Effects of water deficit and high N fertilization on wheat storage protein synthesis,gluten secondary structure,and breadmaking quality

The content and composition of wheat storage proteins are the major determinants of dough rheological properties and breadmaking quality and are influenced by cultivation conditions.This study aimed to investigate the effects of water deficit and high N-fertilizer application on wheat storage protein synthesis,gluten secondary structure,and breadmaking quality.Reverse-phase ultrahigh-performance liquid chromatography analysis showed that storage protein and gluten macropolymer accumulation was promoted under both independent applications and a combination of water-deficit and high N-fertilizer treatments.Fourier-transform infrared spectroscopy showed that water deficit and high N-fertilizer treatments generally improved protein secondary structure formation and lipid accumulation,and reduced flour moisture.In particular,high N-fertilizer application increasedβ-sheet content by 10.4%and the combination of water-deficit and high N-fertilizer treatments increased random coil content by 7.6%.These changes in gluten content and secondary structure led to improved dough rheological properties and breadmaking quality,including superior loaf internal structure,volume,and score.Our results demonstrate that moderately high N-fertilizer application under drought conditions can improve gluten accumulation,gluten secondary structure formation,and baking quality.

Generation of a series of mutant lines resistant to imidazolinone by screening an EMS-based mutant library in common wheat

The breeding of herbicide-resistant wheat varieties has helped control weeds in wheat fields economically and effectively.Imidazolinone (IMI) herbicides are popular as they have low toxicity in mammals,are effective at small doses,and exhibit broad-spectrum herbicidal action in the field.Therefore,the isolation and genetic and molecular characterization of IMI-resistant wheat mutants will enhance weed management in wheat fields.In the present study,352 IMI-resistant plants were isolated by genetic screening from a mutant pool prepared by EMS-based random mutagenesis.Cloning of the mutated genes from the IMI-resistant plants indicated that ten taals alleles had been isolated,and mutation in one of three Ta ALS homolog genes conferred IMI resistance,and such a mutation is a dominant trait.Further analysis showed that taals-d exhibited the greatest IMI resistance,whereas taals-b exhibited the weakest resistance to IMI among three homologous taals mutants.In terms of IMI resistance,the taals triple mutant was stronger than the taals double mutants,and the taals double mutants were stronger than the single mutants,indicating a dose-dependent effect of the Ta ALS mutation on IMI resistance in wheat.Biochemical analysis indicated that the mutation in Ta ALS increased the tolerance of Ta ALS to inhibition by IMI.Our work details the genetic and molecular characterization of als wheat mutants,provides a foundation for understanding IMI resistance and breeding wheat varieties with herbicide resistance,and indicates that genetic screening using a mutagenized pool is an effective and important means of breeding crops with additional desired agricultural traits.

Current strategies and advances in wheat biology

The characterization of agronomically important genes has great potential for the improvement of wheat.However,progress in wheat genetics and functional genomics has been impeded by the high complexity and enormous size of the wheat genome.Recent advances in genome sequencing and sequence assembly have produced a high-quality genome sequence for wheat.Here,we suggest that the strategies used to characterize biological mechanisms in model species,including mutant preparation and characterization,gene cloning methods,and improved transgenic technology,can be applied to wheat biology.These strategies will accelerate progress in wheat biology and promote wheat breeding program development.We also outline recent advances in wheat functional genomics.Finally,we discuss the future of wheat functional genomics and the rational design-based molecular breeding of new wheat varieties to contribute to world food security.

A functional characterization of TaMs1 orthologs in Poaceae plants

TaMs1 encodes a non-specific lipid transfer protein(nsLTP) and is required for pollen development in wheat. Although MS1 is a Poaceae-specific gene, the roles of MS1 genes in other Poaceae plants are unknown, especially in rice and maize. Here, we identified one ortholog in rice(OsLTPg29) and two orthologs in maize(ZmLTPg11 and ZmLTPx2). Similar to TaMs1, both OsLTPg29 and ZmLTPg11 genes are specifically expressed in the microsporocytes, and both OsLTPg29 and ZmLTPg11 proteins showed lipid-binding ability to phosphatidic acid and several phosphoinositides. To determine their roles in pollen development, we created osltpg29 mutants and zmltpg11 zmltpx2 double mutants by CRISPR/Cas9.osltpg29, not zmltpg11 zmltpx2, is defective in pollen development, and only OsLTPg29, not ZmLTPg11,can rescue the male sterility of tams1 mutant. Our results demonstrate that the biological function of MS1 in pollen development differs in the evolution of Poaceae plants.

