The protein phosphatase (PP2C) gene family, known to participate in cellular processes, is one of the momentous and conserved plant-specific gene families that regulate signal transduction in eukaryotic organisms. Recently, PP2Cs were identified in Arabidopsis and various other crop species, but analysis of PP2C in cotton is yet to be reported. In the current research, we found 87 (Gossypium arboreum), 147 (Gossypium barbadense), 181 (Gossypium hirsutum), and 99 (Gossypium raimondii) PP2C-encoding genes in total from the cotton genome. Herein, we provide a comprehensive analysis of the PP2C gene family in cotton, such as gene structure organization, gene duplications, expression profiling, chromosomal mapping, protein motif organization, and phylogenetic relationships of each species. Phylogenetic analysis further categorized PP2C genes into 12 subgroups based on conserved domain composition analysis. Moreover, we observed a strong signature of purifying selection among duplicated pairs (i.e., segmental and dispersed) of Gossypium hirsutum. We also observed the tissue-specific response of GhPP2C genes in organ and fiber development by comparing the RNA-sequence (RNA-seq) data reported on different organs. The qRT-PCR validation of 30 GhPP2C genes suggested their critical role in cotton by exposure to heat, cold, drought, and salt stress treatments. Hence, our findings provide an overview of the PP2C gene family in cotton based on various bioinformatic tools that demonstrated their critical role in organ and fiber development, and abiotic stress tolerance, thereby contributing to the genetic improvement of cotton for the resistant cultivar.

To apply the high-precision realistic nucleon-nucleon (N N ) potentials on the investigations of relativistic many-body methods, the new versions of charge-dependent Bonn (CD-Bonn) N N potential are constructed within the pseudovector pion-nucleon coupling instead of the pseudoscalar type in the original CD-Bonn potential worked out by Machleidt [Phys. Rev. C 63, 024001 (2001)]. Two effective scalar mesons are introduced, whose coupling constants with nucleon are independently determined at each partial wave for total angular momentum J ≤ 4, to describe the charge dependence of N N scattering data precisely, while the coupling constants between vector, pseudovector mesons and nucleon are identical in all channels. Three revised CD-Bonn potentials adopting the pseudovector pion-nucleon couplings (pvCD-Bonn) are generated by fitting the Nijmegen PWA phase shift data and deuteron binding energy with different pion-nucleon coupling strengths, which can reproduce the phase shifts at spin-single channels and low-energy N N scattering parameters very well, and provide the significantly different mixing parameters at spintriplet channels. Furthermore, the D-state probabilities of deuteron from these potentials range from 4.22% to 6.05%. It demonstrates that these potentials contain different components of tensor force, which will be useful to discuss the roles of tensor force in nuclear few-body and many-body systems.

Properties of nuclear matter are investigated in the framework of relativistic Brueckner-Hartree-Fock model with the latest high-precision charge-dependent Bonn (pvCD-Bonn) potentials, where the coupling between pion and nucleon is adopted as pseudovector form. These realistic pvCD-Bonn potentials are renormalized to effective nucleon-nucleon (N N) interactions, G matrices. They are obtained by solving the Blankenbecler-Sugar (BbS) equation in nuclear medium. Then, the saturation properties of symmetric nuclear matter are calculated with pvCD-Bonn A, B, C potentials. The energies per nucleon are around −10.72 MeV to −16.83 MeV at saturation densities, 0.139 fm −3 to 0.192 fm −3 with these three potentials, respectively. It clearly demonstrates that the pseudovector coupling between pion and nucleon can generate reasonable saturation properties comparing with pseudoscalar coupling. Furthermore, these saturation properties have strong correlations with the tensor components of N N potentials, i.e., the D-state probabilities of deuteron, P D to form a relativistic Coester band. The equations of state of pure neutron matter from pvCD-Bonn potentials are almost identical, since the prominent difference of pvCD Bonn potentials are the components of tensor force, which provides very weak contributions in the case of total isospin T = 1. In addition, the charge symmetry breaking (CSB) and charge independence breaking (CIB) effects are also discussed in nuclear matter from the partial wave contributions with these highprecision charge-dependent potentials. In general, the magnitudes of CSB from the differences between nn and pp potentials are about 0.05 MeV, while those of CIB are around 0.35 MeV from the differences between np and pp potentials. Finally, the equations of state of asymmetric nuclear matter are also calculated with different asymmetry parameters. It is found that the effective neutron mass is larger than the proton one in neutron-rich matter.

