scholarly journals Plastome of the mycoheterotrophic eudicot Exacum paucisquama (Gentianaceae) exhibits extensive gene loss and a highly expanded inverted repeat region

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9157
Author(s):  
Zhanghai Li ◽  
Xiao Ma ◽  
Yi Wen ◽  
Sisi Chen ◽  
Yan Jiang ◽  
...  

Mycoheterotrophic plants are highly specialized species able to acquire organic carbon from symbiotic fungi, with relaxed dependence on photosynthesis for carbon fixation. The relaxation of the functional constraint of photosynthesis and thereby the relaxed selective pressure on functional photosynthetic genes usually lead to substantial gene loss and a highly degraded plastid genome in heterotrophs. In this study, we sequenced and analyzed the plastome of the eudicot Exacum paucisquama, providing the first plastid genome of a mycoheterotroph in the family Gentianaceae to date. The E. paucisquama plastome was 44,028 bp in length, which is much smaller than the plastomes of autotrophic eudicots. Although the E. paucisquama plastome had a quadripartite structure, a distinct boundary shift was observed in comparison with the plastomes of other eudicots. We detected extensive gene loss and only 21 putative functional genes (15 protein-coding genes, four rRNA genes and two tRNA genes). Our results provide valuable information for comparative evolutionary analyses of plastomes of heterotrophic species belonging to different phylogenetic groups.

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7830 ◽  
Author(s):  
Eugeny V. Gruzdev ◽  
Vitaly V. Kadnikov ◽  
Alexey V. Beletsky ◽  
Andrey V. Mardanov ◽  
Nikolai V. Ravin

Background Parasitic plants have the ability to obtain nutrients from their hosts and are less dependent on their own photosynthesis or completely lose this capacity. The reduction in plastid genome size and gene content in parasitic plants predominantly results from loss of photosynthetic genes. Plants from the family Orobanchaceae are used as models for studying plastid genome evolution in the transition from an autotrophic to parasitic lifestyle. Diphelypaea is a poorly studied genus of the Orobanchaceae, comprising two species of non-photosynthetic root holoparasites. In this study, we sequenced the plastid genome of Diphelypaea coccinea and compared it with other Orobanchaceae, to elucidate patterns of plastid genome evolution. In addition, we used plastid genome data to define the phylogenetic position of Diphelypaea spp. Methods The complete nucleotide sequence of the plastid genome of D. coccinea was obtained from total plant DNA, using pyrosequencing technology. Results The D. coccinea plastome is only 66,616 bp in length, and is highly rearranged; however, it retains a quadripartite structure. It contains only four rRNA genes, 25 tRNA genes and 25 protein-coding genes, being one of the most highly reduced plastomes among the parasitic Orobanchaceae. All genes related to photosynthesis, including the ATP synthase genes, had been lost, whereas most housekeeping genes remain intact. The plastome contains two divergent, but probably intact clpP genes. Intron loss had occurred in some protein-coding and tRNA genes. Phylogenetic analysis yielded a fully resolved tree for the Orobanchaceae, with Diphelypaea being a sister group to Orobanche sect. Orobanche.


2021 ◽  
Vol 104 (4) ◽  
pp. 003685042110599
Author(s):  
Dhafer Alzahrani ◽  
Enas Albokhari ◽  
Abidina Abba ◽  
Samaila Yaradua

Caylusea hexagyna and Ochradenus baccatus are two species in the Resedaceae family. In this study, we analysed the complete plastid genomes of these two species using high-throughput sequencing technology and compared their genomic data. The length of the plastid genome of C. hexagyna was 154,390 bp while that of O. baccatus was 153,380 bp. The lengths of the inverted repeats (IR) regions were 26,526 bp and 26,558 bp, those of the large single copy (LSC) regions were 83,870 bp and 83,023 bp; and those of the small single copy (SSC) regions were 17,468 bp and 17,241 bp in C. hexagyna and O. baccatus, respectively. Both genomes consisted of 113 genes: 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Repeat analysis showed that the plastid genome included all types of repeats, with more frequent occurrences of palindromic sequences. Comparative studies of SSR markers showed that there were 256 markers in C. hexagyna and 255 in O. baccatus; the majority of the SSRs in these plastid genomes were mononucleotide repeats (A/T). All the clusters in the phylogenetic tree had high support. This study reported the first complete plastid genomes of the genera Caylusea and Ochradenus and the first for the Resedaceae family.


