查看更多>>摘要：ChinaMu is the largest sequence-indexed Mutator(Mu)transposon insertional library in maize(Zea mays).In this study,we made significant im-provements 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 re-covered 1/3 more germinal insertions,while re-quiring 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 el-ement and was used as the pollen donor for the mutation population.Using the Mu-starter ge-nome,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 im-proved the assignment of 117,689(54.5％)ger-minal 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 ge-nomes,including 23,006(80.4％)core genes shared by the two genomes.As a test model,we investigated Mu insertions in the pentatricopep-tide repeat(PPR)superfamily,discovering in-sertions for 92％(449/487)of PPR genes in Chi-naMu,demonstrating the usefulness of ChinaMu as a functional genomics resource for maize.
查看更多>>摘要：Due to its tropical origins,rice(Oryza sativa)is susceptible to cold stress,which poses severe threats to production.OsNAC5,a NAC-type tran-scription factor,participates in the cold stress re-sponse of rice,but the detailed mechanisms remain poorly understood.Here,we demonstrate that OsNAC5 positively regulates cold tolerance at ger-mination and in seedlings by directly activating the expression of ABSCISIC ACID INSENSITIVE 5(OsABI5).Haplotype analysis indicated that single nucleotide polymorphisms in a NAC-binding site in the OsABI5 promoter are strongly associated with cold tolerance.OsNAC5 also enhanced OsABI5 stability,thus regulating the expression of cold-responsive(COR)genes,enabling fine-tuned control of OsABI5 action for rapid,precise plant responses to cold stress.DNA affinity purification sequencing coupled with transcriptome deep sequencing identified several OsABI5 target genes involved in COR expression,including DEHYDRATION-RESPONSIVE ELEMENT BINDING FACTOR 1A(OsDREB1A),OsMYB20,and PEROX-IDASE 70(OsPRX70).In vivo and in vitro analyses suggested that OsABI5 positively regulates COR gene transcription,with marked COR upregulation in OsNAC5-overexpressing lines and down-regulation in osnac5 and/or osabi5 knockout mu-tants.This study extends our understanding of cold tolerance regulation via OsNAC5 through the OsABI5-CORs transcription module,which may be used to ameliorate cold tolerance in rice via ad-vanced breeding.
查看更多>>摘要：Drought is a major threat to alfalfa(Medicago sativa L.)production.The discovery of important alfalfa genes regulating drought response will facilitate breeding for drought-resistant alfalfa cultivars.Here,we report a genome-wide association study of drought resistance in alfalfa.We identified and functionally characterized an MYB-like tran-scription factor gene(MsMYBH),which increases the drought resistance in alfalfa.Compared with the wild-types,the biomass and forage quality were enhanced in MsMYBH overexpressed plants.Combined RNA-seq,proteomics and chromatin immunoprecipitation analysis showed that MsMYBH can directly bind to the promoters of MsMCP1,MsMCP2,MsPRX1A and MsCARCAB to improve their expression.The outcomes of such interactions include better water balance,high photosynthetic efficiency and scavenge excess H2O2 in response to drought.Furthermore,an E3 ubiquitin ligase(MsWAV3)was found to induce MsMYBH degrada-tion under long-term drought,via the 26S protea-some pathway.Furthermore,variable-number tandem repeats in MsMYBH promoter were char-acterized among a collection of germplasms,and the variation is associated with promoter activity.Collectively,our findings shed light on the functions of MsMYBH and provide a pivotal gene that could be leveraged for breeding drought-resistant alfalfa.This discovery also offers new insights into the mechanisms of drought resistance in alfalfa.
查看更多>>摘要：The high-affinity potassium transporters(HKTs),selectively permeable to either Na+alone or Na+/K+,play pivotal roles in maintaining plant Na+/K+homeostasis.Although their involvement in salt tolerance is widely reported,the molec-ular underpinnings of Oryza sativa HKTs remain elusive.In this study,we elucidate the structures of OsHKT1;1 and OsHKT2;1,representing two distinct classes of rice HKTs.The dimeric as-sembled OsHKTs can be structurally divided into four domains.At the dimer interface,a half-helix or a loop in the third domain is coordinated by the C-terminal region of the opposite subunit.Additionally,we present the structures of OsHKT1;5 salt-tolerant and salt-sensitive var-iants,a key quantitative trait locus associated with salt tolerance.The salt-tolerant variant of OsHKT1;5 exhibits enhanced Na+transport capability and displays a more flexible con-formation.These findings shed light on the mo-lecular basis of rice HKTs and provide insights into their role in salt tolerance.
