Complete chloroplast genome sequences of Solanum commersonii and its application to chloroplast genotype in somatic hybrids with Solanum tuberosum

An international breeding project using a wild potato relative Solanum commersonii resulted in two new frost-tolerant native potato cultivars for the Andes and the Altiplano

This breeding project, initiated at the United States Potato Genebank (USPG) in collaboration with Peruvian partners Instituto Nacional de Innovacion Agraria (INIA), International Potato Center, Peru (CIP), and local farmers, sought to enhance cold hardiness and frost tolerance in native potato cultivars in Peru. The Andes and Altiplano are often affected by frost, which causes significant reduction in yield; creating varieties with superior resilience is a critical undertaking. The goal was to transfer outstanding non-acclimated cold tolerance and acclimation capacity found in wild potato species Solanum commersonii (cmm). Breeding families segregating for cold hardiness were created using (a) a somatic hybrid cmm + haploid Solanum tuberosum (tbr) (cv. Superior, US variety from Wisconsin) as male and (b) seven cultivars native to Peru of the species S. tuberosum sbsp. andigenum (adg) as females. All plant materials were part of the USPG germplasm collection. Sexual seeds of each family were sent to Peru for evaluations under the natural conditions of the Andean highlands and Altiplano. The plants were assessed for their response to frost, and genotypes showing exceptional tolerance were selected. Plants were also evaluated for good tuber traits and yield. Initial planting involving ~2,500 seedlings in five locations resulted in selecting 58 genotypes with exceptional frost tolerance, good recovery capacity after frost, and good tuber traits. Over the years, evaluations continued and were expanded to replicated field trials in the harsher conditions of the Altiplano (Puno). All trials confirmed consistency of frost tolerance over time and location, tuber quality, and yield. After 8 years, two advanced clones were considered for cultivar release because of their exceptional frost tolerance and superior field productivity that outyielded many of the established cultivars in the region. In November 2018, a new native cultivar named Wiñay, a Quechua word meaning "to grow" was released in Peru. In 2022, a second cultivar followed with the name Llapanchispaq (meaning "for all of us"). This project evidenced that a multinational and all-encompassing approach to deploy valuable genetic diversity can work and deliver effective results. This is even more significant when outcomes can promote food security and sustainability in very vulnerable regions of the world.

Comparative and phylogenetic analyses of the chloroplast genomes of Filipendula species (Rosoideae, Rosaceae)

Genus Filipendula (Rosoideae, Rosaceae) comprises about 15 species and mainly distributed in Northern Hemisphere. The phylogenetic relationships based on the nrITS marker are not consistent with the traditional taxonomic systems of the genus. Here, we first analysed the complete chloroplast (cp) genomes of seven Filipendula species (including two varieties of F. palmate). Our results indicated that the cp genomes of Filipendula species had few changes in size, ranging from 154,205 bp to 154,633 bp and the average of 36.63% GC content. A total of 126 annotated genes had the identical order and orientation, implying that the cp genome structure of Filipendula species was rather conserved. However, the cp genomes of Filipendula species exhibited structural differences, including gene loss, transposition and inversion when compared to those of other genera of Rosoideae. Moreover, SSRs with the different number were observed in the cp genome of each Filipendula species and sequence divergence mainly occurred in noncoding regions, in which four mutational hotspots were identified. In contrast, only two positive selection genes (matK and rps8) were found. Phylogenetic and molecular-dating analysis indicated that Filipendula species were divergent from other genera of Rosoideae at about 82.88 Ma. Additionally, Filipendula species from East Asia were split at about 9.64 Ma into two major clades. These results provide a basis for further studying the infrageneric classification of Filipendula.

Complete chloroplast genome sequence of Camellia sinensis: genome structure, adaptive evolution, and phylogenetic relationships

