroplast genome of Chloranthus nervosus Collett ex Hemsl. 1890 (Chloranthaceae)

In this study, we sequenced and assembled the complete chloroplast genome of Chloranthus nervosus Collett ex Hemsl. 1890. The total length of the complete chloroplast sequence was found to be 158,002 bp. It consisted of a large single-copy (LSC) region of 87,127 bp, a small single-copy (SSC) region of 18,541 bp, and a pair of inverted repeat (IR) regions, each with a length of 26,167 bp. The overall GC content of the complete chloroplast genome was 38.9%, with the LSC region, SSC region, and IR regions exhibiting GC contents of 37.4%, 34.1%, and 43.1%, respectively. The annotation of the chloroplast genome revealed a total of 131 genes, comprising 86 protein-coding genes, 37 tRNA genes, and eight rRNA genes. Phylogenetic analysis revealed that the seven sampled species of Chloranthus were divided into two clades. Within the clade characterized by long filamentous anther connectives, C. nervosus showed the closest relation to C. japonicus. These findings validated the previous preliminary results on the phylogenetic relationships of the seven species of Chloranthus with strong support.

Complete chloroplast genome sequence of Adenostemma madurense (Asteraceae)

Adenostemma madurense D.C. belongs to the family Asteraceae and is a wild annual herb found in Korea. In this study, we determined the phylogenetic position of A. madurense by identifying its complete chloroplast sequence. The result indicated a genome size of 150,054 bp, which was composed of a large single copy of 82,008 bp, two inverted repeats of 24,952 bp each, and a small singlecopy of 18,142 bp. Overall, 128 unique genes were identified, including 85 protein-coding, 35 tRNA, and 8 rRNA genes. A comparison of the A. madurense and A. lavenia chloroplast genomes revealed seven variations. Phylogenetic analysis revealed that A. madurense formed a clade with A. lavenia and had a well-supported phylogenetic relationship with Asteraceae. The first complete chloroplast genome of A. madurense was obtained, which would be helpful in explaining the process of speciation in Adenostemma and the development of molecular markers.

Variation in Chloroplast Genome Size: Biological Phenomena and Technological Artifacts.

The development of bioinformatic solutions is guided by biological knowledge of the subject. In some cases, we use unambiguous biological models, while in others we rely on assumptions. A commonly used assumption for genomes is that related species have similar genome sequences. This is even more obvious in the case of chloroplast genomes due to their slow evolution. We investigated whether the lengths of complete chloroplast sequences are closely related to the taxonomic proximity of the species. The study was performed using all available RefSeq sequences from the asterid and rosid clades. In general, chloroplast length distributions are narrow at both the family and genus levels. In addition, clear biological explanations have already been reported for families and genera that exhibit particularly wide distributions. The main factors responsible for the length variations are parasitic life forms, IR loss, IR expansions and contractions, and polyphyly. However, the presence of outliers in the distribution at the genus level is a strong indication of possible inaccuracies in sequence assembly.

Complete chloroplast genome of the oil-bearing shrub Staphylea bumalda DC (Staphyleaceae)

Staphylea bumalda DC, belonging to family Staphyleaceae, is a woody understory tree that is both edible and medicinal and produces oil with high economic value. This study reports the first complete chloroplast genome sequence of S. bumalda. The complete chloroplast genome sequence of S. bumalda is 160,319 bp in length with an overall GC content of 32.79%, which is composed of a large single-copy region (LSC: 89,401 bp), a small single-copy region (SSC: 18,834 bp), and two inverted repeat regions (IR: 26,042 bp). A total of 130 genes were predicted in this genome, including 85 protein-coding genes, 37 tRNA genes, and eight rRNA genes. The phylogenetic analysis based on 14 complete chloroplast sequences from related species revealed that S. bumalda is a sister to S. holocarpa.

