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A comparative experimental and numerical study of the impact behaviour of carbon-fiber-reinforced thermoplastic (TP) and thermoset (TS) composites has been carried out. On the one hand, low velocity impact (LVI) tests were performed on TP and TS composites with different lay-up sequences at different energy levels, and the damage modes and microscopic damage mechanisms after impact were investigated using macroscale inspection, C-scan inspection, and X-ray-computed tomography. The comparative results show that the initial damage valve force under LVI depends not only on the material, but also on the layup sequence. The initial valve force of the P2 soft layer with lower stiffness is about 11% lower than that of the P1 quasi-isotropic layer under the same material, while the initial valve force of thermoplastic composites is about 28% lower than that of thermoset composites under the same stacking order. Under the same stacking order and impact energy level, the damage area and depth of TP composites are smaller than those of TS composites; while under the same material and impact energy level, the indentation depth of P2 plies is greater than that of P1 plies, and the damage area of P2 plies is smaller than that of P1 plies, but the change of thermoplastic composites is not as obvious as that of thermoset composites. This indicates that TP composites have a higher initial damage threshold energy and impact resistance at the same lay-up order, while increasing the lay-up ratio of the same material by 45° improves the impact resistance of the structure. In addition, a damage model based on continuum damage mechanics (CDM) was developed to predict different damage modes of thermoplastic composites during low velocity impact, and the analytical results were compared with the experimental results. At an impact energy of 4.45 J/mm, the error of the initial damage valve force is 5.26% and the error of the maximum impact force is 4.36%. The simulated impact energy and impact velocity curves agree with the experimental results, indicating that the finite element model has good reliability. [ABSTRACT FROM AUTHOR]

SUMMARY The diversity in alternative splicing of long noncoding RNAs (lncRNAs) poses a challenge for functional annotation of lncRNAs. Moreover, little is known on the effects of alternatively spliced lncRNAs on crop yield. In this study, we cloned nine isoforms resulting from the alternative splicing of the lncRNA LAIR in rice. The LAIR isoforms are generated via alternative 5′/3′ splice sites and different combinations of specific introns. All LAIR isoforms activate the expression of the neighboring LRK1 gene and enhance yield‐related rice traits. In addition, there are slight differences in the binding ability of LAIR isoforms to the epigenetic modification‐related proteins OsMOF and OsWDR5, which affect the enrichment of H4K16ac and H3K4me3 at the LRK1 locus, and consequently fine‐tune the regulation of LRK1 expression and yield‐related traits. These differences in binding may be caused by polymorphic changes to the RNA secondary structure resulting from alternative splicing. It was also observed that the composition of LAIR isoforms was sensitive to abiotic stress. These findings suggest that the alternative splicing of LAIR leads to the formation of a functional transcript population that precisely regulates yield‐related gene expression, which may be relevant for phenotypic polymorphism‐based crop breeding under changing environmental conditions. [ABSTRACT FROM AUTHOR]

Background: Yield and quality are the two most important traits in crop breeding. Exploring the regulatory mechanisms that affect both yield and quality traits is of great significance for understanding the molecular genetic networks controlling these key crop attributes. Expansins are cell wall loosening proteins that play important roles in regulating rice grain size. Results: We investigated the effect of OsEXPA7, encoding an expansin, on rice grain size and quality. OsEXPA7 overexpression resulted in increased plant height, panicle length, grain length, and thousand-grain weight in rice. OsEXPA7 overexpression also affected gel consistency and amylose content in rice grains, thus affecting rice quality. Subcellular localization and tissue expression analyses showed that OsEXPA7 is localized on the cell wall and is highly expressed in the panicle. Hormone treatment experiments revealed that OsEXPA7 expression mainly responds to methyl jasmonate, brassinolide, and gibberellin. Transcriptome analysis and RT-qPCR experiments showed that overexpression of OsEXPA7 affects the expression of OsJAZs in the jasmonic acid pathway and BZR1 and GE in the brassinosteroid pathway. In addition, OsEXPA7 regulates the expression of key quantitative trait loci related to yield traits, as well as regulates the expression levels of BIP1 and bZIP50 involved in the seed storage protein biosynthesis pathway. Conclusions: These results reveal that OsEXPA7 positively regulates rice yield traits and negatively regulates grain quality traits by involving plant hormone pathways and other trait-related pathway genes. These findings increase our understanding of the potential mechanism of expansins in regulating rice yield and quality traits and will be useful for breeding high-yielding and high-quality rice cultivars. [ABSTRACT FROM AUTHOR]