The chloroplast (cp) genome holds immense potential for a variety of applications including species identification, phylogenetic analysis, and evolutionary studies. In this study, we utilized Illumina NovaSeq 6000 to sequence the DNA of Camellia sinensis L. cultivar 'Zhuyeqi', followed by the assembly of its chloroplast genome using SPAdes v3.10.1, with subsequent analysis of its features and phylogenetic placement. The results showed that the cp genome of 'Zhuyeqi' was 157,072 bp, with a large single-copy region (LSC, 86,628 bp), a small single-copy region (SSC,18,282 bp), and two inverted repeat regions (IR, 26,081 bp). The total AT and GC contents of the cp genome of 'Zhuyeqi' were observed to be 62.21% and 37.29%, respectively. The cp genome encoded 135 unique genes, including 90 protein-coding genes (CDS), 37 tRNA genes, and 8 rRNA genes. Moreover, 31 codons and 247 simple sequence repeats (SSRs) were identified. The cp genomes of 'Zhuyeqi' were found to be relatively conserved, with conservation observed in the IR region, which showed no evidence of inversions or rearrangements. The five regions with the largest variations were identified, with four regions (rps12, rps19, rps16, and rpl33) located in the LSC region and one divergent region (trnI-GAU) in the IR region. Phylogenetic analysis revealed that Camellia sinensis (KJ996106.1) was closely related to 'Zhuyeqi', indicating a close phylogenetic relationship between these two species. These findings could provide important genetic information for further research into breeding of tea tree, phylogeny, and evolution of Camellia sinensis.

Analysis of the Chloroplast Genome of Ficus simplicissima Lour Collected in Vietnam and Proposed Barcodes for Identifying Ficus Plants

Ficus simplicissima Lour. is an Asian species of fig tree in the family Moraceae. The chloroplast (cp) genome of F. simplicissima m3 was sequenced using the Pacbio sequel platform. The F. simplicissima cpDNA has a size of 160,321 bp in length, of which GC content accounts for 36.13%. The cp genome of F. simplicissima consists of a single large copy (LSC) with a size of 91,346 bp, a single small copy (SSC) with a size of 20,131 bp, and a pair of inverted repeats with a size of 24,421 to 24,423 bp. The cp genome of F. simplicissima has 127 genes, including 85 protein-coding genes, eight rRNA genes, and 34 tRNA genes; 92 simple sequence repeats and 39 long repeats were detected in the cpDNA of F. simplicissim. A comparative cp genome analysis among six species in the Ficus genus indicated that the genome structure and gene content were highly conserved. The non-coding regions show more differentiation than the coding regions, and the LSC and SSC regions show more differences than the inverted repeat regions. Phylogenetic analysis supported that F. simplicissima m3 had a close relationship with F. hirta. The complete cp genome of F. simplicissima was proposed as a chloroplast DNA barcoding for genus-level in the Moraceae family and the psbA-trnH gene region for species-level identification.

Complete chloroplast genome sequence of Solanum iopetalum, one of the tuber-bearing wild potato relatives

Solanum iopetalum belongs to the Solanaceae family and is one of the tuber-bearing wild Solanum species. In this study, chloroplast genome sequencing of the species, completed with Illumina sequencing technology, is presented. The length of the chloroplast genome is 155,625 bp with a GC content of 37.86%. It comprises a large single copy (LSC) region of 86,057 bp, a small single copy (SSC) region of 18,382 bp, and two inverted repeat regions (IRa and IRb) of 25,593 bp. Additionally, 158 functional genes in the genome are identified, including 105 protein-coding genes, 8 ribosomal RNAs, and 45 transfer RNAs. Phylogenetic analysis revealed that S. iopetalum is grouped into a large clade with other Solanum species, including cultivated potatoes (S. tuberosum) and is closely related to Mexican Solanum species (S. stoloniferum, S. verrucosum, S. hougasii, S. hjertingii, and S. demissum). This study provides useful genomic information for future breeding and evolutionary studies of S. iopetalum and other Solanum species.

Molecular Structure and Phylogenetic Analyses of the Plastomes of Eight Sorbus Sensu Stricto Species

Sorbus L. is a genus of controversy on its taxonomic concept due to great variations in morphological characteristics. Sorbus sensu stricto species, being monophyletic, are characterized as pinnate leaves. However, phylogenetic relationships of these species are somewhat fluid based on morphological characteristics and genetic markers. In this study, the chloroplast (cp) genomes of eight Sorbus s. str. species were characterized and compared with those of twelve released species in this genus. Our results indicated that the plastomes of the twenty Sorbus species had a conserved quadripartite structure, and 129 annotated genes had the same order and showed a good collinearity. Additionally, numerous SSRs were observed in the cp genome of each Sorbus species; most of the sequence variations appeared in non-coding regions, and four intergenic regions were identified as mutation spots. By contrast, protein-coding genes showed low variations under purifying selection. The phylogenetic and molecular-dating analysis showed that Sorbus was resolved into two major clades, in which S. americana forms one clade originating at 51.78 Ma, and the rest of Sorbus formed another clade, splitting at 36.77 Ma into two sister groups with high support values. These results provide a basis for further studying the phylogenetic relationship and biogeography of Sorbus species.