The complete chloroplast genome of the endangered species garra de león [Bomarea ovallei (Phil.) Ravenna] from Chile

Bomarea ovallei (Phil.) Ravenna (2n=2x=18) is an endangered endemic species that inhabits only a small part of the coast of the Atacama region. We describe the structure, gene composition and phylogeny of the complete chloroplast sequence of this elusive species. The chloroplast genome consists of 155,018 bp, with typical quadripartite structures: a large single copy region (LSC) of 84,132 bp, a small single copy region (SSC) of 17,794 bp, and two inverted repeat regions (IRs) contain 26,546 bp. One hundred and thirty-four genes were identified out of which 84 coding genes, 8 rRNA, 38 tRNA and 4 pseudogenes. B. ovallei chloroplast resembles chloroplasts from seven species of the order Liliales in length and structure and is most similar to Bomarea edulis (BP=100). The average nucleotide variability (Pi) of 0.00254 between these two Bomarea species is moderate. Nine loci with increased variability were identified: rps16-trnQ, atpF, trnL, ndhC-trnV, rbcL, psbJ, rpl32-trnL, ndhD and ycf1. These loci could be used as DNA markers for classification and evaluation studies in Bomarea populations.

Evolutionary Comparison of the Complete Chloroplast Genomes in Convallaria Species and Phylogenetic Study of Asparagaceae.

The genus Convallaria (Asparagaceae) comprises three herbaceous perennial species that are widely distributed in the understory of temperate deciduous forests in the Northern Hemisphere. Although Convallaria species have high medicinal and horticultural values, studies related to the phylogenetic analysis of this genus are few. In the present study, we assembled and reported five complete chloroplast (cp) sequences of three Convallaria species (two of C. keiskei Miq., two of C. majalis L., and one of C. montana Raf.) using Illumina paired-end sequencing data. The cp genomes were highly similar in overall size (161,365–162,972 bp), and all consisted of a pair of inverted repeats (IR) regions (29,140–29,486 bp) separated by a large single-copy (LSC) (85,183–85,521 bp) and a small single-copy (SSC) region (17,877–18,502 bp). Each cp genome contained the same 113 unique genes, including 78 protein-coding genes, 30 transfer RNA genes, and 4 ribosomal RNA genes. Gene content, gene order, AT content and IR/SC boundary structure were nearly identical among all of the Convallaria cp genomes. However, their lengths varied due to contraction/expansion at the IR/LSC borders. Simple sequence repeat (SSR) analyses indicated that the richest SSRs are A/T mononucleotides. Three highly variable regions (petA-psbJ, psbI-trnS and ccsA-ndhD) were identified as valuable molecular markers. Phylogenetic analysis of the family Asparagaceae using 48 cp genome sequences supported the monophyly of Convallaria, which formed a sister clade to the genus Rohdea. Our study provides a robust phylogeny of the Asparagaceae family. The complete cp genome sequences will contribute to further studies in the molecular identification, genetic diversity, and phylogeny of Convallaria.

Chloroplast Genome Annotation Tools: Prolegomena to the Identification of Inverted Repeats.

The development of next-generation sequencing technology and the increasing amount of sequencing data have brought the bioinformatic tools used in genome assembly into focus. The final step of the process is genome annotation, which works on assembled genome sequences to identify the location of genome features. In the case of organelle genomes, specialized annotation tools are used to identify organelle genes and structural features. Numerous annotation tools target chloroplast sequences. Most chloroplast DNA genomes have a quadripartite structure caused by two copies of a large inverted repeat. We investigated the strategies of six annotation tools (Chloë, Chloroplot, GeSeq, ORG.Annotate, PGA, Plann) for identifying inverted repeats and analyzed their success using publicly available complete chloroplast sequences of taxa belonging to the asterid and rosid clades. The annotation tools use two different approaches to identify inverted repeats, using existing general search tools or implementing stand-alone solutions. The chloroplast sequences studied show that there are different types of imperfections in the assembled data and that each tool performs better on some sequences than the others.

