Introgression of sharp eyespot resistance from Dasypyrum villosum chromosome 2VL into bread wheat

Wheat sharp eyespot, a stem disease caused by the soilborne fungus Rhizoctonia cerealis van der Hoeven,has become a threat to wheat production worldwide. Exploiting resistance resources from wild relatives of wheat is a promising strategy for controlling this disease. In this study, a new wheat–Dasypyrum villosum T2DS·2V#4L translocation line in the background of Chinese Spring(CS) showed stable resistance to R. cerealis. Introgression of the T2DS·2V#4L chromosome into wheat cultivar Aikang 58 by backcrossing produced a marked increase in sharp eyespot resistance in NIL-T2DS·2V#4L in comparison with NILT2DS·2DL, and no detrimental effects of 2V#4L on agronomic traits were observed in the BC2F2, BC2F2:3,and BC2F2:4generations. Flow-sorted sequencing of 2V#4L yielded 384.3 Mb of assembled sequence, and8836 genes were predicted of which 6154 had orthologs in at least one of the 2AL, 2BL, and 2DL arms of CS, whereas 1549 genes were unique to 2V#4L. About 100,000 SNPs were detected in genes of 2V#4L and2DL in 10 sequenced bread wheat cultivars. A Kompetitive Allele Specific Polymerase chain reaction and30 conserved ortholog sequence markers were developed to trace the 2V#4L chromatin in wheat backgrounds. T2DS·2V#4L compensating translocation lines represent novel germplasm with sharp eyespot resistance and the markers will allow rapid detection in breeding programs.

Corrigendum to“Introgression of sharp eyespot resistance from Dasypyrum villosum chromosome 2VL into bread wheat”[Crop J.11(2023)1512–1520]

The authors regret to report some missing information in the authorship and associated changes of the paper.On page 1512,the author information reads:“Caiyun Liu a,Wei Guo a,Yang Wang b,Bisheng Fu a,Jaroslav Dolezel c,Ying Liu a,Wenling Zhai a,Mahmoud Said c,d,István Molnár c,d,e,Katerina Holušovác,Ruiqi Zhang b,*,Jizhong Wu a,f,g,*”.It should be changed to“Caiyun Liu a,1,Wei Guo a,1,Yang Wang b,Bisheng Fu a,Jaroslav Dolezel c,Ying Liu a,Wenling Zhai a,Mahmoud Said c,d,István Molnár c,d,e,Katerina Holušovác,Ruiqi Zhang b,*,Jizhong Wu a,f,g,*”.On page 1512 in the footnote,the following sentence should be added below the corresponding authors’information:1 These authors contributed equally to this work.The correction has been updated above.The authors would like to apologize for any inconvenience caused.

Overexpression of IbPAL1 promotes chlorogenic acid biosynthesis in sweetpotato

Sweetpotato[Ipomoea batatas(L.)Lam.],a food crop with both nutritional and medicinal uses,plays essential roles in food security and health-promoting.Chlorogenic acid(CGA),a polyphenol displaying several bioactivities,is distributed in all edible parts of sweetpotato.However,little is known about the specific metabolism of CGA in sweetpotato.In this study,IbPAL1,which encodes an endoplasmic reticulum-localized phenylalanine ammonia lyase(PAL),was isolated and characterized in sweetpotato.CGA accumulation was positively associated with the expression pattern of IbPAL1 in a tissue-specific manner,as further demonstrated by overexpression of IbPAL1.Overexpression of IbPAL1 promoted CGA accumulation and biosynthetic pathway genes expression in leaves,stimulated secondary xylem cell expansion in stems,and inhibited storage root formation.Our results support a potential role for IbPAL1 in sweetpotato CGA biosynthesis and establish a theoretical foundation for detailed mechanism research and nutrient improvement in sweetpotato breeding programs.