Mitochondrial genome recombination in somatic hybrids of Solanum commersonii and S. tuberosum

Interspecific somatic hybridization has been performed in potato breeding experiments to increase plant resistance against biotic and abiotic stress conditions. We analyzed the mitochondrial and plastid genomes and 45S nuclear ribosomal DNA (45S rDNA) for the cultivated potato (S. tuberosum, St), wild potato (S. commersonii, Sc), and their somatic hybrid (StSc). Complex genome components and structure, such as the hybrid form of 45S rDNA in StSc, unique plastome in Sc, and recombinant mitogenome were identified. However, the mitogenome exhibited dynamic multipartite structures in both species as well as in the somatic hybrid. In St, the mitogenome is 756,058 bp and is composed of five subgenomes ranging from 297,014 to 49,171 bp. In Sc, it is 552,103 bp long and is composed of two sub-genomes of 338,427 and 213,676 bp length. StSc has 447,645 bp long mitogenome with two subgenomes of length 398,439 and 49,206 bp. The mitogenome structure exhibited dynamic recombination mediated by tandem repeats; however, it contained highly conserved genes in the three species. Among the 35 protein-coding genes of the StSc mitogenome, 21 were identical for all the three species, and 12 and 2 were unique in Sc and St, respectively. The recombinant mitogenome might be derived from homologous recombination between both species during somatic hybrid development.

Uncovering the first complete plastome genomics, comparative analyses, and phylogenetic dispositions of endemic medicinal plant Ziziphus hajarensis (Rhamnaceae)

BACKGROUND

Ziziphus hajarensis is an endemic plant species well-distributed in the Western Hajar mountains of Oman. Despite its potential medicinal uses, little is known regarding its genomic architecture, phylogenetic position, or evolution. Here we sequenced and analyzed the entire chloroplast (cp) genome of Z. hajarensis to understand its genetic organization, structure, and phylogenomic disposition among Rhamnaceae species.

RESULTS

The results revealed the genome of Z. hajarensis cp comprised 162,162 bp and exhibited a typical quadripartite structure, with a large single copy (LSC) region of 895,67 bp, a small single copy (SSC) region of 19,597 bp and an inverted repeat (IR) regions of 26,499 bp. In addition, the cp genome of Z. hajarensis comprises 126 genes, including 82 protein-coding genes, eight rRNA genes, and 36 tRNA genes. Furthermore, the analysis revealed 208 microsatellites, 96.6% of which were mononucleotides. Similarly, a total of 140 repeats were identified, including 11 palindromic, 24 forward, 14 reverse, and 104 tandem repeats. The whole cp genome comparison of Z. hajarensis and nine other species from family Rhamnaceae showed an overall high degree of sequence similarity, with divergence among some intergenic spacers. Comparative phylogenetic analysis based on the complete cp genome, 66 shared genes and matK gene revealed that Z. hajarensis shares a clade with Z. jujuba and that the family Rhamnaceae is the closest family to Barbeyaceae and Elaeagnaceae.

CONCLUSION

All the genome features such as genome size, GC content, genome organization and gene order were highly conserved compared to the other related genomes. The whole cp genome of Z. hajarensis gives fascinating insights and valuable data that may be used to identify related species and reconstruct the phylogeny of the species.

Effect of Inoculation with Arbuscular Mycorrhizal Fungi and Fungicide Application on the Secondary Metabolism of Solanum tuberosum Leaves