The First Complete Chloroplast Genome Sequence and Phylogenetic Analysis of Pistachio (Pistacia vera)

Pistachio is one of the most economically important nut crops worldwide. However, there are no reports describing the chloroplast genome of this important fruit tree. In this investigation, we assembled and characterized the complete pistachio chloroplast sequence. The Pistacia vera chloroplast genome was 160,598 bp in size, similar to other members of Anacardiaceae (149,011–172,199 bp) and exhibited the typical four section structure, including a large single copy region (88,174 bp), a small single copy region (19,330 bp), and a pair of inverted repeats regions (26,547 bp). The genome contains 121 genes comprised of 87 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Thirteen intron-containing genes were identified in the genome wherein two genes had more than two introns. The genomic patterns of GC content resembled those for other Anacardiaceae. P. vera displayed the highest number of simple sequence repeats (SSRs) among the genera studied, which may be useful for molecular marker development and future population studies. Amino acid analysis revealed that Leucine is the most frequent (10.69%) amino acid in the chloroplast genome followed by Isoleucine (8.53%) and Serine (7.77%). Cysteine (1.30%) and Tryptophan (1.74%) were the least frequent amino acids. Phylogenetic analysis revealed P. vera is most like its taxonomically close relative P. weinmaniifolia, followed by Rhus chinensis; all placed taxonomically in the tribe Rhoeae. Members of Anacardiaceae were most closely related to Rhoeae, followed by members of Spondieae. The reports of this chloroplast genome will be useful for future conservation studies, genetic evaluation and breeding of P. vera, and more comprehensive phylogenetic analysis of the Pistacia species and its closely-related genera.

Characterization of the Complete Chloroplast Genome Sequence of the Socotra Dragon`s Blood Tree (Dracaena cinnabari Balf.)

The Socotra dragon`s blood tree (Dracaena cinnabari Balf.) is endemic to the island of Socotra in Yemen. This iconic species plays an essential role in the survival of associated organisms, acting as an umbrella tree. Overexploitation, overgrazing by livestock, global climate change, and insufficient regeneration mean that the populations of this valuable species are declining in the wild. Although there are many studies on the morphology, anatomy, and physiology of D. cinnabari, no genomic analysis of this endangered species has been performed so far. Therefore, the main aim of this study was to characterize the complete chloroplast sequence genome of D. cinnabari for conservation purposes. The D. cinnabari chloroplast genome is 155,371 bp with a total GC content of 37.5%. It has a quadripartite plastid genome structure composed of one large single-copy region of 83,870 bp, one small single-copy region of 18,471 bp, and two inverted repeat regions of 26,515 bp each. One hundred and thirty-two genes were annotated, 86 of which are protein-coding genes, 38 are transfer RNAs, and eight are ribosomal RNAs. Forty simple sequence repeats have also been identified in this chloroplast genome. Comparative analysis of complete sequences of D. cinnabari chloroplast genomes with other species of the genus Dracaena showed a very high conservativeness of their structure and organization. Phylogenetic inference showed that D. cinnabari is much closer to D. draco, D. cochinchinensis, and D. cambodiana than to D. terniflora, D. angustifolia, D. hokouensis, and D. elliptica. The results obtained in this study provide new and valuable omics data for further phylogenetic studies of the genus Dracaena as well as enable the protection of genetic resources of highly endangered D. cinnabari.

Genome diploidization associates with cladogenesis, trait disparity, and plastid gene evolution.

Angiosperm genome evolution was marked by many clade-specific whole-genome duplication events. The Microlepidieae is one of the monophyletic clades in the mustard family (Brassicaceae) formed after an ancient allotetraploidization. Postpolyploid cladogenesis has resulted in the extant c. 17 genera and 60 species endemic to Australia and New Zealand (10 species). As postpolyploid genome diploidization is a trial-and-error process under natural selection, it may proceed with different intensity and be associated with speciation events. In Microlepidieae, different extents of homoeologous recombination between the two parental subgenomes generated clades marked by slow ("cold") versus fast ("hot") genome diploidization. To gain a deeper understanding of postpolyploid genome evolution in Microlepidieae, we analyzed phylogenetic relationships in this tribe using complete chloroplast sequences, entire 35S rDNA units, and abundant repetitive sequences. The four recovered intra-tribal clades mirror the varied diploidization of Microlepidieae genomes, suggesting that the intrinsic genomic features underlying the extent of diploidization are shared among genera and species within one clade. Nevertheless, even congeneric species may exert considerable morphological disparity (e.g. in fruit shape), whereas some species within different clades experience extensive morphological convergence despite the different pace of their genome diploidization. We showed that faster genome diploidization is positively associated with mean morphological disparity and evolution of chloroplast genes (plastid-nuclear genome coevolution). Higher speciation rates in perennials than in annual species were observed. Altogether, our results confirm the potential of Microlepidieae as a promising subject for the analysis of postpolyploid genome diploidization in Brassicaceae.

