查看更多>>摘要：Linalool and caryophyllene are the main monoterpene and sesquiterpene compounds in lavender;however,the genes regulating their biosynthesis still remain many unknowns.Here,we identified LaMYC7,a positive regulator of linalool and caryophyllene biosynthesis,confers plant resistance to Pseudomonas syringae.LaMYC7 was highly expressed in glandular trichomes,and LaMYC7 overexpression could significantly increase the linalool and caryophyllene contents and reduce susceptibility to P.syringae in Nicotiana.In addition,the linalool possessed antimicrobial activity against P.syringae growth and acted dose-dependently.Further analysis demonstrated that LaMYC7 directly bound to the promoter region of LaTPS76,which encodes the terpene synthase(TPS)for caryophyllene biosynthesis,and that LaTPS76 was highly expressed in glandular trichomes.Notably,the LaMYC7 promoter contained hormone and stress-responsive regulatory elements and responded to various treatments,including ultraviolet,low temperature,salt,drought,methyl jasmonate,and P.syringae infection treatments.Under these treatments,the changes in the linalool and caryophyllene contents were similar to those in LaMYC7 transcript abundance.Based on the results,LaMYC7 could respond to P.syringae infection in addition to being involved in linalool and caryophyllene biosynthesis.Thus,the MYC transcription factor gene LaMYC7 can be used in the breeding of high-yielding linalool and caryophyllene lavender varieties with pathogen resistance.
查看更多>>摘要：Long-distance transport or systemic silencing effects of exogenous biologically active RNA molecules in higher plants have not been reported.Here,we report that cationized bovine serum albumin(cBSA)avidly binds double-stranded beta-glucuronidase RNA(dsGUS RNA)to form nucleic acid-protein nanocomplexes.In our experiments with tobacco and poplar plants,we have successfully demonstrated systemic gene silencing effects of cBSA/dsGUS RNA nanocomplexes when we locally applied the nanocomplexes from the basal ends of leaf petioles or shoots.We have further demonstrated that the cBSA/dsGUS RNA nanocomplexes are highly effective in silencing both the conditionally inducible DR5-GUS gene and the constitutively active 35S-GUS gene in leaf,shoot,and shoot meristem tissues.This cBSA/dsRNA delivery technology may provide a convenient,fast,and inexpensive tool for characterizing gene functions in plants and potentially for in planta gene editing.
查看更多>>摘要：Tanshinones and phenolic acids are two major classes of bioactive compounds in Salvia miltiorrhiza.Revealing the regulatory mechanism of their biosynthesis is crucial for quality improvement of S.miltiorrhiza medicinal materials.Here we demonstrated that Smi-miR858a-Smi-miR858c,a miRNA family previously known to regulate flavonoid biosynthesis,also played critical regulatory roles in tanshinone and phenolic acid biosynthesis in S.miltiorrhiza.Overexpression of Smi-miR858a in S.miltiorrhiza plants caused significant growth retardation and tanshinone and phenolic acid reduction.Computational prediction and degradome and RNA-seq analyses revealed that Smi-miR858a could directly cleave the transcripts of SmMYB6,SmMYB97,SmMYB111,and SmMYB112.Yeast one-hybrid and transient transcriptional activity assays showed that Smi-miR858a-regulated SmMYBs,such as SmMYB6 and SmMYB112,could activate the expression of SmPAL1 and SmTAT1 involved in phenolic acid biosynthesis and SmCPS1 and SmKSL1 associated with tanshinone biosynthesis.In addition to directly activating the genes involved in bioactive compound biosynthesis pathways,SmMYB6,SmMYB97,and SmMYB112 could also activate SmAOC2,SmAOS4,and SmJMT2 involved in the biosynthesis of methyl jasmonate,a significant elicitor of plant secondary metabolism.The results suggest the existence of dual signaling pathways for the regulation of Smi-miR858a in bioactive compound biosynthesis in S.miltiorrhiza.
查看更多>>摘要：To identify the compounds that contribute to the diverse flavours of table grapes,the flavours and volatile compounds of 38 grape cultivars harvested over 3 years are evaluated through sensory analysis and solvent-assisted flavour evaporation(SAFE).The cultivars are characterized and grouped into seven clusters by hierarchical cluster analysis(HCA)using sensory evaluation data with a flavour wheel specific to table grapes.These clusters were similar to conventional flavour classifications,except that the foxy and neutral cultivars form multiple clusters,highlighting the flavour diversity of table grapes.The SAFE method provides a comprehensive profile of the volatile compounds,including slightly volatile compounds whose profiles are lacking in hybrid grapes and Vitis rotundifolia.The sensory evaluation is supported by the volatile compound profiles,and relationships between the datasets are clarified by multivariate analysis.Specific accumulations and combinations of compounds(α-pinene,β-pinene,phenylethyl alcohol,furaneol,mesifurane,methyl N-formylanthranilate,and mixed ethyl ester and monoterpenoid)were also identified that contribute to the diversity of flavours(fresh green,floral,fruity,fatty green,sweet,fermented/sour)in table grapes,including linalool and linalool analogues(muscat flavour)along with ethyl ester and hydroxyethyl esters(foxy flavour).The accumulation of these compounds was positively related to a higher flavour intensity.Their specific accumulation and combination supported the flavour diversity of table grapes.This study identified novel flavour-associated compound profiles in table grapes through in-depth volatile compound analysis and non-conventional multivariate analysis.