In potato (Solanum tuberosum) crops, the use of fungicides to control some diseases is widespread; however, it has been reported that this practice can modify the potato polyphenolic content, and new strategies oriented to the potato defense system are necessary. One alternative is the use of arbuscular mycorrhizal fungi (AMF) to improve the defense mechanisms of plants. In this study, phenolic profiles and antioxidant activities in leaves of three potato genotypes (CB2011-509, CB2011-104, and VR808) were evaluated in crops inoculated with three AMF strains (Claroideoglomus claroideum, Claroideoglomus lamellosum, and Fumneliformis mosseae) and with AMF in combination with the use of two commercial fungicides (MONCUT [M] and ReflectXtra [R]). Eight phenolic compounds were detected, mainly hydroxycinnamic acids (HCAD) and flavonols, in samples where the highest concentrations of HCAD were obtained, 5-caffeoylquinic acid was the most abundant phenolic. The antioxidant activity was higher using the cupric reducing antioxidant capacity (CUPRAC) and ferric reducing antioxidant power (FRAP) methods. The association of AMF with plants had benefits on the secondary metabolism; however, the response differed according to genotype. The different combinations of potato genotypes, AMF strain, and fungicide modified the content of phenolic compounds in leaves in different ways; the treatment using C. lamellosum and ReflectXtra was the ideal combination for the genotypes analyzed here, with the higher antioxidant response, which supports the further technological evaluation of efficient AMF strains and fungicides in potato crops.

Complete plastome assemblies from a panel of 13 diverse potato taxa

The chloroplasts are a crucial part of photosynthesizing plant cells and are extensively utilized in phylogenetic studies mainly due to their maternal inheritance. Characterization and analysis of complete plastome sequences is necessary to understand their diversity and evolutionary relationships. Here, a panel of thirteen plastomes from various potato taxa are presented. Though they are highly similar with respect to gene order and content, there is also a great extent of SNPs and InDels between them, with one of the Solanum bukasovii plastomes (BUK2) having the highest number of SNPs and InDels. Five different potato plastome types (C, S, A, W, W2) are present in the panel. Interestingly, the S. tuberosum subsp. tuberosum (TBR) accession has a W-type plastome, which is not commonly found in this species. The S-type plastome has a conserved 48 bp deletion not found in other types, which is responsible for the divergence of the S-type from the C-type plastome. Finally, a phylogenetic analysis shows that these plastomes cluster according to their types. Congruence between the nuclear genome and the plastome phylogeny of these accessions was seen, however with considerable differences, supporting the hypothesis of introgression and hybridization between potato species.

Unraveling the Chloroplast Genomes of Two Prosopis Species to Identify Its Genomic Information, Comparative Analyses and Phylogenetic Relationship

Genus Prosopis (family Fabaceae) are shrubby trees, native to arid and semi-arid regions of Asia, Africa, and America and known for nitrogen fixation. Here, we have sequenced the complete chloroplast (cp) genomes of two Prosopis species (P. juliflora and P. cineraria) and compared them with previously sequenced P. glandulosa, Adenanthera microsperma, and Parkia javanica belonging to the same family. The complete genome sequences of Prosopis species and related species ranged from 159,389 bp (A. microsperma) to 163,677 bp (P. cineraria). The overall GC contents of the genomes were almost the similar (35.9–36.6%). The P. juliflora and P. cineraria genomes encoded 132 and 131 genes, respectively, whereas both the species comprised of 85 protein-coding genes higher than other compared species. About 140, 134, and 129 repeats were identified in P. juliflora, P. cineraria and P. glandulosa cp genomes, respectively. Similarly, the maximum number of simple sequence repeats were determined in P. juliflora (88), P. cineraria (84), and P. glandulosa (78). Moreover, complete cp genome comparison determined a high degree of sequence similarity among P. juliflora, P. cineraria, and P. glandulosa, however some divergence in the intergenic spacers of A. microsperma and Parkia javanica were observed. The phylogenetic analysis showed that P. juliflora is closer to P. cineraria than P. glandulosa.

Deep-sequencing of Solanum commersonii small RNA libraries reveals riboregulators involved in cold stress response

Among wild species used in potato breeding, Solanum commersonii displays the highest tolerance to low temperatures under both acclimated (ACC) and non-acclimated (NACC) conditions. It is also the first wild potato relative with a known whole genome sequence. Recent studies have shown that abiotic stresses induce changes in the expression of many small non-coding RNA (sncRNA). We determined the small non-coding RNA (sncRNAome) of two clones of S. commersonii contrasting in their cold response phenotypes via smRNAseq. Differential analysis provided evidence that expression of several miRNAs changed in response to cold stress conditions. Conserved miR408a and miR408b changed their expression under NACC conditions, whereas miR156 and miR169 were differentially expressed only under ACC conditions. We also report changes in tasiRNA and secondary siRNA expression under both stress conditions. Our results reveal possible roles of sncRNA in the regulatory networks associated with tolerance to low temperatures and provide useful information for a more strategic use of genomic resources in potato breeding.