Development and molecular analysis of a novel acetohydroxyacid synthase rapeseed mutant with high resistance to sulfonylurea herbicides

With the increasing promotion of simplified rapeseed cultivation in recent years,the development of cultivars with high resistance to herbicides is urgently needed.We previously developed M342,which shows sulfonylurea herbicide resistance,by targeting acetohydroxyacid synthase(AHAS),a key enzyme in branched-chain amino acid synthesis.In the present study,we used a progeny line derived from M342 for an additional round of ethyl methane sulfonate mutagenesis,yielding the novel mutant DS3,which harbored two mutations in AHAS genes and showed high sulfonylurea resistance.One mutation was the substitution Trp574 Leu,as in M342,according to Arabidopsis protein sequencing.The other site was a newly recognized substitution,Pro197 Leu.A KASP marker targeting Pro197 Leu was developed and reliably predicted the response to sulfonylurea herbicides in the F2 population.The combination of Trp574 Leu and Pro197 Leu in DS3 produced a synergistic effect that greatly increased herbicide resistance.Analysis of the protein structures of AHAS1 and AHAS3 in wild-type and single-gene mutant plants revealed three-dimensional protein conformational changes that could account for differences in herbicide resistance characteristics including toxicity tolerance,AHAS enzyme activity,and AHAS gene expression.

Intron-targeted gene insertion in rice using CRISPR/Cas9: A case study of the Pi-ta gene

Intron-targeted gene insertion strategy using CRISPR/Cas9(clustered regularly interspaced short palindromic repeats/CRISPR-associated Cas9) has been shown to be a potential tool for crop genetic improvement by targeted mutagenesis or gene replacement of an elite allele into widely cultivated rice varieties. The rice blast resistant protein Pi-ta, differs from its susceptible counterpart, pi-ta, by a single amino acid in exon 2. To create new materials resistant to the rice blast disease, we inserted a genomic fragment containing the exon 2 and 3′ untranslated region(3′ UTR) of Pi-ta into intron 1 of pi-ta in rice materials susceptible to rice blast using the intron-targeted insertion strategy. The gene insertion frequency was3.8%. Several novel transgene-free progeny with stably inherited homozygous insert were identified in the T_1 generation, which have been crossed to rice germplasm bearing other resistance gene(R gene) for pyramiding of R genes. This work verified the feasibility of using the genome editing technology in improvement of qualitative agronomic trait in crops.

Meta-analysis of QTL for Fusarium head blight resistance in Chinese wheat landraces

Epidemics of Fusarium head blight(FHB), incited by Fusarium graminearum Schwabe, in wheat cause significant reductions in grain yield and quality. Numerous quantitative trait loci(QTL) for FHB resistance have been reported from Chinese sources. However, the relationships among QTL from different landraces have not been characterized. We earlier mapped QTL for FHB resistance using low-density maps developed from five recombinant inbred line(RIL) populations involving Chinese landraces ‘Haiyanzhong’(HYZ),‘Wangshuibai’(WSB), ‘Baishanyuehuang’(BSYH), ‘Huangfangzhu’(HFZ), and‘Huangcandou’(HCD) as FHB resistant parents. In this study, we used maps of single nucleotide polymorphisms(SNP) developed from the five populations and identified 31 QTL on 16 chromosomes;10 QTL were new. We constructed a consensus map and identified six meta-QTL(MQTL) and SNP within the MQTL regions using meta-analysis. Two of the MQTL were on chromosome 3 BS(3 BSd and 3 BSc), and one on each of chromosomes 3A, 2D, 3D,and 4D. Twenty-two SNP closely linked to MQTL were converted into breeder friendly Kompetitive Allele Specific Polymerase Chain Reaction(KASP) assays, which should be useful for marker-assisted selection in breeding programs.

Identification and Genetic Analysis of a Novel Allelic Variation of Brittle-1 with Endosperm Mutant in Maize

Endosperm mutants are critical to the studies on both starch synthesis and metabolism and genetic improvement of starch quality in maize.In the present study,a novel maize endosperm mutant A0178 of natural variation was used as the experimental material and identified and then characterized.Through phenotypic identification,genetic analysis,main ingredients measurement and embryo rescue,development of genetic mapping population from A0178,the endosperm mutant gene was located.The results showed that the mutant exhibited extremely low germination ability as attributed to the inhibited embryo development,and amounts of sugars were accumulated in the mutant seeds and more sugars content was detected at 23 days after pollination(DAP)in A0178 than B73.Employing genetic linkage analysis,the mutant trait was mapped in the bin 5.04 on chromosome 5.Sequence analysis showed that two sites of base transversion and insertion presented in the protein coding region and non-coding region of the mutant brittle-1(bt1),the adenylate translocator encoding gene involved in the starch synthesis.The single base insertion in the coding region cause frameshift mutation,early termination and lose of function of Brittle-1(BT1).All results suggested that bt1 is a novel allelic gene and the causal gene of this endosperm mutant,providing insights on the mechanism of endosperm formation in maize.

