Lycophyte transcriptomes reveal two whole-genome duplications in Lycopodiaceae:Insights into the polyploidization of Phlegmariurus

Lycophytes are an ancient clade of the non-flowering vascular plants with chromosome numbers that vary from tens to hundreds.They are an excellent study system for examining whole-genome duplications(WGDs),or polyploidization,in spore-dispersed vascular plants.However,a lack of genome sequence data limits the reliable detection of very ancient WGDs,small-scale duplications(SSDs),and recent WGDs.Here,we integrated phylogenomic analysis and the distribution of synonymous substitutions per synonymous sites(Ks)of the transcriptomes of 13 species of lycophytes to identify,locate,and date multiple WGDs in the lycophyte family Lycopodiaceae.Additionally,we examined the genus Phlegmariurus for signs of genetic discordance,which can provide valuable insight into the underlying causes of such conflict(e.g.,hybridization,incomplete lineage sorting,or horizontal gene transfer).We found strong evidence that two WGD events occurred along the phylogenetic backbone of Lycopodiaceae,with one occurring in the common ancestor of extant Phlegmariurus(Lycopodiaceae)approximately 22-23 million years ago(Mya)and the other occurring in the common ancestor of Lycopodiaceae around 206-214 Mya.Interestingly,we found significant genetic discordance in the genus Phlegmariurus,indicating that the genus has a complex evolutionary history.This study provides molecular evidence for multiple WGDs in Lycopodiaceae and offers phylogenetic clues to the evolutionary history of Lycopodiaceae.

Comparative genomic analyses reveal cis-regulatory divergence after polyploidization in cotton

Polyploidization has long been recognized as a driver for the evolutionary formation of superior plant traits coupled with gene expression novelty.However,knowledge of the effect of regulatory variation on expression changes following polyploidization remains limited.In this study,we characterized transcriptional regulatory divergence by comparing tetraploid cotton with its putative diploid ancestors.We identified 144,827,99,609,and 219,379 Tn5 transposase-hypersensitive sites(THSs)in Gossypium arboreum,G.raimondii,and G.hirsutum,respectively,and found that the conservation of promoter THSs was associated with coordination of orthologous genes expression.This observation was consistent with analysis of transcription-factor binding sites(TFBS)for 262 known motifs:genes with higher TFBS conservation scores(CS)showed less change than those genes with lower TFBS CS in expression levels.TFBS influenced by genomic variation were involved in the novel regulation networks between transcriptional factors and target genes in tetraploid cotton.We describe an example showing that the turnover of TFBS was linked to expression pattern divergence of genes involved in fiber development(fiber-related genes).Our findings reveal the regulatory divergence of the transcriptional network in cotton after polyploidization and characterizes the regulatory relationships of genes contributing to desirable traits.

Polyploidization Genetic Mechanism of Sugarcane Genome

The sugarcane genome polyploidization can reduce the pressure of gene evolution selection,promote the fixation of fine traits,and increase the biomass and economic value of sugarcane.This paper mainly introduced the origin of the sugarcane genome,the chromosome composition,the research progress of polyploidization genetic mechanism,in the hope of providing theoretical reference for sugarcane polyploidization breeding.

The genome of Orychophragmus violaceus provides genomic insights into the evolution of Brassicaceaepolyploidizationandits distinct traits

Orychophragmus violaceus,referred to as‘‘eryuelan’’(February orchid)in China,is an early-flowering ornamental plant.The high oil content and abundance of unsaturated fatty acids in O.violaceus seeds make it a potential high-quality oilseed crop.Here,we generated a whole-genome assembly for O.violaceus using Nanopore and Hi-C sequencing technologies.The assembled genome of O.violaceus was~1.3 Gb in size,with 12 pairs of chromosomes.Through investigation of ancestral genome evolution,we determined that the genome of O.violaceus experienced a tetraploidization event from a diploid progenitor with the translocated proto-Calepineae karyotype.Comparisons between the reconstructed subgenomes of O.violaceus identified indicators of subgenome dominance,indicating that subgenomes likely originated via allotetraploidy.O.violaceus was phylogenetically close to the Brassica genus,and tetraploidy in O.violaceus occurred approximately 8.57 million years ago,close in time to the whole-genome triplication of Brassica that likely arose via an intermediate tetraploid lineage.However,the tetraploidization in Orychophragmus was independent of the hexaploidization in Brassica,as evidenced by the results from detailed phylogenetic analyses and comparisons of the break and fusion points of ancestral genomic blocks.Moreover,identification of multi-copy genes regulating the production of high-quality oil highlighted the contributions of both tetraploidization and tandem duplication to functional innovation in O.violaceus.These findings provide novel insights into the polyploidization evolution of plant species and will promote both functional genomic studies and domestication/breeding efforts in O.violaceus.