Phylogeny and taxonomy of Rhytisma‑like species worldwide

Rhytisma Fr.is the type genus of Rhytismataceae(Rhytismatales,Leotiomycetes,Ascomycota).Rhytisma-like species include members of Cryptomyces,Rhytisma and Vladracula.They are parasites on leaves of broadleaf trees and cause tar spot diseases.In this study,a phylogeny based on the large subunit of the ribosomal rRNA gene(nrLSU)and the mitochondrial small subunit(mtSSU)is presented,including sequences of 39 newly collected specimens from East Asia,Europe,and temperate as well as tropical America.Based on analyses of morphology,phylogeny as well as host-specificity and diversification time estimates,the family Rhytismataceae sensu stricto is proposed,and eight genera are accepted in this narrow family,including four novel genera(Densorhytisma,Fanglania,Johnstoniella and Shiqia),the type genus Rhytisma,and the reinstated genera Lophodermina,Placuntium and Xyloma.Lophodermina clusters within the main Rhytisma clade in our analyses,but is divergent in morphological terms,not having large compound stromata.Thirty species are recognized,including seven novel species(Fanglania hubeiensis,F.parasitica,Johnstoniella yunnanensis,Rhytisma japonicum,Rh.taiwanense,Xyloma globosum,and X.shennongjiaense),fifteen new combinations(Densorhytisma anhuiense,D.huangshanense,F.concova,F.himalensis,F.ilicis-integrae,F.ilicis-latifoliae,F.ilicis-pedunculosae,J.lonicerae,Rh.annuliforme,Shiqia menziesii,S.yuexiensis,X.filamentosum,X.maximum,X.muelleri,and X.polare),one new name(J.xylostei),seven known species(Lophodermina melaleuca,Placuntium andromedae,Rhytisma acerinum,Rh.americanum,Rh.punctatum,X.salicinum,and X.umbonatum).In addition,seven immature specimens were studied but not assigned to existing species,herein referred to as Fanglania sp.1,Johnstoniella sp.1,Johnstoniella sp.2,Placuntium sp.1,Placuntium sp.2,Rhytisma sp.1,and Xyloma sp.1.The systematic positions of Cryptomyces maximus,Cr.muelleri and Vladracula annuliformis are re-assigned based on phylogenetic analysis.One Rhytisma-like species from tropical America was segregated from Rhytismataceae s.str.,thus a novel genus Neorhytisma was established to accommodate this species,with the one new combinations Neorhytisma panamense.The results of the molecular phylogenetic analysis indicate that Rhytisma-like species are host-specific at genus level.Apparently,Rhytisma-like species coevolved with their hosts,and Rhytisma-like species on Ericaceae seem to be in the process of host jumping.Morphological characteristics of ascomata are important for the delimitation of species and genera of Rhytisma-like species.This study provides a key to genera and species of recognized Rhytisma-like species worldwide.

A molecular framework for signaling crosstalk between jasmonate and ethylene in anthocyanin biosynthesis,trichome development,and defenses against insect herbivores in Arabidopsis

The phytohormones ethylene(ET)and jasmonate(JA)regulate plant development,growth,and defense responses;however,the molecular basis for their signaling crosstalk is unclear.Here,we show that JA-ZIM-domain(JAZ)proteins,which repress JA signaling,repress trichome initiation/branching and anthocyanin accumulation,and inhibit the transcriptional activity of the basic helix-loop-helix(bHLH)-MYBmembers(GLABRA3(GL3)-GL1 and TRANSPARENT TESTA 8(TT8)-MYB75)of WD-repeat/bHLH/MYB(WBM)complexes.The ET-stabilized transcription factors ETHYLENEINSENSITIVE3(EIN3)and EIN3-LIKE1(EIL1)were found to bind to several members of WBM complexes,including GL3,ENHANCER OF GLABRA3(EGL3),TT8,GL1,MYB75,and TRANSPARENT TESTA GLABRA1(TTG1).This binding repressed the transcriptional activity of the b HLH-MYB proteins and inhibited anthocyanin accumulation,trichome formation,and defenses against insect herbivores while promoting root hair formation.Conversely,the JA-activated b HLH members GL3,EGL3,and TT8 of WBM complexes were able to interact with and attenuate the transcriptional activity of EIN3/EIL1 at the HOOKLESS1 promoter,and their overexpression inhibited apical hook formation.Thus,this study demonstrates a molecular framework for signaling crosstalk between JA and ET in plant development,secondary metabolism,and defense responses.

MicroProteins:Dynamic and accurate regulation of protein activity

Proteins usually assemble oligomers or high-order complexes to increase their efficiency and specificity in biological processes.The dynamic equilibrium of complex formation and disruption imposes reversible regulation of protein function.MicroProteins are small,single-domain proteins that directly bind target protein complexes and disrupt their assembly.Growing evidence shows that microProteins are efficient regulators of protein activity at the post-translational level.In the last few decades,thousands of plant microProteins have been predicted by computational approaches,but only a few have been experimentally validated.Recent studies highlighted the mechanistic working modes of newly-identified microProteins in Arabidopsis and other plant species.Here,we review characterized microProteins,including their biological roles,regulatory targets,and modes of action.In particular,we focus on microProtein-directed allosteric modulation of key components in light signaling pathways,and we summarize the biogenesis and evolutionary trajectory of known microProteins in plants.Understanding the regulatory mechanisms of microProteins is an important step towards potential utilization of microProteins as versatile biotechnological tools in crop bioengineering.