Pathogen Identification of Wheat Crown Rot and Control Effects of Different Fungicides

[ Objectives ] The paper aimed to reduce the damage of wheat crown rot caused by Fusarium graminearum on wheat production. [ Methods ] Pathogens were isolated from wheat crown rot samples collected in fields, and the major pathogenic fungi were determined as F. graminearum through molecular techniques. Different fungicides were administrated at seedling stage and reviving stage to control the disease. [ Results] There were significant differences in control effects against crown rot among different fungicides. Tebuconazole ·prochloraz mixture and Carbendazim · triadimefon mixture had good control effects, while such single agents as Tebuconnazole and Difenoconazole· propicondzole had good control effects as well. [ Conclusions] Seed dressing with agents could significantly reduce the incidence rate of crown rot at seedling stage, and stem spraying at reviving stage had better control effect.

Overexpression of phosphatidylserine synthase IbPSS1 affords cellular Na+homeostasis and salt tolerance by activating plasma membrane Na^(+)/H^(+)antiport activity in sweet potato roots

Phosphatidylserine synthase(PSS)-mediated phosphatidylserine(PS)synthesis is crucial for plant development.However,little is known about the contribution of PSS to Na^(+)homeostasis regulation and salt tolerance in plants.Here,we cloned the IbPSS1 gene,which encodes an ortholog of Arabidopsis AtPSS1,from sweet potato(Ipomoea batatas(L.)Lam.).The transient expression of IbPSS1 in Nicotiana benthamiana leaves increased PS abundance.We then established an efficient Agrobacterium rhizogenes-mediated in vivo root transgenic system for sweet potato.Overexpression of IbPSS1 through this system markedly decreased cellular Na^(+)accumulation in salinized transgenic roots(TRs)compared with adventitious roots.The overexpression of IbPSS1 enhanced salt-induced Na^(+)/H^(+)antiport activity and increased plasma membrane(PM)Ca^(2+)-permeable channel sensitivity to NaCl and H2O2 in the TRs.We confirmed the important role of IbPSS1 in improving salt tolerance in transgenic sweet potato lines obtained from an Agrobacterium tumefaciens-mediated transformation system.Similarly,compared with the wild-type(WT)plants,the transgenic lines presented decreased Na^(+)accumulation,enhanced Na^(+)exclusion,and increased PM Ca^(2+)-permeable channel sensitivity to NaCl and H2O2 in the roots.Exogenous application of lysophosphatidylserine triggered similar shifts in Na^(+)accumulation and Na^(+)and Ca^(2+)fluxes in the salinized roots of WT.Overall,this study provides an efficient and reliable transgenic method for functional genomic studies of sweet potato.Our results revealed that IbPSS1 contributes to the salt tolerance of sweet potato by enabling Na^(+)homeostasis and Na^(+)exclusion in the roots,and the latter process is possibly controlled by PS reinforcing Ca^(2+)signaling in the roots.

Identification of a novel gain-of-function mutant allele,slr1-d5,of rice DELLA protein

Controling the height of crops plays a crucial role for their yields. The large scale utilization of semi-dwarf varieties has greatly improved crop yield, providing an effective support for world food security. In rice, a main food for over half of the world’s population, a number of dwarf loci have been identiifed. However, most of them are recessive, such as the ‘green revolution’ genesd1. To gain more beneifcial loci for rice breeding programs, exploring new mutations is needed, especialy the dominant loci which can be used broadly for hybrid breeding. Here, we isolated a novel dominant dwarf rice mutant, slr1-d5. Al of the internodes ofslr1-d5are reduced. We ifnd that the responsiveness ofslr1-d5to gibberelin （GA）, GA3, was signiifcantly reduced. Map-based cloning revealed that the dominant dwarifsm ofslr1-d5was caused by an amino acid substitution in the N-terminal TVHYNP domain of rice DELLA protein, SLR1, where the conserved amino acid Pro （P） was substituted to His （H）. Our ifndings not only further prove the pivotal role of TVHYNP motif in regulating SLR1 stability, but also provide a new dwarf source for improvement of rice germplasms.