Author(s):  
Sangjin Jo ◽  
Ki-Joong Kim

Croton L. (Euphorbiaceae) is a very specious genus and consists of about 1,250 species, mainly distributed in tropical Asia and China. The first complete plastome sequence from the genus, Croton tiglium, is reported in this study (NCBI acc. No. MH394334). The plastome is 150,021 bp in length. The lengths of LSC and SSC are 111,654 bp and 18,167 bp, respectively. However, the length of the IR region is only 10,100 bp and includes only four rrn and four trn genes, and a small part of the ycf1 gene. We propose two-step IR contractions to explain this unique IR region of the C. tiglium plastome. First, the IR contracted from rps19-rpl2 to ycf2-trnL-CAA on the LSC/IRb boundary. Second, the IR contracted from ycf2-trnL-CAA to rrn16-trnV-GAC on the LSC/IRa boundary. In addition, duplicated copies of psaI genes were discovered in the C. tiglium plastome. Both copies were located side by side between accD and ycf4 genes, but one copy was pseudogenized because of a five-basepair (TAGCT) insertion in the middle of the gene following frameshift mutation. The plastome contains 112 genes, of which 78 are protein-coding genes, 30 are tRNA genes, and four are rRNA genes. Sixteen genes contain one intron and two genes have two introns. The infA gene is lost. Twelve large repeats were detected in the plastome. All large repeats are located in the LSC region. Also, 272 simple sequence repeats (SSRs) were identified. The penta-SSRs accounted for 45% of total SSRs, followed by mono- (32%), di- (12%), tetra (6%) and tri-SSRs (5%). Most of them were distributed in the large single copy (LSC) region (85%). In addition, 76% of the SSRs were located in the intergenic spacer (IGS). Phylogenetic analysis suggested that C. tiglium is a sister group of Jatropha curcas with 100% bootstrap support. Seven Euphorbiaceae species formed one clade with 100% bootstrap support.


2021 ◽  
Author(s):  
Mahtab Moghaddam ◽  
Atsushi Ohta ◽  
Motoki Shimizu ◽  
Ryohei Terauchi ◽  
Shahrokh Kazempour-Osaloo

Abstract Plastid genome sequences provide valuable markers for surveying the evolutionary relationships and population genetics of plant species. In the present study, the complete plastid genome of Onobrychis gaubae, endemic to Iran, was sequenced using Illumina paired-end sequencing and was compared with previously known genomes of the IRLC species of legumes. The O. gaubae plastid genome was 123,645 bp in length and included a large single-copy (LSC) region of 81,034 bp, a small single-copy (SSC) region of 13,788 bp and one copy of the inverted repeat (IRb) of 28,823 bp. The genome encoded 110 genes, including 76 protein-coding genes, 30 transfer RNA (tRNA) genes and four ribosome RNA (rRNA) genes and possessed 89 simple sequence repeats (SSRs) and 28 repeated structures with the highest proportion in the LSC. Comparative analysis of the chloroplast genomes across IRLC revealed three hotspot genes (ycf1, ycf2, clpP) which could be used as molecular markers for resolving phylogenetic relationships and species identification. IRLC plastid genomes also showed multiple gene losses and inversions. Phylogenetic analyses revealed that O. gaubae is closely related to Hedysarum. The complete O. gaubae genome is a valuable resource for investigating evolution of Onobrychis species and can be used to identify related species.