The complete chloroplast genome sequence of Ranunculus pekinensis (L. Liou) Luferov (Ranunculaceae), a species endemic to China

Ranunculus pekinensis (L. Liou) Luferov 1997, a perennial aquatic herb, is endemic to Beijing, China and has high water quality requirements. Because its habitat is under great threat and its population is declining, it is now listed as a national protected plant in China. To provide genomic resources for future research of this endangered species, the complete chloroplast genome sequence of R. pekinensis was assembled and annotated for the first time. The complete chloroplast genome sequence was 156,139 bp in length, containing a large single copy region (LSC) of 85,430 bp and a small single copy region (SSC) of 19,970 bp, which were separated by a pair of 25,367 bp inverted repeat regions (IRs). The complete chloroplast sequence contained 112 unique genes, including 30 tRNA, 4 rRNA, and 78 protein-coding genes. The overall guanine-cytosine (GC) content of the chloroplast genome was 37.8%, and the GC contents of the LSC, SSC, and IR regions were 36.0%, 31.3%, and 43.5%, respectively. Phylogenetic analysis with the reported chloroplast sequences showed that R. pekinensis was closely related to R. bungei Steud. 1841, both of which belonged to Ranunculus Sect. Batrachium DC. 1817. These data will provide essential resources regarding the evolution and conservation of R. pekinensis.

The complete chloroplast genome of the newly recorded species Tainia acuminata Averyanov (Orchidaceae) from China

The complete chloroplast genome sequence of Tainia acuminata Averyanov was assembled and the phylogenetic relationship of the species to other taxa in Subtrib. Bletlinae was inferred in this study. The length of the complete chloroplast sequence is 157,603 bp, and it contains a large single-copy (LSC) region of 86,336 bp, a small single-copy (SSC) region of 18,129 bp, and two inverted repeat (IRA and IRB) regions of 26,569 bp. A total of 134 genes were annotated including 89 protein-coding genes, 37 tRNA, and eight rRNA. Phylogenetic analysis showed that T. acuminata was closely related to T. cordifolia, and the genus was closely related to a clade consisting of Calanthe, Phaius, and Cephalantheropsis.

Genomes, repeatomes and interphase chromosome organization in the meadowfoam family (Limnanthaceae, Brassicales)

SUMMARYThe meadowfoam family (Limnanthaceae) is one of the smallest and genomically underexplored families of the Brassicales. The Limnanthaceae harbor about seven species in the genus Limnanthes (meadowfoam) and Floerkea proserpinacoides (false mermaidweed), all native to North America. Because all Limnanthes and Floerkea species have only five chromosome pairs, i.e., a chromosome number rare in Brassicales and shared with Arabidopsis thaliana (Arabidopsis), we examined the Limnanthaceae genomes as a potential model system. Using low‐coverage whole‐genome sequencing data, we reexamined phylogenetic relationships and characterized the repeatomes of Limnanthaceae genomes. Phylogenies based on complete chloroplast and 35S rDNA sequences corroborated the sister relationship between Floerkea and Limnanthes and two major clades in the latter genus. The genome size of Limnanthaceae species ranges from 1.5 to 2.1 Gb, apparently due to the large increase in DNA repeats, which constitute 60–70% of their genomes. Repeatomes are dominated by long terminal repeat retrotransposons, while tandem repeats represent only less than 0.5% of the genomes. The average chromosome size in Limnanthaceae species (340–420 Mb) is more than 10 times larger than in Arabidopsis (32 Mb). A three‐dimensional fluorescence in situ hybridization analysis demonstrated that the five chromosome pairs in interphase nuclei of Limnanthes species adopt the Rabl‐like configuration.