Dynamic patterns of the translatome in a hybrid triplet show translational fractionation of the maize subgenomes

Heterosis,the phenomenon in which hybrids outperform their parents,has been utilized in maize(Zea mays L.)for over 100 years.To provide a more complete understanding of heterosis,we collected a comprehensive transcriptome and translatome dataset on seedling leaves for B73,Mo17,and their F1 hybrid,which provided a dynamic landscape of transcriptomic and translatomic variation in maize.Although additivity accounted for a large proportion of variation at two omics-levels,an elevated nonadditive effect was observed in the translatome,especially in the translated subgenome maize1 genes,and the genes that switched from additivity in the transcriptome to nonadditivity in the translatome were significantly enriched in the subgenome maize1.Many genes with allele-specific expression and translation show dramatic regulatory switches between the transcriptome and translatome,and partial genes with allele-specific translation underlying regulatory mechanism also exhibited subgenome bias.Interestingly,we found the translated isoforms show different expression patterns compared with transcriptome and more genes changed their dominant isoforms during the genetic flow from parents to the hybrid at the translatome level.The translated genes with switched dominant isoforms significantly biased to the subgenome maize2 while genes with conserved dominant isoforms significantly enriched in subgenome maize1.Together,the dynamic changed patterns in translatome across hybrid and parental lines show translational fractionation of the maize subgenomes,which may be associated with heterosis in maize and provides a potential theoretical basis for breeding.

Genetic Analysis of Grain Yield in a 7×7 Diallel Cross F_2 Population of Wheat(T.Aestivum L.)

In order to obtain genetic information for grain yield, seven genetically diverse wheat cultivars were crossed in an incomplete diallel to study the inheritance of grain yield using F_2 progenies for two years. Significant differences were observed among genotype, year and genotype × year interaction for grain yield, and both general combining ability(GCA) and specific combining ability(SCA) were also highly significant for grain yield, suggesting that the trait was controlled by both additive and non-additive effect. The GCA estimates revealed that the best combiners for grain yield were Yangmai 5 and Ningmai 9. Adequacy tests revealed that data of grain yield was fully adequate for genetic interpretation. Over-dominance genetic effects were important for the expression of grain yield. Grain yield exhibited moderately high value of narrow sense heritability(h_N^2=66.98% and h_N^2=72.37%).

Variations of DON Content in Grain during Wheat Tempering at Different Temperatures

[Objective] The aim of this study was to observe variations of DON content in grain of two wheat cultivars during tempering at different temperatures, and explore the possible causes of the variations. [Method] Two naturally Fusarium-infested wheat samples Youmai 3 and Yangmai 14 were selected as experimental materials. Tempering was carried out at different temperature(15, 25 and 35 ℃) for 48 h. During tempering, wheat grain samples were collected every 8 h. DON contents in tempered grain were measured by HPLC coupled with UV detector. [Result] For Youmai 3, DON contents were in the ranges of 3.94-12.49, 4.26-6.11 and 3.41-7.91 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 32ndhour at 15 ℃, the 8thhour at 25 ℃ and the 32ndhour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 175.1%, 27.5% and 7.2%, respectively. For Yangmai 14, DON contents were in the ranges of 0.55-1.56, 0.39-0.77 and 0.57-3.17 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 24thhour at 15 ℃, the 40thhour at 25 ℃ and the 48thhour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 94.5% at 15 ℃ and 456.1% at 35 ℃, respectively, whereas it was decreased by 35.0% at 25 ℃. From the point of view of reducing DON level, 15 ℃ was not reasonable for the tempering of both wheat cultivars, and tempering at 35 ℃ for 16 h and tempering at 25 ℃ for 24 h appeared to be desirable for Youmai 3 and Yangmai 14, respectively. [Conclusion] The results suggested controlling the tempering temperature and time would be helpful to reduce DON level in grain.

PnSCR82,a small cysteine-rich secretory protein of Phytophthora nicotianae,can enhance defense responses in plants

A number of plant pathogenic species of Phytophthora are known to produce different classes of secretory proteins during interactions with their hosts.Although several small cysteine-rich(SCR)secretory proteins,conserved in oomycete pathogens,have been identified in Phytophthora,their specific involvement in these interactions remains unknown.In this study,an SCR effector encoded by Pn SCR82 in P.nicotianae was identified and shown to have similarities to P.cactorum phytotoxic protein,Pc F(Phytophthora cactorum Fragaria).Agroinfection with potato virus X vector,Pn SCR82,was capable of inducing plant hypersensitive cell death in Nicotiana benthamiana and Solanum lycopersicum.Real-time PCR results indicated that transiently expressed Pn SCR82 in N.benthamiana leaves activated the jasmonate,salicylic acid and ethylene signaling pathways.Transient expression of Pn SCR82 enhanced plant resisitance to P.capsici.In summary,our results demonstrated that P.nicotianae Pn SCR82 elicits defensive responses in N.benthamiana and may potentially play a significant role in future crop protection programs.

