查看更多>>摘要：Sweet potato(Ipomoea batatas[L.]Lam.)is a crucial staple and bioenergy crop.Its abiotic stress tolerance holds significant importance in fully utilizing marginal lands.Transcriptional processes regulate abiotic stress responses,yet the molecular regulatory mechanisms in sweet potato remain unclear.In this study,a NAC(NAM,ATAF1/2,and CUC2)transcription factor,IbNAC087,was identified,which is commonly upregulated in salt-and drought-tolerant germ-plasms.Overexpression of IbNAC087 increased salt and drought tolerance by increasing jas-monic acid(JA)accumulation and activating re-active oxygen species(ROS)scavenging,whereas silencing this gene resulted in opposite phenotypes.JA-rich IbNAC087-OE(over-expression)plants exhibited more stomatal clo-sure than wild-type(WT)and IbNAC087-Ri plants under NaCl,polyethylene glycol,and methyl jasmonate treatments.IbNAC087 functions as a nuclear transcriptional activator and directly ac-tivates the expression of the key JA biosynthesis-related genes lipoxygenase(IbLOX)and allene oxide synthase(IbAOS).Moreover,IbNAC087 physically interacted with a RING-type E3 ubiq-uitin ligase NAC087-INTERACTING E3 LIGASE(IbNIEL),negatively regulating salt and drought tolerance in sweet potato.IbNIEL ubiquitinated IbNAC087 to promote 26S proteasome degrada-tion,which weakened its activation on IbLOX and IbAOS.The findings provide insights into the mechanism underlying the IbNIEL-IbNAC087 module regulation of JA-dependent salt and drought response in sweet potato and provide candidate genes for improving abiotic stress tolerance in crops.
查看更多>>摘要：Rice(Oryza sativa)is a significant crop worldwide with a genome shaped by various evolutionary factors.Rice centromeres are crucial for chromo-some segregation,and contain some unreported genes.Due to the diverse and complex centromere region,a comprehensive understanding of rice centromere structure and function at the population level is needed.We constructed a high-quality centromere map based on the rice super pan-genome consisting of a 251-accession panel com-prising both cultivated and wild species of Asian and African rice.We showed that rice cen-tromeres have diverse satellite repeat CentO,which vary across chromosomes and subpopulations,reflecting their distinct evolutionary patterns.We also revealed that long terminal repeats(LTRs),especially young Gypsy-type LTRs,are abundant in the peripheral CentO-enriched regions and drive rice centromere expansion and evolution.Fur-thermore,high-quality genome assembly and com-plete telomere-to-telomere(T2T)reference genome enable us to obtain more centromeric genome in-formation despite mapping and cloning of cen-tromere genes being challenging.We investigated the association between structural variations and gene expression in the rice centromere.A centromere gene,OsMAB,which positively regu-lates rice tiller number,was further confirmed by expression quantitative trait loci,haplotype analysis and clustered regularly interspaced palindromic repeats(CRISPR)/CRISPR-associated protein 9 methods.By revealing the new insights into the evolutionary patterns and biological roles of rice centromeres,our finding will facilitate future research on centromere biology and crop improvement.
查看更多>>摘要：In plants,the genome structure of hybrids changes compared with their parents,but the effects of these changes in hybrids remain elusive.Comparing re-ciprocal crosses between Col×C24 and C24×Col in Arabidopsis using high-throughput chromosome conformation capture assay(Hi-C)analysis,we found that hybrid three-dimensional(3D)chromatin organ-ization had more long-distance interactions relative to parents,and this was mainly located in promoter regions and enriched in genes with heterosis-related pathways.The interactions between euchromatin and heterochromatin were increased,and the compartment strength decreased in hybrids.In compartment domain(CD)boundaries,the distal in-teractions were more in hybrids than their parents.In the hybrids of CURLY LEAF(clf)mutants clfCol×clfC24 and clfC24×clfCol,the heterosis phenotype was damaged,and the long-distance interactions in hy-brids were fewer than in their parents with lower H3K27me3.ChIP-seq data revealed higher levels of H3K27me3 in the region adjacent to the CD boun-dary and the same interactional homo-trans sites in the wild-type(WT)hybrids,which may have led to more long-distance interactions.In addition,the dif-ferentially expressed genes(DEGs)located in the boundaries of CDs and loop regions changed ob-viously in WT,and the functional enrichment for DEGs was different between WT and clf in the long-distance interactions and loop regions.Our findings may therefore propose a new epigenetic explanation of heterosis in the Arabidopsis hybrids and provide new insights into crop breeding and yield increase.