Author(s):  
Sangjin Jo ◽  
Ki-Joong Kim

Croton L. (Euphorbiaceae) is a very specious genus and consists of about 1,250 species, mainly distributed in tropical Asia and China. The first complete plastome sequence from the genus, Croton tiglium, is reported in this study (NCBI acc. No. MH394334). The plastome is 150,021 bp in length. The lengths of LSC and SSC are 111,654 bp and 18,167 bp, respectively. However, the length of the IR region is only 10,100 bp and includes only four rrn and four trn genes, and a small part of the ycf1 gene. We propose two-step IR contractions to explain this unique IR region of the C. tiglium plastome. First, the IR contracted from rps19-rpl2 to ycf2-trnL-CAA on the LSC/IRb boundary. Second, the IR contracted from ycf2-trnL-CAA to rrn16-trnV-GAC on the LSC/IRa boundary. In addition, duplicated copies of psaI genes were discovered in the C. tiglium plastome. Both copies were located side by side between accD and ycf4 genes, but one copy was pseudogenized because of a five-basepair (TAGCT) insertion in the middle of the gene following frameshift mutation. The plastome contains 112 genes, of which 78 are protein-coding genes, 30 are tRNA genes, and four are rRNA genes. Sixteen genes contain one intron and two genes have two introns. The infA gene is lost. Twelve large repeats were detected in the plastome. All large repeats are located in the LSC region. Also, 272 simple sequence repeats (SSRs) were identified. The penta-SSRs accounted for 45% of total SSRs, followed by mono- (32%), di- (12%), tetra (6%) and tri-SSRs (5%). Most of them were distributed in the large single copy (LSC) region (85%). In addition, 76% of the SSRs were located in the intergenic spacer (IGS). Phylogenetic analysis suggested that C. tiglium is a sister group of Jatropha curcas with 100% bootstrap support. Seven Euphorbiaceae species formed one clade with 100% bootstrap support.


Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1517
Author(s):  
Se-Hwan Cheon ◽  
Min-Ah Woo ◽  
Sangjin Jo ◽  
Young-Kee Kim ◽  
Ki-Joong Kim

The genus Zoysia Willd. (Chloridoideae) is widely distributed from the temperate regions of Northeast Asia—including China, Japan, and Korea—to the tropical regions of Southeast Asia. Among these, four species—Zoysia japonica Steud., Zoysia sinica Hance, Zoysia tenuifolia Thiele, and Zoysia macrostachya Franch. & Sav.—are naturally distributed in the Korean Peninsula. In this study, we report the complete plastome sequences of these Korean Zoysia species (NCBI acc. nos. MF953592, MF967579~MF967581). The length of Zoysia plastomes ranges from 135,854 to 135,904 bp, and the plastomes have a typical quadripartite structure, which consists of a pair of inverted repeat regions (20,962~20,966 bp) separated by a large (81,348~81,392 bp) and a small (12,582~12,586 bp) single-copy region. In terms of gene order and structure, Zoysia plastomes are similar to the typical plastomes of Poaceae. The plastomes encode 110 genes, of which 76 are protein-coding genes, 30 are tRNA genes, and four are rRNA genes. Fourteen genes contain single introns and one gene has two introns. Three evolutionary hotspot spacer regions—atpB~rbcL, rps16~rps3, and rpl32~trnL-UAG—were recognized among six analyzed Zoysia species. The high divergences in the atpB~rbcL spacer and rpl16~rpl3 region are primarily due to the differences in base substitutions and indels. In contrast, the high divergence between rpl32~trnL-UAG spacers is due to a small inversion with a pair of 22 bp stem and an 11 bp loop. Simple sequence repeats (SSRs) were identified in 59 different locations in Z. japonica, 63 in Z. sinica, 62 in Z. macrostachya, and 63 in Z. tenuifolia plastomes. Phylogenetic analysis showed that the Zoysia (Zoysiinae) forms a monophyletic group, which is sister to Sporobolus (Sporobolinae), with 100% bootstrap support. Within the Zoysia clade, the relationship of (Z. sinica, Z japonica), (Z. tenuifolia, Z. matrella), (Z. macrostachya, Z. macrantha) was suggested.