BnaSD.C3 is a novel major quantitative trait locus affecting semi-dwarf architecture in Brassica napus L.

Plant height is a key plant architectural trait that affects the seed yield,harvest index and lodging resistance in Brassica napus L.,although the genetic mechanisms affecting plant height remain unclear.Here,a semi-dwarf mutant,df34,was obtained by ethyl methanesulphonate-induced mutagenesis.Genetic analysis showed that the semi-dwarf phenotype is controlled by one semi-dominant gene,which was located on chromosome C03 using a bulked segregant analysis coupled with whole-genome sequencing,and this gene was named BnaSD.C3.Then BnaSD.C3 was fine-mapped to a 297.35-kb segment of the“Darmor-bzh”genome,but there was no potential candidate gene for the semi-dwarf trait underlying this interval.Furthermore,the interval was aligned to the Zhongshuang 11 reference genome.Finally,combining structural variation analysis,transcriptome sequencing,phytohormone analyses and gene annotation information,BnaC03G0466900ZS and BnaC03G0478900ZS were determined to be the most likely candidate genes affecting the plant height of df34.This study provides a novel major locus for breeding and new insights into the genetic architecture of plant height in B.napus.

A nonsynonymous mutation in an acetolactate synthase gene (Gh_D10G1253) is required for tolerance to imidazolinone herbicides in cotton

Background Herbicide tolerance in crops enables them to survive when lethal doses of herbicides are applied to surrounding weeds.Herbicide-tolerant crops can be developed through transgenic approaches or traditional mutagenesis approaches.At present,no transgenic herbicide tolerant cotton have been commercialized in China due to the genetically-modified organism(GMO)regulation law.We aim to develop a non-transgenic herbicide-tolerant cotton through ethyl methanesulfonate(EMS)mutagenesis,offering an alternative choice for weed management.Results Seeds of an elite cotton cultivar Lumianyan 37(Lu37)were treated with EMS,and a mutant Lu37-1 showed strong tolerance to imidazolinone(IMI)herbicides was identified.A novel nonsynonymous substitution mutation Ser642Asn at acetolactate synthase(ALS)(Gh_D10G1253)in Lu37-1 mutant line was found to be the potential cause to the IMI herbicides tolerance in cotton.The Ser642Asn mutation in ALS did not present among the genomes of natural Gossypium species.Cleaved amplified polymorphic sequence(CAPS)markers were developed to identify the ALS mutant allele.The Arabidopsis overexpressing the mutanted ALS also showed high tolerance to IMI herbicides.Conclusion The nonsynonymous substitution mutation Ser642Asn of the ALS gene Gh_D10G1253 is a novel identi-fied mutation in cotton.This substitution mutation has also been identified in the orthologous ALS genes in other crops.This mutant ALS allele can be used to develop IMI herbicide-tolerant crops via a non-transgenic or transgenic approach.

Expansion and improvement of ChinaMu by MuT-seq and chromosome-level assembly of the Mu-starter genome

ChinaMu is the largest sequence-indexed Mutator(Mu)transposon insertional library in maize(Zea mays).In this study,we made significant improvements to the size and quality of the ChinaMu library.We developed a new Mu-tag isolation method Mu-Tn5-seq(MuT-seq).Compared to the previous method used by ChinaMu,MuT-seq recovered 1/3 more germinal insertions,while requiring only about 1/14 of the sequencing volume and 1/5 of the experimental time.Using MuT-seq,we identified 113,879 germinal insertions from 3,168 Mu-active F1 families.We also assembled a high-quality genome for the Mu-active line Mu-starter,which harbors the initial active MuDR element and was used as the pollen donor for the mutation population.Using the Mu-starter genome,we recovered 33,662(15.6%)additional germinal insertions in 3,244(7.4%)genes in the Mu-starter line.The Mu-starter genome also improved the assignment of 117,689(54.5%)germinal insertions.The newly upgraded ChinaMu dataset currently contains 215,889 high-quality germinal insertions.These insertions cover 32,224 pan-genes in the Mu-starter and B73Ref5 genomes,including 23,006(80.4%)core genes shared by the two genomes.As a test model,we investigated Mu insertions in the pentatricopeptide repeat(PPR)superfamily,discovering insertions for 92%(449/487)of PPR genes in ChinaMu,demonstrating the usefulness of ChinaMu as a functional genomics resource for maize.