A likely paleo-autotetraploidization event shaped the high conservation of Nyssaceae genome

Scientific knowledge about the ancestral genome of core eudicot plant kingdom can potentially have profound impacts on both basic and applied research,including evolution,genetics,genomics,ecology,agriculture,forestry,and global climate.To investigate which plant conserves best the core eudicots common ancestor genome,we compared Arcto-Tertiary relict Nyssaceae and 30 other eudicot plant families.The genomes of Davidia involucrata(a known living fossil),Camptotheca acuminata and Nyssa sinensis,one per existent genus of Nyssaceae,were performed comparative genomic analysis.We found that Nyssaceae originated from a single Nyssaceae common tetraploidization event(NCT)-autotetraploidization 28-31 Mya after the core eudicot common hexaploidization(ECH).We identified Nyssaceae orthologous and paralogous genes,determined its chromosomal evolutionary trajectory,and reconstructed the Nyssaceae most recent ancestor genome.D.involucrata genome contained the entire seven paleochromosomes and 17 ECH-generated eudicot common ancestor chromosomes and was the slowest in mutation among the analyzed 42 species of 31 plant families.Combing both its high retention of paleochromosomes and its low mutation rate,D.involucrata provides the best case in conservation of the core eudicot paleogenome.

Allotetraploidization event of Coptis chinensis shared by all Ranunculales

Coptis chinensis Franch.,also named Chinese goldthread is a member of Ranunculaceae in the order Ranunculales and represents an important lineage of early eudicots with traditional medicinal value.In our study,by using syntenic analysis combined with phylogenomic analysis of C.chinensis and four other representative genomes from basal and core eudicots,we confirmed that the WGD event in C.chinensis was shared by Aquilegia coerulea and Papaver somniferum L.and quickly occurred after Ranunculales diverged from other eudicots,likely a Ranunculales common tetraploidization(RCT).The synonymous nucleotide substitutions at synonymous sites distribution of syntenic blocks across these genomes showed that the evolutionary rate of the P.somniferum genome is faster than that of the C.chinensis genome by approximately 13.7%,possibly due to Papaveraceaes having an additional special tetraploidization event(PST).After Ks correction,the RCT dated to 115—130 million years ago(MYA),which was close to the divergence of Ranunculaceaes and Papaveraceaes approximately115.45—130.51 MYA.Moreover,we identified homologous genes related to polyploidization and speciation and constructed multiple sequence alignments with different reference genomes.Notably,the event-related subgenomes in the basal genomes all showed genomic fractionation bias,suggesting a likely allopolyploid nature of the RCT,PST and T-Alpha and T-Beta events in Tetracentron sinense.In addition,we detected that the sixteen P450 subfamilies were markedly expanded in the genomes of Ranunculales,and most of them were related to the RCT and PST events.We constructed a new platform for Early Eudicot Comparative Genomic Research(http://www.cgrpoee.top/index.html)to store more information.In summary,our findings support the WGD of C.chinensis shared by Ranunculales,which is likely an allotetraploidization event.This present effort offered new insights into the evolution of key polyploidization events and the genes related to secondary metabolites during the diversification of early eudicots.

The occurrence,inheritance,and segregation of complex genomic structural variation in synthetic Brassica napus

"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.

Convergent evolution of AP2/ERF Ⅲ and IX subfamilies through recurrent polyploidization and tandem duplication during eudicot adaptation to paleoenvironmental changes