查看更多>>摘要：Hybrid rice(Oryza sativa)generally outperforms its inbred parents in yield and stress tolerance,a phenomenon termed heterosis,but the underlying mechanism is not completely understood.Here,we combined transcriptome,proteome,physio-logical,and heterosis analyses to examine the salt response of super hybrid rice Chaoyou1000(CY1000).In addition to surpassing the mean values for its two parents(mid-parent heterosis),CY1000 exhibited a higher reactive oxygen spe-cies scavenging ability than both its parents(over-parent heterosis or heterobeltiosis).Nonadditive expression and allele-specific gene expression assays showed that the glutathione S-transferase gene OsGSTU26 and the amino acid transporter gene OsAAT30 may have major roles in heterosis for salt tolerance,acting in an overdominant fashion in CY1000.Furthermore,we identified OsWRKY72 as a common transcription factor that binds and regulates OsGSTU26 and OsAAT30.The salt-sensitive phenotypes were associated with the OsWRKY72paternal genotype or the OsAAT30maternal genotype in core rice germplasm varieties.OsWRKY72paternal specifically repressed the expression of OsGSTU26 under salt stress,leading to salinity sensitivity,while OsWRKY72-maternal specifically repressed OsAAT30,resulting in salinity tolerance.These results suggest that the OsWRKY72-OsAAT30/OsGSTU26 module may play an important role in heterosis for salt tolerance in an overdominant fashion in CY1000 hybrid rice,providing valuable clues to elucidate the mechanism of heterosis for salinity tolerance in hybrid rice.
查看更多>>摘要：Soil salinity has a major impact on rice seed germination,severely limiting rice production.Herein,a rice germination defective mutant under salt stress(gdss)was identified by using chemical mutagenesis.The GDSS gene was detected via MutMap and shown to encode potassium transporter OsHAK9.Phenotypic analysis of complementation and mutant lines demonstrated that OsHAK9 was an essential regulator responsible for seed germination under salt stress.OsHAK9 is highly expressed in germinating seed embryos.Ion contents and non-invasive micro-test technology results showed that OsHAK9 restricted K+efflux in salt-exposed germinating seeds for the balance of K+/Na+.Disruption of OsHAK9 significantly re-duced gibberellin 4(GA4)levels,and the ger-mination defective phenotype of oshak9a was partly rescued by exogenous GA3 treatment under salt stress.RNA sequencing(RNA-seq)and real-time quantitative polymerase chain reaction analysis demonstrated that the dis-ruption of OsHAK9 improved the GA-deactivated gene OsGA2ox7 expression in germinating seeds under salt stress,and the expression of OsGA2ox7 was significantly in-hibited by salt stress.Null mutants of Os-GA2ox7 created using clustered,regularly in-terspaced,short palindromic repeat(CRISPR)/CRISPR-associated nuclease 9 approach dis-played a dramatically increased seed germina-tion ability under salt stress.Overall,our results highlight that OsHAK9 regulates seed germi-nation performance under salt stress involving preventing GA degradation by mediating Os-GA2ox7,which provides a novel clue about the relationship between GA and OsHAKs in rice.
查看更多>>摘要：Auxin regulates flower and fruit abscission,but how developmental signals mediate auxin transport in abscission remains unclear.Here,we reveal the role of the transcription factor BEL1-LIKE HOMEO-DOMAIN11(SIBEL11)in regulating auxin transport during abscission in tomato(Solanum lyco-persicum).SIBEL11 is highly expressed in the fruit abscission zone,and its expression increases during fruit development.Knockdown of SIBEL11 expression by RNA interference(RNAi)caused premature fruit drop at the breaker(Br)and 3 d post-breaker(Br+3)stages of fruit development.Tran-scriptome and metabolome analysis of SIBEL11-RNAi lines revealed impaired flavonoid biosynthesis and decreased levels of most flavonoids,especially quercetin,which functions as an auxin transport inhibitor.This suggested that SIBEL11 prevents premature fruit abscission by modulating auxin ef-flux from fruits,which is crucial for the formation of an auxin response gradient.Indeed,quercetin treatment suppressed premature fruit drop in SIBEL11-RNAi plants.DNA affinity purification se-quencing(DAP-seq)analysis indicated that SIBEL11 induced expression of the transcription factor gene SIMYB111 by directly binding to its promoter.Chromatin immunoprecipitation-quantitative poly-merase chain reaction and electrophoretic mobility shift assay showed that S.lycopersicum MYELO-BLASTOSIS VIRAL ONCOGENE HOMOLOG111(SIMYB111)induces the expression of the core fla-vonoid biosynthesis genes SICHS1,SICHI,SIF3H,and SIFLS by directly binding to their promoters.Our findings suggest that the SIBEL11-SIMYB111 module modulates flavonoid biosynthesis to fine-tune auxin efflux from fruits and thus maintain an auxin response gradient in the pedicel,thereby preventing premature fruit drop.
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