Characterization of the Complete Chloroplast Genome of Acer truncatum Bunge (Sapindales: Aceraceae): A New Woody Oil Tree Species Producing Nervonic Acid

Acer truncatum, which is a new woody oil tree species, is an important ornamental and medicinal plant in China. To assess the genetic diversity and relationships of A. truncatum, we analyzed its complete chloroplast (cp) genome sequence. The A. truncatum cp genome comprises 156,492 bp, with the large single-copy, small single-copy, and inverted repeat (IR) regions consisting of 86,010, 18,050, and 26,216 bp, respectively. The A. truncatum cp genome contains 112 unique functional genes (i.e., 4 rRNA, 30 tRNA, and 78 protein-coding genes) as well as 78 simple sequence repeats, 9 forward repeats, 1 reverse repeat, 5 palindromic repeats, and 7 tandem repeats. We analyzed the expansion/contraction of the IR regions in the cp genomes of six Acer species. A comparison of these cp genomes indicated the noncoding regions were more diverse than the coding regions. A phylogenetic analysis revealed that A. truncatum is closely related to A. miaotaiense. Moreover, a novel ycf4-cemA indel marker was developed for distinguishing several Acer species (i.e., A. buergerianum, A. truncatum, A. henryi, A. negundo, A. ginnala, and A. tonkinense). The results of the current study provide valuable information for future evolutionary studies and the molecular barcoding of Acer species.

Complete chloroplast genomes of medicinally important Teucrium species and comparative analyses with related species from Lamiaceae

Teucrium is one of the most economically and ecologically important genera in the Lamiaceae family; however, it is currently the least well understood at the plastome level. In the current study, we sequenced the complete chloroplast (cp) genomes of T. stocksianum subsp. stenophyllum R.A.King (TSS), T. stocksianum subsp. stocksianum Boiss. (TS) and T. mascatense Boiss. (TM) through next-generation sequencing and compared them with the cp genomes of related species in Lamiaceae (Ajuga reptans L., Caryopteris mongholica Bunge, Lamium album L., Lamium galeobdolon (L.) Crantz, and Stachys byzantina K.Koch). The results revealed that the TSS, TS and TM cp genomes have sizes of 150,087, 150,076 and 150,499 bp, respectively. Similarly, the large single-copy (LSC) regions of TSS, TS and TM had sizes of 81,707, 81,682 and 82,075 bp, respectively. The gene contents and orders of these genomes were similar to those of other angiosperm species. However, various differences were observed at the inverted repeat (IR) junctions, and the extent of the IR expansion into ψrps19 was 58 bp, 23 bp and 61 bp in TSS, TS and TM, respectively. Similarly, in all genomes, the pbsA gene was present in the LSC at varying distances from the JLA (IRa-LSC) junction. Furthermore, 89, 72, and 92 repeats were identified in the TSS, TM and TS cp genomes, respectively. The highest number of simple sequence repeats was found in TSS (128), followed by TS (127) and TM (121). Pairwise alignments of the TSS cp genome with related cp genomes showed a high degree of synteny. However, relatively lower sequence identity was observed when various coding regions were compared to those of related cp genomes. The average pairwise divergence among the complete cp genomes showed that TSS was more divergent from TM (0.018) than from TS (0.006). The current study provides valuable genomic insight into the genus Teucrium and its subspecies that may be applied to a more comprehensive study.

Sequencing and Structural Analysis of the Complete Chloroplast Genome of the Medicinal Plant Lycium chinense Mill

Lycium chinense Mill, an important Chinese herbal medicine, is widely used as a dietary supplement and food. Here the chloroplast (CP) genome of L. chinense was sequenced and analyzed, revealing a size of 155,756 bp and with a 37.8% GC content. The L. chinense CP genome comprises a large single copy region (LSC) of 86,595 bp and a small single copy region (SSC) of 18,209 bp, and two inverted repeat regions (IRa and IRb) of 25,476 bp separated by the single copy regions. The genome encodes 114 genes, 16 of which are duplicated. Most of the 85 protein-coding genes (CDS) had standard ATG start codons, while 3 genes including rps12, psbL and ndhD had abnormal start codons (ACT and ACG). In addition, a strong A/T bias was found in the majority of simple sequence repeats (SSRs) detected in the CP genome. Analysis of the phylogenetic relationships among 16 species revealed that L. chinense is a sister taxon to Lycium barbarum. Overall, the complete sequence and annotation of the L. chinense CP genome provides valuable genetic information to facilitate precise understanding of the taxonomy, species and phylogenetic evolution of the Solanaceae family.

