Summary Adenine base editors (ABEs), which are generally engineered adenosine deaminases and Cas variants, introduce site‐specific A‐to‐G mutations for agronomic trait improvement. However, notably varying editing efficiencies, restrictive requirements for protospacer‐adjacent motifs (PAMs) and a narrow editing window greatly limit their application. Here, we developed a robust high‐efficiency ABE (PhieABE) toolbox for plants by fusing an evolved, highly active form of the adenosine deaminase TadA8e and a single‐stranded DNA‐binding domain (DBD), based on PAM‐less/free Streptococcus pyogenes Cas9 (SpCas9) nickase variants that recognize the PAM NGN (for SpCas9n‐NG and SpGn) or NNN (for SpRYn). By targeting 29 representative targets in rice and assessing the results, we demonstrate that PhieABEs have significantly improved base‐editing activity, expanded target range and broader editing windows compared to the ABE7.10 and general ABE8e systems. Among these PhieABEs, hyper ABE8e‐DBD‐SpRYn (hyABE8e‐SpRY) showed nearly 100% editing efficiency at some tested sites, with a high proportion of homozygous base substitutions in the editing windows and no single guide RNA (sgRNA)‐dependent off‐target changes. The original sgRNA was more compatible with PhieABEs than the evolved sgRNA. In conclusion, the DBD fusion effectively promotes base‐editing efficiency, and this novel PhieABE toolbox should have wide applications in plant functional genomics and crop improvement.

Dickeya zeae is a globally important pathogenic bacterium that infects a number of crops, including rice, maize, potato, and banana. Bacterial foot rot of rice caused by D. zeae is one of the most important bacterial diseases of rice in China and some Southeast Asian countries. To investigate the functions of integration host factor (IHF) in D. zeae, we generated knockout mutants of ihfA and ihfB. Phenotypic assays showed that both the ΔihfA and ΔihfB strains had greatly reduced mobility, biofilm formation, extracellular protease and pectinase activities, and toxin production compared with the wild-type strain. In addition, the mutants did not inhibit the germination of rice seeds, failed to cause soft rot in potatoes and a hypersensitive response in tobacco, and were avirulent in rice. Quantitative reverse-transcription polymerase chain reaction analysis demonstrated that IHF positively regulates the expression of zmsA, hrpN/Y, pelA/B/C, pehX, celZ, prtG, fliC, and DGC. Electrophoretic mobility shift assays further confirmed that IhfA binds to the promoter region of the diguanylate cyclase gene and alters the levels of a second bacterial messenger, c-di-GMP, to regulate the pathogenicity or other physiological functions of D. zeae. In summary, IHF is an important integrated regulator of pathogenicity in D. zeae.

Functional genomics, synthetic biology and metabolic engineering require efficient tools to deliver long DNA fragments or multiple gene constructs. Although numerous DNA assembly methods exist, most are complicated, time-consuming and expensive. Here, we developed a simple and flexible strategy, unique nucleotide sequence-guided nicking endonuclease (UNiE)mediated DNA assembly (UNiEDA), for efficient cloning of long DNAs and multigene stacking. In this system, a set of unique 15-nt 3 0 single-strand overhangs were designed and produced by nicking endonucleases (nickases) in vectors and insert sequences. We introduced UNiEDA into our modified Cre/loxP recombination-mediated TransGene Stacking II (TGSII) system to generate an improved multigene stacking system we call TGSII-UNiE. Using TGSII-UNiE, we achieved efficient cloning of long DNA fragments of different sizes and assembly of multiple gene cassettes. Finally, we engineered and validated the biosynthesis of betanin in wild tobacco (Nicotiana benthamiana) leaves and transgenic rice (Oryza sativa) using multigene stacking constructs based on TGSII-UNiE. In conclusion, UNiEDA is an efficient, convenient and low-cost method for DNA cloning and multigene stacking, and the TGSII-UNiE system has important application prospects for plant functional genomics, genetic engineering and synthetic biology research.

With the growing demand of supercritical carbon dioxide (SC-CO2) dyeing, it is important to precisely predict the dyeing effect of supercritical carbon dioxide. In this work, Generalized Regression Neural Network (GRNN) and Back Propagation Neural Network (BPNN) models have been employed to predict the dyeing effect of SC-CO2. These two models have been constructed based on published experimental data and calculated values. A total of 386 experimental data sets were used in the present work. In GRNN and BPNN models, two input parameters, such as temperature, pressure, dye stuff types, carrier types and dyeing time, were selected for the input layer and one variable, K/S value or dye-uptake, was used in the output layer. It was found that the values of mean-relative-error (MRE) for BPNN model and for GRNN model are 3.27–6.54% and 1.68–3.32%, respectively. The results demonstrate that both BPNN and GPNN models can accurately predict the effect of supercritical dyeing but the former is better than the latter.

In this paper, we propose a novel inter-cell handover approach from a new perspective in dense Heterogeneous and Small Cell Networks (HetSNets). We first devise a cell selection mechanism to choose a proper candidate small cell for the UEs that tend to implement inter-small cell handover (ICH). By exploiting the property of a typical non-concentric circle, i.e., circle of Apollonius, we then propose a novel analytical method for modeling inter-cell handover regions and present mathematical derivation to prove that the inter-small cell handover issues fit the property of the circle of Apollonius. We design an inter-cell handover algorithm (ICHA) by means of our proposed handover model to dynamically configure hysteresis margin and properly implement handover decision in terms of UE's mobility. Simulation results demonstrate that the proposed ICHA yields lower call drop rate and radio link failure rate than the conventional methods and hence achieve high Handover Performance Indicator (HPI). Keywords：Heterogeneous and Small cell Networks (HetSNets); Inter-Small cell Handover; Circle of Apollonius.