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The momentum and isospin dependence of the single-particle potential for the in-medium nucleon are the key quantities in the Relativistic Brueckner–Hartree–Fock (RBHF) theory. It depends on how to extract the scalar and the vector components of the single-particle potential inside nuclear matter. In contrast to the RBHF calculations in the Dirac space with the positive-energy states (PESs) only, the single-particle potential can be determined in a unique way by the RBHF theory together with the negative-energy states, i.e., the RBHF theory in the full Dirac space. The saturation properties of symmetric and asymmetric nuclear matter in the full Dirac space are systematically investigated based on the realistic Bonn nucleon–nucleon potentials. In order to further specify the importance of the calculations in the full Dirac space, the neutron star properties are investigated. The direct URCA process in neutron star cooling will happen at density ρ DURCA = 0.43, 0.48, 0.52 fm−3 with proton fractions of Y p,DURCA = 0.13. The radii of a 1.4M ⊙ neutron star are predicated as R 1.4 M ⊙ = 11.97 , 12.13 , 12.27 km, and their tidal deformabilities are Λ 1.4 M ⊙ = 376 , 405 , 433 for potential Bonn A, B, C. Compared with the results obtained in the Dirac space with PESs only, the full-Dirac-space RBHF calculation predicts the softest symmetry energy, which would be more favored by the gravitational wave detection of GW170817. Furthermore, the results from the full-Dirac-space RBHF theory are consistent with the recent astronomical observations of massive neutron stars and simultaneous mass–radius measurement.

Properties of neutron stars are investigated by an available relativistic ab initio method, the relativistic Brueckner–Hartree–Fock (RBHF) model, with the latest high-precision, relativistic charge-dependent potentials, pvCD-Bonn A, B, C. The neutron star matter is solved within the beta equilibrium and charge neutrality conditions in the framework of the RBHF model. Compared to the conventional treatment, where the chemical potential of leptons was approximately represented by the symmetry energy of nuclear matter, the equation of state of neutron star matter in the present self-consistent calculation with pvCD-Bonn B has a striking difference above the baryon number density n b  = 0.55 fm−3. However, these differences influence the global properties of neutron stars only about 1% to 2%. Then, three two-body potentials pvCD-Bonn A, B, C, with different tensor components, are systematically applied in the RBHF model to calculate the properties of neutron stars. It is found that the maximum masses of neutron stars are around 2.21–2.30 M ⊙, and the corresponding radii are R = 11.18–11.72 km. The radii of a 1.4 M ⊙ neutron star are predicated as R 1.4 = 12.34–12.91 km, and their dimensionless tidal deformabilities are Λ1.4 = 485–626. Furthermore, the direct URCA process in neutron star cooling will happen from n b  = 0.414 to 0.530 fm−3 with the proton fractions Y p  = 0.136–0.138. All of the results obtained from the RBHF model only with two-body pvCD-Bonn potentials completely satisfy various constraints from recent astronomical observations of massive neutron stars, gravitational wave detection (GW170817), and simultaneous mass–radius measurement.

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IntroductionBiofuel is a kind of sustainable, renewable and environment friendly energy. Lignocellulose from the stems of woody plants is the main raw material for “second generation biofuels”. Lignin content limits fermentation yield and is therefore a major obstacle in biofuel production. Plant laccase plays an important role in the final step of lignin formation, which provides a new strategy for us to obtain ideal biofuels by regulating the expression of laccase genes to directly gain the desired lignin content or change the composition of lignin.MethodsMultiple sequence alignment and phylogenetic analysis were used to classify PtrLAC genes; sequence features of PtrLACs were revealed by gene structure and motif composition analysis; gene duplication, interspecific collinearity and Ka/Ks analysis were conducted to identify ancient PtrLACs; expression levels of PtrLAC genes were measured by RNA-Seq data and qRT-PCR; domain analysis combine with cis-acting elements prediction together showed the potential function of PtrLACs. Furthermore, Alphafold2 was used to simulate laccase 3D structures, proLAC23::LAC23-eGFP transgenic Populus stem transects were applied to fluorescence observation.ResultsA comprehensive analysis of the P. trichocarpa laccase gene (PtLAC) family was performed. Some ancient PtrLAC genes such as PtrLAC25, PtrLAC19 and PtrLAC41 were identified. Gene structure and distribution of conserved motifs clearly showed sequence characteristics of each PtrLAC. Combining published RNA-Seq data and qRT-PCR analysis, we revealed the expression pattern of PtrLAC gene family. Prediction results of cis-acting elements show that PtrLAC gene regulation was closely related to light. Through above analyses, we selected 5 laccases and used Alphafold2 to simulate protein 3D structures, results showed that PtrLAC23 may be closely related to the lignification. Fluorescence observation of proLAC23::LAC23-eGFP transgenic Populus stem transects and qRT-PCR results confirmed our hypothesis again.DiscussionIn this study, we fully analyzed the Populus trichocarpa laccase gene family and identified key laccase genes related to lignification. These findings not only provide new insights into the characteristics and functions of Populus laccase, but also give a new understanding of the broad prospects of plant laccase in lignocellulosic biofuel production.