Whole-genome duplication(WGD or polyploidization)has been suggested as a genetic contributor to angiosperm adaptation to environmental changes.However,many eudicot lineages did not undergo recent WGD(R-WGD)around and/or after the Cretaceous-Paleogene(K-Pg)boundary,times of severe environmental changes;how those plants survived has been largely ignored.Here,we collected 22 plants from major branches of the eudicot phylogeny and classified them into two groups according to the occurrence or absence of R-WGD:12 R-WGD-containing plants(R-WGD-Y)and 10 R-WGD-lacking plants(R-WGD-N).Subsequently,we identified 496 gene-rich families in R-WGD-Y and revealed that members of the AP2/ERF transcription factor family were convergently over-retained after R-WGDs and showed exceptional cold stimulation.The evolutionary trajectories of the AP2/ERF family were then compared between R-WGD-Y and R-WGD-N to reveal convergent expansions of the AP2/ERF Ⅲ and IX subfamilies through recurrent independent WGDs and tandem duplications(TDs)after the radiation of the plants.The expansions showed coincident enrichments in-times around and/or after the K-Pg boundary,when global cooling was a major environmental stressor.Consequently,convergent expansions and co-retentions of AP2/ERF Ⅲ C-repeat binding factor(CBF)duplicates and their regulons in different eudicot lineages contributed to the rewiring of cold-specific regulatory networks.Moreover,promoter analysis of cold-responsive AP2/ERF genes revealed an underlying cis-regulatory code(G-box:CACGTG).We propose a seesaw model of WGDs and TDs in the convergent expansion of AP2/ERF Ⅲ and IX genes that has contributed to eudicot adaptation during paleoenvironmental changes,and we suggest that TD may be a reciprocal/alternative mechanism for genetic innovation in plants that lack WGD.

Expression patterns and functional divergence of homologous genes accompanied by polyploidization in cotton(Gossypium hirsutum L.)

Naturally allotetraploid cotton has been widely used as an ideal model to investigate gene expression remodeling as a consequence of polyploidization.However,the global gene pattern variation during early fiber development was unknown.In this study,through RNA-seq technology,we comprehensively investigated the expression patterns of homologous genes between allotetraploid cotton(G.hirsutum)and its diploid progenitors(G.arboreum and G.raimondii)at the fiber early development stage.In tetraploid cotton,genes showed expression level dominance(ELD)bias toward the A genome.This phenomenon was explained by the up-/downregulation of the homologs from the nondominant progenitor(D genome).Gene ontology(GO)enrichment results indicated that the ELD-A genes might be a prominent cause responsible for fiber property change through regulating the fatty acid biosynthesis/metabolism and microtubule procession,and the ELD-D genes might be involved in transcription regulation and stress inducement.In addition,the number and proportion of completely A-and D-subfunctionalized gene were similar at different fiber development stages.However,for neofunctionalization,the number and proportion of reactivated D-derived genes were greater than those of A at 3 and 5 DPA.Eventually,we found that some homologous genes belonging to several specific pathways might create novel asymmetric transcripts between two subgenomes during polyploidization and domestication process,further making the fiber property meet the human demands.Our study identified determinate pathways and their involved genes between allotetraploid cotton and their progenitors at early fiber development stages,providing new insights into the mechanism of cotton fiber evolution.

Evolutionary genetics of wheat mitochondrial genomes

The Triticum-Aegilops complex provides ideal models for the study of polyploidization,and mitochondrial genomes(mtDNA)can be used to trace cytoplasmic inheritance and energy production following polyploidization.In this study,gapless mitochondrial genomes for 19 accessions of five Triticum or Aegilops species were assembled.Comparative genomics confirmed that the BB-genome progenitor donated mtDNA to tetraploid T.turgidum(genome formula AABB),and that this mtDNA was then passed on to the hexaploid T.aestivum(AABBDD).T urartu(AA)was the paternal parent of T.timopheevii(AAGG),and an earlier Ae.tauschii(DD)was the maternal parent of Ae.cylindrica(CCDD).Genic sequences were highly conserved within species,but frequent rearrangements and nuclear or chloroplast DNA insertions occurred during speciation.Four highly variable mitochondrial genes(atp6,cob,nad6,and nad9)were established as marker genes for Triticum and Aegilops species identification.The BB/GG-specific atp6 and cob genes,which were imported from the nuclear genome,could facilitate identification of their diploid progenitors.Genic haplotypes and repeat-sequence patterns indicated that BB was much closer to GG than to Ae.speltoides(SS).These findings provide novel insights into the polyploid evolution of the Triticum/Aegilops complex from the perspective of mtDNA,advancing understanding of energy supply and adaptation in wheat species。

The lectin gene TRpL1 of tetraploid Robinia pseudoacacia L.response to salt stress

Lectins are natural proteins in animals,plants,and microorganisms and can be divided into 12 families.These lectins play important roles in various environmental stresses.Some polyploid plants show tolerance to environmental stresses and to insect pests.However,the mechanism of stress tolerance is unclear.Tetraploid Robinia pseudoacacia(4×)under salt stress showed higher tolerance than diploid R.pseudoacacia(2×).As lectin can improve stress tolerance,it was questioned whether the stress resistance of polyploid plants was related to the lectin protein.In this study,salt resistance of lectin gene TRpL1 was verified by its over-expression in plants.In addition,salt resistance of lectin protein by E.coli strains was detected.The data revealed that the over-expression transgenic plants of TRpL1 showed better salt tolerance than control plants under salt stress,and the TRpL1-expressing strain also grew better in the medium with added NaCl.Therefore,tetraploid plants can resist salt stress through TRpL1 protein regulation.