2019 ◽  
Vol 8 (37) ◽  
Author(s):  
Gareth T. Little ◽  
Muhammad Ehsaan ◽  
Christian Arenas-López ◽  
Kamran Jawed ◽  
Klaus Winzer ◽  
...  

The hydrogen-utilizing strain Cupriavidus necator H16 (DSM 428) was sequenced using a combination of PacBio and Illumina sequencing. Annotation of this strain reveals 6,543 protein-coding genes, 263 pseudogenes, 64 tRNA genes, and 15 rRNA genes.


2018 ◽  
Vol 94 ◽  
Author(s):  
P. Zhang ◽  
R.K. Ran ◽  
A.Y. Abdullahi ◽  
X.L. Shi ◽  
Y. Huang ◽  
...  

AbstractDipetalonema gracile is a common parasite in squirrel monkeys (Saimiri sciureus), which can cause malnutrition and progressive wasting of the host, and lead to death in the case of massive infection. This study aimed to identify a suspected D. gracile worm from a dead squirrel monkey by means of molecular biology, and to amplify its complete mitochondrial genome by polymerase chain reaction (PCR) and sequence analysis. The results identified the worm as D. gracile, and the full length of its complete mitochondrial genome was 13,584 bp, which contained 22 tRNA genes, 12 protein-coding genes, two rRNA genes, one AT-rich region and one small non-coding region. The nucleotide composition included A (16.89%), G (20.19%), T (56.22%) and C (6.70%), among which A + T = 73.11%. The 12 protein-coding genes used TTG and ATT as start codons, and TAG and TAA as stop codons. Among the 22 tRNA genes, only trnS1AGN and trnS2UCN exhibited the TΨC-loop structure, while the other 20 tRNAs showed the TV-loop structure. The rrnL (986 bp) and rrnS (685 bp) genes were single-stranded and conserved in secondary structure. This study has enriched the mitochondrial gene database of Dipetalonema and laid a scientific basis for further study on classification, and genetic and evolutionary relationships of Dipetalonema nematodes.


2021 ◽  
Vol 10 (7) ◽  
Author(s):  
Kentaro Miyazaki ◽  
Hikaru Suenaga ◽  
Mamoru Oshiki ◽  
Shuichi Kawano ◽  
Toshikazu Fukushima

ABSTRACT A thiocyanate-degrading bacterium, Thiohalobacter sp. strain COW1, was isolated from activated sludge treating coke oven wastewater, and the complete genome sequence was determined. COW1 contained a single circular chromosome (3.23 Mb; G+C content, 63.4%) in which 2,788 protein-coding genes, 39 tRNA genes, and 3 rRNA genes were identified.


PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242541
Author(s):  
Lvpei Du ◽  
Shanya Cai ◽  
Jun Liu ◽  
Ruoyu Liu ◽  
Haibin Zhang

Phymorhynchus is a genus of deep-sea snails that are most distributed in hydrothermal vent or cold seep environments. In this study, we presented the complete mitochondrial genome of P. buccinoides, a cold seep snail from the South China Sea. It is the first mitochondrial genome of a cold seep member of the superfamily Conoidea. The mitochondrial genome is 15,764 bp in length, and contains 13 protein-coding genes (PCGs), 2 rRNA genes, and 22 tRNA genes. These genes are encoded on the positive strand, except for 8 tRNA genes that are encoded on the negative strand. The start codon ATG and 3 types of stop codons, TAA, TAG and the truncated termination codon T, are used in the 13 PCGs. All 13 PCGs in the 26 species of Conoidea share the same gene order, while several tRNA genes have been translocated. Phylogenetic analysis revealed that P. buccinoides clustered with Typhlosyrinx sp., Eubela sp., and Phymorhynchus sp., forming the Raphitomidae clade, with high support values. Positive selection analysis showed that a residue located in atp6 (18 S) was identified as the positively selected site with high posterior probabilities, suggesting potential adaption to the cold seep environment. Overall, our data will provide a useful resource on the evolutionary adaptation of cold seep snails for future studies.


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