CRISPR/Cas9-mediated disruption of TaNP1 genes results in complete male sterility in bread wheat

Male sterile genes and mutants are valuable resources in hybrid seed production for monoclinous crops.High genetic redundancy due to allohexaploidy makes it difficult to obtain the nuclear recessive male sterile mutants through spontaneous mutation or chemical or physical mutagenesis methods in wheat.The emerging effective genome editing tool,CRISPR/Cas9 system,makes it possible to achieve simultaneous mutagenesis in multiple homoeoalleles.To improve the genome modification efficiency of the CRISPR/Cas9 system in wheat,we compared four different RNA polymerase(Pol)Ⅲpromoters(TaU3 p,TaU6 p,OsU3 p,and OsU6 p)and three types of sgRNA scaffold in the protoplast system.We show that the TaU3 promoter-driven optimized sgRNA scaffold was most effective.The optimized CRISPR/Cas9 system was used to edit three TaNP1 homoeoalleles,whose orthologs,OsNP1 in rice and ZmIPE1 in maize,encode a putative glucose-methanol-choline oxidoreductase and are required for male sterility.Triple homozygous mutations in TaNP1 genes result in complete male sterility.We further demonstrated that anyone wild-type copy of the three TaNP1 genes is sufficient for maintenance of male fertility.Taken together,this study provides an optimized CRISPR/Cas9 vector for wheat genome editing and a complete male sterile mutant for development of a commercially viable hybrid wheat seed production system.

A chloride efflux transporter,BIG RICE GRAIN 1,is involved in mediating grain size and salt tolerance in rice

Grain size is determined by the size and number of cells in the grain.The regulation of grain size is crucial for improving crop yield;however,the genes and molecular mechanisms that control grain size remain elusive.Here,we report that a member of the detoxification efflux carrier/Multidrug and Toxic Compound Extrusion(DTX/MATE)family transporters,BIG RICE GRAIN 1(BIRG1),negatively influences grain size in rice(Oryza sativa L.).BIRG1 is highly expressed in reproductive organs and roots.In birg1 grain,the outer parenchyma layer cells of spikelet hulls are larger than in wild-type(WT)grains,but the cell number is unaltered.When expressed in Xenopus laevis oocytes,BIRG1 exhibits chloride efflux activity.Consistent with this role of BIRG1,the birg1 mutant shows reduced tolerance to salt stress at a toxic chloride level.Moreover,grains from birg1 plants contain a higher level of chloride than those of WT plants when grown under normal paddy field conditions,and the roots of birg1 accumulate more chloride than those of WT under saline conditions.Collectively,the data suggest that BIRG1 in rice functions as a chloride efflux transporter that is involved in mediating grain size and salt tolerance by controlling chloride homeostasis.

The CRISPR/Cas9 revolution continues: From base editing to prime editing in plant science

The ability to precisely inactivate or modify genes in model organisms helps us understand the mysteries of life. Clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9(Cas9), a revolutionary technology that could generate targeted mutants, has facilitated notable advances in plant science. Genome editing with CRISPR/Cas9 has gained great popularity and enabled several technical breakthroughs. Herein, we briefly introduce the CRISPR/Cas9, with a focus on the latest breakthroughs in precise genome editing(e.g., base editing and prime editing), and we summarize various platforms that developed to increase the editing efficiency, expand the targeting scope, and improve the specificity of base editing in plants. In addition, we emphasize the recent applications of these technologies to plants. Finally, we predict that CRISPR/Cas9 and CRISPR/Cas9-based genome editing will continue to revolutionize plant science and provide technical support for sustainable agricultural development.

The Arabidopsis AGAMOUS 5′-UTR represses downstream gene translation

Dear Editor,In eukaryotes, mature m RNAs have a tripartite structure consisting of a 5′-untranslated region(5′-UTR), a coding region and a 3′-untranslated region(3′-UTR). Though the coding region encodes the protein sequence.

Arabidopsis ENOR3 regulates RNAi-mediated antiviral defense

Viruses can infect host plants to cause severe diseases and substantial agricultural loss, while plants have evolved RNA interference （RNAi） strategy to defend against viral infection. Despite enormous efforts, only a few host proteins in RNAi pathway were shown to mediate antiviral defense, including RNA-dependent RNA polymerase I （RDRI）, RDR6, DICER-LIKE 2 （DCL2） and DCL4. In this study, we carried out a genetic screen for antiviral factors of RNAi pathway in Arabidopsis rdr6 background via inoculation with a 2b- deficient Cucumber Mosaic Virus （CMV-△2b）. We identified a mutant susceptible to CMV-△2h, referred to as enhancer o ojrdr6 （enor） 3-1 rdr6, and found that ENOR3 encodes a functionally unknown protein with high homology to the mammalian Non Imprinted in Prader-Willi/Angelman （NIPA） magnesium transporters. ENOR3 inhibits accumulation of CMV-△2b and acts additively with RDR1, RDR6, DCL2 and DCL4 in antivira/ defense. These results uncover that ENOR3 is a key component in antiviral RNAi Dathwav, and provide new insights into antiviral immunity.