Megamitochondria Initiate Differentiation of Monolayer Cells into Detached Dome Cells That Proliferate by a Schizogony-Like Amitotic Process

Mitonucleon-initiated dome formation involves structural changes occurring over a 20 to 24 hour period in monolayer cells induced by a serum factor. The earliest observable change is the fusion of monolayer cells into a syncytium in which nuclei aggregate and become surrounded by a membrane that stains for endogenous biotin. Each of these structures is further surrounded by a fraction of the mitochondria that arise in the syncytium following initiation of dome formation. The mitochondria fuse around the chromatin aggregate in a structure we have called a mitonucleon. Within mitonucleons, a gaseous vacuole is generated that can be seen in protrusions of the apical membrane pressuring chromatin into a pyknotic state. Eventually that pressure, together with whatever enzymatic changes have occurred in the bolus of chromatin, results in DNA fragmentation. The fragments drawn out through the syncytium by a unipolar spindle are arrayed in a configuration that appears open both to epigenetic changes and to DNA repair and replication by polyteny. The fragmented DNA stretched across the syncytial space, hardly detectable by light microscopy, becomes visible approximately half way through the differentiation as the filaments thicken in what looks like replication by polyteny. This “recycling” of attached monolayer cells into detached dome cells must include DNA replication since the number of cells in the resulting domes is greater than the number of monolayer cells by 30% or more. The resulting DNA associates into a mass of chromatin which will “segment” into polyploid structures and then into what appear to be diploid nuclei over a period of 2 to 4 hours. When the layer of nuclei has filled the syncytium, the nuclei are cellularized, forming dome cells rising up from the monolayer and arching over a fluid cavity. Dome cells can extend into gland-like structures by the same mitonucleon dependent amitotic process observed in dome formation. Some of the characteristics of this process resemble the amitotic process of schizogony among single-celled eukaryotic parasites of the apicomplexan phylum. Mitonucleon initiated amitotic proliferation results in synthesis of dozens of dome cell nuclei in a period of 20 to 24 hours, so it is much more efficient than mitosis. Cells generated by this process and their progeny would also not be sensitive to agents that inhibit mitosis suggesting that the process, as an alternative to mitosis, might be activated in cancers that become resistant to some cytotoxic drugs.

Genomic footprints of wheat evolution in China reflected by a Wheat660K SNP array

Common wheat(Triticum aestiuum L.)is one of the most important crops because it provides about 20%of the total calories for humans.T.aestiuum is an excellent modern species for studying concerted evolution of sub-genomes in polyploid species,because of its large chromosome size and three well-known genome donors.Establishment of common wheat genome reference sequence and development of high-density SNP chips provide an excellent foundation to answer questions of wheat evolution and breeding at the genomic level.By genotyping more than 600 accessions of common wheat and their diploid and tetraploid ancestors using a Wheat660 K SNP array,we found dramatic genome changes due to tetraploidization and hexaploidization,in contrast to weaker influences of domestication and breeding on them.Further,since common wheat was introduced in China in 1500 BCE,Chinese landraces formed two subgroups(T.aestiuum-L1 and T.aestiuum-L2)with considerably diverse geographic distributions and agronomic traits.T.aestiuum-L2,mainly distributed in central and east China is found to have more but smaller oval grains with early maturity characteristics.We found that variation and selection in intergenic regions of the A and B sub-genomes dominated this differentiation,in which chromosomes 7 A and 3 B took the leading roles due to the existence of putative genes related to defense responses and environmental adaption in the highly differentiated regions.Large haplotype blocks were detected on 3 B(232.6-398.3 Mb)and 7 A(211.7-272.9 Mb)in the landraces,forming two distinct haplotypes,respectively.We discovered that artificial crosses in breeding promoted recombination in the whole genome,however,this recombination and differentiation was highly asymmetric among the three sub-genomes in homoeologous regions.In addition,we found that the wide use of European and northern American cultivars in breeding at early era,led dramatic changes in Chinese wheat genome,whereas,the recent breeding functioned to optimize it.This study will provide the insight for reconsideration of wheat evolution and breeding,and a new strategy for parent selection in breeding.

