摘要：The eukaryotic genome is packaged into a complex nucleoprotein structure named chromatin, balancing the compactness of genome and the accessibility of regulatory proteins and RNA polymerases to DNA. The mechanisms of the regulation of chromatin dynamics include the post-translational modification of histones, alteration of nucleosome positions by chromatin remodelers, replacement of canonical histones by histone variants with the aid of histone chaperones, and dynamic organization of the three-dimensional genome in the small nucleus. Histone variants are different from canonical histones by substitution of several amino acid residues or changes in amino acid sequence. Histone variants perform specialized functions such as altering nucleosome stability, dynamics, structure, as well as playing critical roles in a range of biological processes like transcriptional regulation, DNA repair and recombination, development and immune responses. Here we discuss how histone variants, their modification and specific loading to chromatin are involved in transcriptional regulation, DNA repair and plant development.

摘要：Precision genome editing is highly desired for crop *** recently emerged CRISPR/Cas technology offers great potential applications in precision plant genome engineering.A prime editing(PE)approach combining a reverse transcriptase(RT)with a Cas9 nickase and a“priming”extended guide RNA(gRNA)has shown a high frequency for precise genome modification in mammalian cells and several plant ***,the applications of the PE approach in dicot plants are still limited and *** designed and tested prime editors for precision editing of a synthetic sequence in a transient assay and for desirable alleles of 10 loci in tomato by stable *** data obtained by targeted deep sequencing also revealed only low PE efficiencies in both the tobacco and tomato *** assessment of the activities of the PE components uncovered that the fusion of RT to Cas9 and the structure of PE gRNAs(pegRNAs)negatively affected the cleaving activity of the Cas9 *** self-complementarity between the primer binding sequences(PBSs)and spacer sequence might pose risks to the activity of the Cas9 ***,modifying the pegRNA sequences by shortening or introducing mismatches to the PBSs to reduce their melting temperatures did not enhance the PE efficiency at the MADS-box protein(SlMBP21),alcobaca(SlALC),and acetolactate synthase 1(SlALS1)*** data show challenges of the PE approach in tomato,indicating that a further improvement of the PE system for successful applications is demanded,such as the use of improved expression systems for enriching active PE complexes.

摘要：Human life intimately depends on plants for food,biomaterials,health,energy,and a sustainable *** plants have been genetically improved mostly through breeding,along with limited modification via genetic engineering,yet they are still not able to meet the ever-increasing needs,in terms of both quantity and quality,resulting from the rapid increase in world population and expected standards of living.A step change that may address these challenges would be to expand the potential of plants using biosystems design *** represents a shift in plant science research from relatively simple trial-and-error approaches to innovative strategies based on predictive models of biological *** biosystems design seeks to accelerate plant genetic improvement using genome editing and genetic circuit engineering or create novel plant systems through de novo synthesis of plant *** this perspective,we present a comprehensive roadmap of plant biosystems design covering theories,principles,and technical methods,along with potential applications in basic and applied plant biology *** highlight current challenges,future opportunities,and research priorities,along with a framework for international collaboration,towards rapid advancement of this emerging interdisciplinary area of ***,we discuss the importance of social responsibility in utilizing plant biosystems design and suggest strategies for improving public perception,trust,and acceptance.