查看更多>>摘要：Grafting is a traditional and significant strategy to suppress soil-borne diseases,such as the crown gall disease caused by tumorigenic Agrobacterium and Rhizobium.Root exudates and the rhizosphere microbiome play critical roles in controlling crown gall disease,but their roles in suppressing crown gall disease in grafted plants remain unclear.Here,disease-susceptible cherry rootstock'Gisela 6'and disease-resistant cherry rootstock'Haiying 1'were grafted onto each other or self-grafted.The effect of their root exudates on the soil microbiome composition and the abundance of pathogenic Agrobacterium were studied.Grafting onto the disease-resistant rootstock helped to reduce the abundance of pathogenic Agrobacterium,accompanied by altering root exudation,enriching potential beneficial bacteria,and changing soil function.Then,the composition of the root exudates from grafted plants was analyzed and the potential compounds responsible for decreasing pathogenic Agrobacterium abundance were identified.Based on quantitative measurement of the concentrations of the compounds and testing the impacts of supplied pure chemicals on abundance and chemotaxis of pathogenic Agrobacterium and potential beneficial bacteria,the decreased valine in root exudates of the plant grafted onto resistant rootstock was found to contribute to decreasing Agrobacterium abundance,enriching some potential beneficial bacteria and suppressing crown gall disease.This study provides insights into the mechanism whereby grafted plants suppress soil-borne disease.
查看更多>>摘要：A Cucurbita pepo mutant with multiple defects in growth and development has been identified and characterized.The mutant dwfcp displayed a dwarf phenotype with dark green and shrinking leaves,shortened internodes and petioles,shorter but thicker roots and greater root biomass,and reduced fertility.The causal mutation of the phenotype was found to disrupt gene Cp4.1LG17g04540,the squash orthologue of the Arabidopsis brassinosteroid(BR)biosynthesis gene DWF5,encoding for 7-dehydrocholesterol reductase.A single nucleotide transition(G＞A)causes a splicing defect in intron 6 that leads to a premature stop codon and a truncated CpDWF5 protein.The mutation co-segregated with the dwarf phenotype in a large BC1S1 segregating population.The reduced expression of CpDWF5 and brassinolide(BL)content in most mutant organs,and partial rescue of the mutant phenotype by exogenous application of BL,showed that the primary cause of the dwarfism in dwfcp is a BR deficiency.The results showed that in C.pepo,CpDWF5 is not only a positive growth regulator of different plant organs but also a negative regulator of salt tolerance.During germination and the early stages of seedling development,the dwarf mutant was less affected by salt stress than the wild type,concomitantly with a greater upregulation of genes associated with salt tolerance,including those involved in abscisic acid(ABA)biosynthesis,ABA and Ca2+signaling,and those coding for cation exchangers and transporters.
查看更多>>摘要：Apple rootstock dwarfing and dense planting are common practices in apple farming.However,the dwarfing mechanisms are not understood.In our study,the expression of MdARF3 in the root system of dwarfing rootstock'M9'was lower than in the vigorous rootstock from Malus micromalus due to the deletion of the WUSATAg element in the promoter of the'M9'genotype.Notably,this deletion variation was significantly associated with dwarfing rootstocks.Subsequently,transgenic tobacco(Nicotiana tabacum)cv.Xanthi was generated with the ARF3 promoter from'M9'and M.micromalus genotypes.The transgenic apple with 35S::MdARF3 was also obtained.The transgenic tobacco and apple with the highly expressed ARF3 had a longer root system and a higher plant height phenotype.Furthermore,the yeast one-hybrid,luciferase,electrophoretic mobility shift assays,and Chip-qPCR identified MdWOX4-1 in apples that interacted with the pMm-ARF3 promoter but not the pM9-ARF3 promoter.Notably,MdWOX4-1 significantly increased the transcriptional activity of MdARF3 and MdLBD16-2.However,MdARF3 significantly decreased the transcriptional activity of MdLBD16-2.Further analysis revealed that MdARF3 and MdLBD16-2 were temporally expressed during different stages of lateral root development.pMdLBD16-2 was mainly expressed during the early stage of lateral root development,which promoted lateral root production.On the contrary,pMmARF3 was expressed during the late stage of lateral root development to promote elongation.The findings in our study will shed light on the genetic causes of apple plant dwarfism and provide strategies for molecular breeding of dwarfing apple rootstocks.