Roles of cell fusion, hybridization and polyploid cell formation in cancer metastasis

Cell-cell fusion is a normal biological process playing essential roles in organ formation and tissue differentiation,repair and regeneration.Through cell fusion somatic cells undergo rapid nuclear reprogramming and epigenetic modifications to form hybrid cells with new genetic and phenotypic properties at a rate exceeding that achievable by random mutations.Factors that stimulate cell fusion are inflammation and hypoxia.Fusion of cancer cells with non-neoplastic cells facilitates several malignancy-related cell phenotypes,e.g.,reprogramming of somatic cell into induced pluripotent stem cells and epithelial to mesenchymal transition.There is now considerable in vitro,in vivo and clinical evidence that fusion of cancer cells with motile leucocytes such as macrophages plays a major role in cancer metastasis.Of the many changes in cancer cells after hybridizing with leucocytes,it is notable that hybrids acquire resistance to chemo-and radiation therapy.One phenomenon that has been largely overlooked yet plays a role in these processes is polyploidization.Regardless of the mechanism of polyploid cell formation,it happens in response to genotoxic stresses and enhances a cancer cell’s ability to survive.Here we summarize the recent progress in research of cell fusion and with a focus on an important role for polyploid cells in cancer metastasis.In addition,we discuss the clinical evidence and the importance of cell fusion and polyploidization in solid tumors.

Genome editing opens a new era of genetic improvement in polyploid crops

Sequence-specific nucleases(SSN) that generate double-stranded DNA breaks(DSBs) in genes of interest are the key to site-specific genome editing in plants. Genome editing has developed into one method of reducing undesirable traits in crops by the induction of knockout mutations. Different SSN-mediated genome-editing systems, including LAGLIDADG homing endonucleases or meganucleases, zinc-finger nucleases, transcription activator-like effector nucleases and clustered regularly interspaced short palindromic repeats, are emerging as robust tools for introducing functional mutations in polyploid crops including citrus, wheat, cotton, soybean, rapeseed, potato, grapes, Camelina sativa,dandelion, and tobacco. The approach utilizes knowledge of biological mechanisms for targeted induction of DSBs and their error-prone repair, allowing highly specific changes at designated genome loci. In this review, we briefly describe genome-editing technologies and their application to genetic improvement of polyploid crops.

Induction and characterization of polyploids from seeds of Rhododendron fortunei Lindl.

Most Rhododendron species are ornamental flowering species widely distributed in Asia,North America,and West Europe.Rhododendron fortunei,one of the endemic Rhododendron species in China,has beautiful flowers with bright colors and is being exploited to meet the needs of the flower market.Polyploid plants usually show superiority in growth,disease resistance,and adaption over their diploid relatives.Here,we report the first case of polyploid induction in R.fortunei.In order to induce polyploidy in R.fortunei,germinating seeds were treated with different concentrations of oryzalin for 16 h.By evaluating ploidy level with flow cytometry,a total of 34 polyploid R.fortunei lines,including 27 tetraploid lines and seven octoploid lines,were obtained.A comparison of treatments indicated that 7.5 mg L^-1 oryzalin was the optimal concentration for polyploid induction in seeds of R.fortunei.Compared with diploid plants,tetraploid and octoploid plants exhibited slower growth rates and had thicker and rounder curled leaves with more leaf epidermal hairs.Moreover,larger stomata at lower density were also observed in the leaves of polyploid plants.Chlorophyll contents were also significantly increased in polyploid plants,which leads to a darker green leaf color.Both small and large individuals exhibiting the same characteristics were observed among the obtained tetraploid plants.Overall,our study establishes a feasible method for polyploid induction in R.fortunei,thus providing a basis for breeding new R.fortunei varieties.