Creating a novel herbicide-tolerance OsALS allele using CRISPR/Cas9-mediated gene editing

Weeds and weedy rice plague commercial rice fields in many countries. Developingherbicide-tolerance rice is the most efficient strategy to control weed proliferation. CRISPR/Cas9-mediated gene editing, which generates small InDels and nucleotide substitutions atand around target sites using error-prone non-homologous end joining DNA repairing, hasbeen widely adopted for generation of novel crop germplasm with a wide range of geneticvariation in important agronomic traits. We created a novel herbicide-tolerance allele inrice by targeting the acetolactate synthase (OsALS) gene using CRISPR/Cas9-mediated geneediting. The novel allele (G628W) arose from a G-to-T transversion at position 1882 of OsALSand conferred a high level of herbicide tolerance. Transgene-free progeny carryinghomozygous G628W allele were identified and showed agronomic performance similar tothat of wild-type plants, suggesting that the G628W allele is a valuable resource fordeveloping elite rice varieties with strong herbicide tolerance. To promote use of the G628Wallele and to accelerate introgression and/or pyramiding of the G628W allele with other elitealleles, we developed a DNA marker for the G628W allele that accurately and robustlydistinguished homozygous from heterozygous segregants. Our result further demonstratesthe feasibility of CRISPR/Cas9-mediated gene editing in creating novel genetic variation forcrop breeding.

Improved oxidative tolerance in suspension‐cultured cells of C_4-pepctransgenic rice by H_2O_2 and Ca^(2+)under PEG-6000

To understand the molecular responses of PC （Overexpressing the maize C4‐pepc gene, which encodes phosphoenolpyruvate carboxylase （PEPC））, to drought stress at cel level, we analyzed changes in the levels of signaling molecules （hydrogen peroxide （H2O2）, calcium ion （Ca2t）, and nitric oxide （NO）） in suspension‐cultured PC and wild‐type （WT） rice （Oryza sativa L.） cel under drought stress induced by 20%polyethylene glycol 6000 （PEG‐6000）. Results demonstrated that PC improved drought tolerance by enhancing antioxidant defense, retaining higher relative water content, survival percentages, and dry weight of cel s. In addition, PEPC activity in PC under PEG treatment was strengthened by addition of H2O2 inhibitor, dimethylthiourea （DMTU） and NO synthesis inhibitor, 2‐（4‐carboxyphenyl‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide （cPTIO）, respectively, while that in PC was weakened by addition of free calcium chelator, ethylene glycol‐bis（b‐aminoethylether）‐N,N,N0 ,N0‐tetraacetic acid （EGTA） t calcium channel outflow inhibitor, ruthenium red （RR） t plasma membrane channel blocker La（NO3）3, but EGTA t RR did not. Results also showed that NO and Ca2t was lying downstream of H2O2 in drought‐induced signaling. Calcium ion was also involved in the expression of C4‐pepc in PC. These results suggested that PC could improve oxidative tolerance in suspension‐cultured cel s and the acquisition of this tolerance required downregulation of H2O2 and the entry of extracel ular Ca2t into cel s across the plasma membrane for regulation of PEPC activity and C4‐pepc expression.

De novo assembly of a Chinese soybean genome

Soybean was domesticated in China and has become one of the most important oilseed crops. Due to bottlenecks in their introduction and dissemination, soybeans from different geographic areas exhibit extensive genetic diversity. Asia is the largest soybean market; therefore, a high-quality soybean reference genome from this area is critical for soybean research and breeding.Here, we report the de novo assembly and sequence analysis of a Chinese soybean genome for "Zhonghuang 13" by a combination of SMRT, Hi-C and optical mapping data. The assembled genome size is 1.025 Gb with a contig N50 of 3.46 Mb and a scaffold N50 of 51.87 Mb. Comparisons between this genome and the previously reported reference genome(cv. Williams82) uncovered more than 250,000 structure variations. A total of 52,051 protein coding genes and 36,429 transposable elements were annotated for this genome, and a gene co-expression network including 39,967 genes was also established. This high quality Chinese soybean genome and its sequence analysis will provide valuable information for soybean improvement in the future.