Differences in Codon Usage Bias between Photosynthesis-Related Genes and Genetic System-Related Genes of Chloroplast Genomes in Cultivated and Wild Solanum Species

Solanum is one of the largest genera, including two important crops-potato (Solanum tuberosum) and tomato (Solanum lycopersicum). In this study we compared the chloroplast codon usage bias (CUB) among 12 Solanum species, between photosynthesis-related genes (Photo-genes) and genetic system-related genes (Genet-genes), and between cultivated species and wild relatives. The Photo-genes encode proteins for photosystems, the photosynthetic electron transport chain, and RuBisCO, while the Genet-genes encode proteins for ribosomal subunits, RNA polymerases, and maturases. The following findings about the Solanum chloroplast genome CUB were obtained: (1) the nucleotide composition, gene expression, and selective pressure are identified as the main factors affecting chloroplast CUB; (2) all these 12 chloroplast genomes prefer A/U over G/C and pyrimidines over purines at the third-base of codons; (3) Photo-genes have higher codon adaptation indexes than Genet-genes, indicative of a higher gene expression level and a stronger adaptation of Photo-genes; (4) gene function is the primary factor affecting CUB of Photo-genes but not Genet-genes; (5) Photo-genes prefer pyrimidine over purine, whereas Genet-genes favor purine over pyrimidine, at the third position of codons; (6) Photo-genes are mainly affected by the selective pressure, whereas Genet-genes are under the underlying mutational bias; (7) S. tuberosum is more similar with Solanum commersonii than with Solanum bulbocastanum; (8) S. lycopersicum is greatly different from the analyzed seven wild relatives; (9) the CUB in codons for valine, aspartic acid, and threonine are the same between the two crop species, S. tuberosum and S. lycopersicum. These findings suggest that the chloroplast CUB contributed to the differential requirement of gene expression activity and function between Photo-genes and Genet-genes and to the performance of cultivated potato and tomato.

The complete plastid genomes of Ophrys iricolor and O. sphegodes (Orchidaceae) and comparative analyses with other orchids

Sexually deceptive orchids of the genus Ophrys may rapidly evolve by adaptation to pollinators. However, understanding of the genetic basis of potential changes and patterns of relationships is hampered by a lack of genomic information. We report the complete plastid genome sequences of Ophrys iricolor and O. sphegodes, representing the two most species-rich lineages of the genus Ophrys. Both plastomes are circular DNA molecules (146754 bp for O. sphegodes and 150177 bp for O. iricolor) with the typical quadripartite structure of plastid genomes and within the average size of photosynthetic orchids. 213 Simple Sequence Repeats (SSRs) (31.5% polymorphic between O. iricolor and O. sphegodes) were identified, with homopolymers and dipolymers as the most common repeat types. SSRs were mainly located in intergenic regions but SSRs located in coding regions were also found, mainly in ycf1 and rpoC2 genes. The Ophrys plastome is predicted to encode 107 distinct genes, 17 of which are completely duplicated in the Inverted Repeat regions. 83 and 87 putative RNA editing sites were detected in 25 plastid genes of the two Ophrys species, all occurring in the first or second codon position. Comparing the rate of nonsynonymous (dN) and synonymous (dS) substitutions, 24 genes (including rbcL and ycf1) display signature consistent with positive selection. When compared with other members of the orchid family, the Ophrys plastome has a complete set of 11 functional ndh plastid genes, with the exception of O. sphegodes that has a truncated ndhF gene. Comparative analysis showed a large co-linearity with other related Orchidinae. However, in contrast to O. iricolor and other Orchidinae, O. sphegodes has a shift of the junction between the Inverted Repeat and Small Single Copy regions associated with the loss of the partial duplicated gene ycf1 and the truncation of the ndhF gene. Data on relative genomic coverage and validation by PCR indicate the presence, with a different ratio, of the two plastome types (i.e. with and without ndhF deletion) in both Ophrys species, with a predominance of the deleted type in O. sphegodes. A search for this deleted plastid region in O. sphegodes nuclear genome shows that the deleted region is inserted in a retrotransposon nuclear sequence. The present study provides useful genomic tools for studying conservation and patterns of relationships of this rapidly radiating orchid genus.