Mechanisms involved in selecting and maintaining neuroblastoma cancer stem cell populations, and perspectives for therapeutic targeting

Pediatric neuroblastomas(NBs)are heterogeneous,aggressive,therapy-resistant embryonal tumours that originate from cells of neural crest(NC)origin and in particular neuroblasts committed to the sympathoadrenal progenitor cell lineage.Therapeutic resistance,post-therapeutic relapse and subsequent metastatic NB progression are driven primarily by cancer stem cell(CSC)-like subpopulations,which through their self-renewing capacity,intermittent and slow cell cycles,drug-resistant and reversibly adaptive plastic phenotypes,represent the most important obstacle to improving therapeutic outcomes in unfavourable NBs.In this review,dedicated to NB CSCs and the prospects for their therapeutic eradication,we initiate with brief descriptions of the unique transient vertebrate embryonic NC structure and salient molecular protagonists involved NC induction,specification,epithelial to mesenchymal transition and migratory behaviour,in order to familiarise the reader with the embryonic cellular and molecular origins and background to NB.We follow this by introducing NB and the potential NC-derived stem/progenitor cell origins of NBs,before providing a comprehensive review of the salient molecules,signalling pathways,mechanisms,tumour microenvironmental and therapeutic conditions involved in promoting,selecting and maintaining NB CSC subpopulations,and that underpin their therapy-resistant,self-renewing metastatic behaviour.Finally,we review potential therapeutic strategies and future prospects for targeting and eradication of these bastions of NB therapeutic resistance,post-therapeutic relapse and metastatic progression.

Cytochalasin B induced triploidy in Penaeus chinensis

ＣｙｔｏｃｈａｌａｓｉｎＢｉｎｄｕｃｅｄｔｒｉｐｌｏｉｄｙｉｎＰｅｎａｅｕｓｃｈｉｎｅｎｓｉｓ￥ＢａｏＺｈｅｎｍｉｎ，ＺｈａｎｇＱｕａｎｑｉ，ＷａｎｇＨａｉａｎｄＤａｉＪｉｘｕｎ（ＲｅｃｅｉｖｅｄＡｐｒｉｌ５，１９９３；ａｃｃｅｐｔｅｄＡｕｇｕｓｔ１...

Difference Analysis of Liver Metabolic Response Between Diploid and Triploid Rainbow Trout Oncorhynchus mykiss Under Fishing Stress

To elucidate the effects of fishing stress on the liver glucose metabolism of both diploid and triploid female rainbow trouts as well as differences in their stress response,blood and liver tissues were collected from 0 h to 24 h after the fishing stress.Blood indexes,such as the levels of white blood cells and red blood cells,cortisol,glucose and lactic acid,as well as activities of key enzymes of the glucose metabolism in the liver,were measured.Furthermore,the mRNA expressions of glucocorticoid receptors and enzymes related to energy metabolism were assessed.The results showed that fishing stress exerted significant effects on blood physiological and biochemical indexes and liver glucose metabolism.Differences were found between diploid and triploid female rainbow trouts in the liver glucose metabolism pathway,as well as the level and performance during stress.The basic glucose metabolism intensity of the triploid liver was higher than that of the diploid liver;however,the hepatic glycogen reserve was lower in the triploid liver.After fishing stress,triploid trouts entered the immunosuppressive state earlier than diploid trouts.Triploid trouts also showed an earlier and stronger stress reaction than diploid trouts,while their energy allocation ability and immune recovery ability were weaker than those of diploid trouts.These results showed that the regulatory ability of diploid female rainbow trouts in response to fishing stress was better than that of triploid trouts.

Polyploid Gene Expression and Regulation in Polysomic Polyploids

Polyploidization is one of the most crucial pathways in introducing speciation and broadening biodiversity, especially in the Plant Kingdom. Although the majority of studies have focused only on allopolyploid or disomic polyploids, polysomic polyploid species have occurred frequently in higher plants. Due to the occurrence of the capabilities of more copies of alleles in a locus which can have additive dosage effects and/or allelic interactions, polysomic polyploids can lead to unique gene regulations to silence or adjust the expression level to create variations in organ size, metabolic products, and abiotic stress tolerance and biotic stress resistance, etc. This review aims to comprehensively summarize the contemporary understanding and findings concerning the molecular mechanisms of gene expression as well as gene regulation in natural typed and resynthesized polysomic polyploid plants. The review investigates the molecular level of phenomena in polysomic polyploid plants such as 1) typically enlarging organ size and stabilizing meiosis, 2) increasing phytochemical content and metabolic products, 3) enhancing the ability to adapt with biotic and abiotic stress, and 4) changing in gene regulation to silence or adjust the expression levels involve in sequence elimination, methylation, gene suppression, subfunctionalization, neo-functionalization, and transposon activation.