查看更多>>摘要：Bud endodormancy in perennial plants is a sophisticated system that adapts to seasonal climatic changes.Growth-promoting signals such as low temperature and gibberellins(GAs)are crucial for facilitating budbreak following endodormancy release(EDR).However,the regulatory mechanisms underlying GA-mediated budbreak in tree peony(Paeonia suffruticosa)remain unclear.In tree peony,the expression of PsmiR159b among three differentially expressed miR159 members was inhibited with the prolonged chilling,and overexpression of PsMIR159b delayed budbreak,whereas silencing PsmiR159b promoted budbreak after dormancy.PsMYB65,a downstream transcription factor in the GA pathway,was induced by prolonged chilling and exogenous GA3 treatments.PsMYB65 was identified as a target of PsmiR159b,and promoted budbreak in tree peony.RNA-seq of PsMYB65-slienced buds revealed significant enrichment in the GO terms regulation of'cell cycle'and'DNA replication'among differentially expressed genes.Yeast one-hybrid and electrophoretic mobility shift assays demonstrated that PsMYB65 directly bound to the promoter of the type-D cyclin gene PsCYCD3;1.Dual-luciferase reporter assay indicated that PsMYB65 positively regulate PsCYCD3;1 expression,suggesting that miR159b-PsMYB65 module contributes to budbreak by influencing the cell cycle.Our findings revealed that the PsmiR159b-PsMYB65 module functioned in budbreak after dormancy by regulating cell proliferation,providing valuable insights into the endodormancy release regulation mechanism.
查看更多>>摘要：Texture softening is a physiological indicator of fruit ripening,which eventually contributes to fruit quality and the consumer's accep-tance.Despite great progress having been made in identification of the genes related to fruit softening,the upstream transcriptional regulatory pathways of these softening-related genes are not fully elucidated.Here,a novel bHLH gene,designated as MabHLH28,was identified because of its significant upregulation in banana fruit ripening.DAP-Seq analysis revealed that MabHLH28 bound to the core sequence of'CAYGTG'presented in promoter regions of fruit softening-associated genes,such as the genes related to cell wall modification(MaPG3,MaPE1,MaPL5,MaPL8,MaEXP1,MaEXP2,MaEXPA2,and MaEXPA15)and starch degradation(MaGWD1 and MaLSF2),and these bindings were validated by EMSA and DLR assays.Transient overexpression and knockdown of MabHLH28 in banana fruit resulted in up-and down-regulation of softening-related genes,thereby hastening and postponing fruit ripening.Furthermore,overexpression of MabHLH28 in tomato accelerated the ripening process by elevating the accumulation of softening-associated genes.In addition,MabHLH28 showed interaction withMaWRKY49/111 and itself to form protein complexes,which could combinatorically strengthen the transcription of softening-associated genes.Taken together,our findings suggest that MabHLH28 mediates fruit softening by upregulating the expression of softening-related genes either alone or in combination with MaWRKY49/111.
查看更多>>摘要：Lily bulbils,which serve as advantageous axillary organs for vegetative propagation,have not been extensively studied in terms of the mechanism of bulbil initiation.The functions of auxin and sucrose metabolism have been implicated in axillary organ development,but their relationship in regulating bulbil initiation remains unclear.In this study,exogenous indole-3-acetic acid(IAA)treatment increased the endogenous auxin levels at leaf axils and significantly decreased bulbil number,whereas treatment with the auxin polar transport inhibitor N-1-naphthylphthalamic acid(NPA),which resulted in a low auxin concentration at leaf axils,stimulated bulbil initiation and increased bulbil number.A low level of auxin caused by NPA spraying or silencing of auxin biosynthesis genes YUCCA FLAVIN MONOOXYGENASE-LIKE 6(LlYUC6)and TRYPTOPHAN AMINOTRANSFERASE RELATED 1(LlTAR1)facilitated sucrose metabolism by activating the expression of SUCROSE SYNTHASES 1(LlSusy1)and CELL WALL INVERTASE 2(LlCWIN2),resulting in enhanced bulbil initiation.Silencing LlSusy1 or LlCWIN2 hindered bulbil initiation.Moreover,the transcription factor BASIC HELIX-LOOP-HELIX 35(LlbHLH35)directly bound the promoter of LlSusy1,but not the promoter of LlCWIN2,and activated its transcription in response to the auxin content,bridging the gap between auxin and sucrose metabolism.In conclusion,our results reveal that an LlbHLH35-LlSusy1 module mediates auxin-regulated sucrose metabolism during bulbil initiation.
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