Organellar genome analysis reveals endosymbiotic gene transfers in tomato

We assembled three complete mitochondrial genomes (mitogenomes), two of Solanum lycopersicum and one of Solanum pennellii, and analyzed their intra- and interspecific variations. The mitogenomes were 423,596-446,257 bp in length. Despite numerous rearrangements between the S. lycopersicum and S. pennellii mitogenomes, over 97% of the mitogenomes were similar to each other. These mitogenomes were compared with plastid and nuclear genomes to investigate genetic material transfers among DNA-containing organelles in tomato. In all mitogenomes, 9,598 bp of plastome sequences were found. Numerous nuclear copies of mitochondrial DNA (NUMTs) and plastid DNA (NUPTs) were observed in the S. lycopersicum and S. pennellii nuclear genomes. Several long organellar DNA fragments were tightly clustered in the nuclear genome; however, the NUMT and NUPT locations differed between the two species. Our results demonstrate the recent occurrence of frequent endosymbiotic gene transfers in tomato genomes.

The complete chloroplast genome sequence of Solanum hougasii, one of the potato wild relative species

Solanum hougasii is a wild tuber-bearing species belonging to the family Solanaceae. The complete chloroplast genome of S. hougasii was constituted by de novo assembly, using a small amount of whole genome sequencing data. The chloroplast genome of S. hougasii was a circular DNA molecule with a length of 155,549 bp and consisted of 85,990 bp of large single copy, 18,373 bp of small single copy, and 25,593 bp of a pair of inverted repeat regions. A total of 158 genes were annotated, including 105 protein-coding genes, 45 tRNA genes, and eight rRNA genes. Maximum likelihood phylogenetic analysis with 25 Solanaceae species revealed that S. hougasii is most closely grouped with S. tuberosum.

Mitochondrial genome sequence of tuber-bearing wild potato, Solanum commersonii Dunal

We report two complete mitochondrial genome sequences of a tuber-bearing wild potato species (Solanum commersonii). The genomes are circular DNA molecules with lengths of 213,676 bp and 338,427 bp containing 80 nonredundant genes totally, including 34 protein-coding genes, 25 hypothetical open reading frames, 18 tRNA genes, and 3 rRNA genes. Phylogenetic analysis using common protein-coding sequences confirmed that S. commersonii belongs to the Solanoideae subfamily in the Solanaceae family.

Chloroplast genome sequence of the wild tetraploid potato relativeSolanum stoloniferum

Solanum stoloniferum is a wild tuber-bearing species belonging to Solanaceae family. The complete chloroplast genome of S. stoloniferum was constituted by de novo assembly using a small amount of whole genome sequencing data. The chloroplast genome of S. stoloniferum was the circular DNA molecule with a length of 155,567 bp and consisted of 86,007 bp of large single copy, 18,374 bp of small single copy, and 25,593 bp of a pair of inverted repeat regions. A total of 158 genes were annotated including 105 protein-coding genes, 45 tRNA genes, and eight rRNA genes. Maximum likelihood phylogenetic analysis with 25 Solanaceae species revealed that S. stoloniferum is the most closely grouped with S. tuberosum.

Chloroplast genome of the wild tuber-bearing diploid potato relative Solanum chacoense

Solanum chacoense is a wild tuber-bearing species belonging to Solanaceae family. The chloroplast genome of the species was completed by de novo assembly using a small amount of whole genome sequencing data. The genome is the circular DNA molecule with a length of 155,532 bp containing 159 predicted genes totally, including 105 protein-coding, 45 tRNA and eight rRNA genes. Maximum-likelihood phylogenetic analysis with 26 species in Solanaceae revealed that S. chacoense is the most closely grouped with S. commersonii.