查看更多>>摘要：Fruit functions in seed protection and dispersal and belongs to many dry and fleshy types,yet their evolutionary pattern remains unclear in part due to uncertainties in the phylogenetic relationships among several orders and fami-lies.Thus we used nuclear genes of 502 an-giosperm species representing 231 families to reconstruct a well supported phylogeny,with resolved relationships for orders and families with previously uncertain placements.Using this phylogeny as a framework,molecular dating supports a Triassic origin of the crown angiosperms,followed by the emergence of most orders in the Jurassic and Cretaceous and their rise to ecological dominance during the Cretaceous Terrestrial Revolution.The ro-bust phylogeny allowed an examination of the evolutionary pattern of fruit and ovary types,revealing a trend of parallel carpel fusions during early diversifications in eudicots,mon-ocots,and magnoliids.Moreover,taxa in the same order or family with the same ovary type can develop either dry or fleshy fruits with strong correlations between specific types of dry and fleshy fruits;such associations of ovary,dry and fleshy fruits define several ovary-fruit"modules"each found in multiple families.One of the frequent modules has an ovary containing multiple ovules,capsules and ber-ries,and another with an ovary having one or two ovules,achenes(or other single-seeded dry fruits)and drupes.This new perspective of re-lationships among fruit types highlights the closeness of specific dry and fleshy fruit types,such as capsule and berry,that develop from the same ovary type and belong to the same module relative to dry and fleshy fruits of other modules(such as achenes and drupes).Further analyses of gene families containing known genes for ovary and fruit de-velopment identified phylogenetic nodes with multiple gene duplications,supporting a pos-sible role of whole-genome duplications,in combination with climate changes and animal behaviors,in angiosperm fruit and ovary diversification.
查看更多>>摘要：Rice is a staple food for half of the world's pop-ulation,but it is a poor dietary source of calcium(Ca)due to the low concentration.It is an important issue to boost Ca concentration in this grain to improve Ca deficiency risk,but the mechanisms underlying Ca accumulation are poorly understood.Here,we obtained a rice(Oryza sativa)mutant with high shoot Ca accumulation.The mutant exhibited 26%-53%higher Ca in shoots than did wild-type rice(WT)at different Ca supplies.Ca concentration in the xylem sap was 36%higher in the mutant than in the WT.There was no difference in agronomic traits between the WT and mutant,but the mutant showed 25%higher Ca in the polished grain com-pared with the WT.Map-based cloning combined with a complementation test revealed that the mutant phenotype was caused by an 18-bp dele-tion of a gene,OsK5.2,belonging to the Shaker-like K+ channel family.OsK5.2 was highly expressed in the mature region of the roots and its expression in the roots was not affected by Ca levels,but upre-gulated by low K.Immunostaining showed that OsK5.2 was mainly expressed in the pericycle of the roots.Taken together,our results revealed a novel role for OsK5.2 in Ca translocation in rice,and will be a good target for Ca biofortification in rice.
查看更多>>摘要：Anthocyanins are secondary metabolites induced by environmental stimuli and developmental signals.The positive regulators of anthocyanin biosynthesis have been reported,whereas the anthocyanin re-pressors have been neglected.Although the signal transduction pathways of gibberellin(GA)and jas-monic acid(JA)and their regulation of anthocyanin biosynthesis have been investigated,the cross-talk between GA and JA and the antagonistic mechanism of regulating anthocyanin biosynthesis remain to be investigated.In this study,we identified the antho-cyanin repressor MdbHLH162 in apple and revealed its molecular mechanism of regulating anthocyanin biosynthesis by integrating the GA and JA signals.MdbHLH162 exerted passive repression by inter-acting with MdbHLH3 and MdbHLH33,which are two recognized positive regulators of anthocyanin biosynthesis.MdbHLH162 negatively regulated an-thocyanin biosynthesis by disrupting the formation of the anthocyanin-activated MdMYB1-MdbHLH3/33 complexes and weakening transcriptional activation of the anthocyanin biosynthetic genes MdDFR and MdUF3GT by MdbHLH3 and MdbHLH33.The GA repressor MdRGL2a antagonized MdbHLH162-mediated inhibition of anthocyanins by sequestering MdbHLH162 from the MdbHLH162-MdbHLH3/33 complex.The JA repressors MdJAZ1 and MdJAZ2 interfered with the antagonistic regulation of MdbHLH162 by MdRGL2a by titrating the formation of the MdRGL2a-MdbHLH162 complex.Our findings reveal that MdbHLH162 integrates the GA and JA signals to negatively regulate anthocyanin biosyn-thesis.This study provides new information for dis-covering more anthocyanin biosynthesis repressors and explores the cross-talk between hormone signals.
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