The Complete Chloroplast Genome Sequences of Aconitum pseudolaeve and Aconitum longecassidatum, and Development of Molecular Markers for Distinguishing Species in the Aconitum Subgenus Lycoctonum

Aconitum pseudolaeve Nakai and Aconitum longecassidatum Nakai, which belong to the Aconitum subgenus Lycoctonum, are distributed in East Asia and Korea. Aconitum species are used in herbal medicine and contain highly toxic components, including aconitine. A. pseudolaeve, an endemic species of Korea, is a commercially valuable material that has been used in the manufacture of cosmetics and perfumes. Although Aconitum species are important plant resources, they have not been extensively studied, and genomic information is limited. Within the subgenus Lycoctonum, which includes A. pseudolaeve and A. longecassidatum, a complete chloroplast (CP) genome is available for only one species, Aconitum barbatum Patrin ex Pers. Therefore, we sequenced the complete CP genomes of two Aconitum species, A. pseudolaeve and A. longecassidatum, which are 155,628 and 155,524 bp in length, respectively. Both genomes have a quadripartite structure consisting of a pair of inverted repeated regions (51,854 and 52,108 bp, respectively) separated by large single-copy (86,683 and 86,466 bp) and small single-copy (17,091 and 16,950 bp) regions similar to those in other Aconitum CP genomes. Both CP genomes consist of 112 unique genes, 78 protein-coding genes, 4 ribosomal RNA (rRNA) genes, and 30 transfer RNA (tRNA) genes. We identified 268 and 277 simple sequence repeats (SSRs) in A. pseudolaeve and A. longecassidatum, respectively. We also identified potential 36 species-specific SSRs, 53 indels, and 62 single-nucleotide polymorphisms (SNPs) between the two CP genomes. Furthermore, a comparison of the three Aconitum CP genomes from the subgenus Lycoctonum revealed highly divergent regions, including trnK-trnQ, ycf1-ndhF, and ycf4-cemA. Based on this finding, we developed indel markers using indel sequences in trnK-trnQ and ycf1-ndhF. A. pseudolaeve, A. longecassidatum, and A. barbatum could be clearly distinguished using the novel indel markers AcoTT (Aconitum trnK-trnQ) and AcoYN (Aconitum ycf1-ndhF). These two new complete CP genomes provide useful genomic information for species identification and evolutionary studies of the Aconitum subgenus Lycoctonum.

The complete chloroplast genome of Solanum berthaultii, one of the potato wild relative species

Solanum berthaultii is a wild species belonging to Solanaceae family. The complete chloroplast genome of S. berthaultii was constituted by de novo assembly using a small amount of whole genome sequencing data. The chloroplast genome of S. berthaultii was 155,533 bp in length and consisted of 25,593 bp of a pair of inverted repeats, 18,372 bp of small single copy and 85,975 bp of large single-copy regions. 158 genes were annotated including 105 protein-coding, 45 tRNA, and 8 rRNA genes. Maximum-likelihood phylogenetic analysis with eight Solanaceae species revealed that S. berthaultii is most closely grouped with S. tuberosum.

Complete Chloroplast Genome Sequences and Comparative Analysis of Chenopodium quinoa and C. album

The Chenopodium genus comprises ~150 species, including Chenopodium quinoa and Chenopodium album, two important crops with high nutritional value. To elucidate the phylogenetic relationship between the two species, the complete chloroplast (cp) genomes of these species were obtained by next generation sequencing. We performed comparative analysis of the sequences and, using InDel markers, inferred phylogeny and genetic diversity of the Chenopodium genus. The cp genome is 152,099 bp (C. quinoa) and 152,167 bp (C. album) long. In total, 119 genes (78 protein-coding, 37 tRNA, and 4 rRNA) were identified. We found 14 (C. quinoa) and 15 (C. album) tandem repeats (TRs); 14 TRs were present in both species and C. album and C. quinoa each had one species-specific TR. The trnI-GAU intron sequences contained one (C. quinoa) or two (C. album) copies of TRs (66 bp); the InDel marker was designed based on the copy number variation in TRs. Using the InDel markers, we detected this variation in the TR copy number in four species, Chenopodium hybridum, Chenopodium pumilio, Chenopodium ficifolium, and Chenopodium koraiense, but not in Chenopodium glaucum. A comparison of coding and non-coding regions between C. quinoa and C. album revealed divergent sites. Nucleotide diversity >0.025 was found in 17 regions-14 were located in the large single copy region (LSC), one in the inverted repeats, and two in the small single copy region (SSC). A phylogenetic analysis based on 59 protein-coding genes from 25 taxa resolved Chenopodioideae monophyletic and sister to Betoideae. The complete plastid genome sequences and molecular markers based on divergence hotspot regions in the two Chenopodium taxa will help to resolve the phylogenetic relationships of Chenopodium.