Symbiotic nitrogen fixation (SNF) is a crucial process for nitrogen geochemical cycling and plant‐microbe interactions. Water‐soluble humic acid (WSHM), an active component of soil humus, has been shown to promote SNF in the legume‐rhizobial symbiosis, but its molecular mechanism remains largely unknown. To reveal the SNF‐promoting mechanism, we conducted transcriptomic analysis on soybean treated with WSHM. Our findings revealed that up‐ and downregulated differentially expressed genes (DEGs) were mainly involved in plant cell‐wall/membrane formation and plant defence/immunity in the early stage, while the late stage was marked by the flavonoid synthesis and ethylene biosynthetic process. Further study on representative DEGs showed that WSHM could inhibit GmBAK1d‐mediated immunity and BR signalling, thereby promoting rhizobial colonisation, infection, and nodulation, while not favoring pathogenic bacteria colonisation on the host plant. Additionally, we also found that the ethylene pathway is necessary for promoting the soybean nodulation by WSHM. This study not only provides a significant advance in our understanding of the molecular mechanism of WSHM in promoting SNF, but also provides evidence of the beneficial interactions among the biostimulator, host plant, and soil microbes, which have not been previously reported. Summary Statement: Water‐soluble humic acid promoted soybean‐rhizobia symbiosis and nodulation by inhibiting host immunity and ethylene pathway, without sacrificing defence to the pathogenic bacteria. [ABSTRACT FROM AUTHOR]

Background: As part of the plant microbiome, endophytic bacteria play an essential role in plant growth and resistance to stress. Water-soluble humic materials (WSHM) is widely used in sustainable agriculture as a natural and non-polluting plant growth regulator to promote the growth of plants and beneficial bacteria. However, the mechanisms of WSHM to promote plant growth and the evidence for commensal endophytic bacteria interaction with their host remain largely unknown. Here, 16S rRNA gene sequencing, transcriptomic analysis, and culture-based methods were used to reveal the underlying mechanisms. Results: WSHM reduced the alpha diversity of soybean endophytic bacteria, but increased the bacterial interactions and further selectively enriched the potentially beneficial bacteria. Meanwhile, WSHM regulated the expression of various genes related to the MAPK signaling pathway, plant-pathogen interaction, hormone signal transduction, and synthetic pathways in soybean root. Omics integration analysis showed that Sphingobium was the genus closest to the significantly changed genes in WSHM treatment. The inoculation of endophytic Sphingobium sp. TBBS4 isolated from soybean significantly improved soybean nodulation and growth by increasing della gene expression and reducing ethylene release. Conclusion: All the results revealed that WSHM promotes soybean nodulation and growth by selectively regulating soybean gene expression and regulating the endophytic bacterial community, Sphingobium was the key bacterium involved in plant-microbe interaction. These findings refined our understanding of the mechanism of WSHM promoting soybean nodulation and growth and provided novel evidence for plant-endophyte interaction. [ABSTRACT FROM AUTHOR]

RNA‐binding proteins (RBPs) are components of the post‐transcriptional regulatory system, but their regulatory effects on complex traits remain unknown. Using an integrated strategy involving map‐based cloning, functional characterizations, and transcriptomic and population genomic analyses, we revealed that RBP‐K (LOC_Os08g23120), RBP‐A (LOC_Os11g41890), and RBP‐J (LOC_Os10g33230) encode proteins that form an RBP‐A‐J‐K complex that negatively regulates rice yield‐related traits. Examinations of the RBP‐A‐J‐K complex indicated RBP‐K functions as a relatively non‐specific RBP chaperone that enables RBP‐A and RBP‐J to function normally. Additionally, RBP‐J most likely affects GA pathways, resulting in considerable increases in grain and panicle lengths, but decreases in grain width and thickness. In contrast, RBP‐A negatively regulates the expression of genes most likely involved in auxin‐regulated pathways controlling cell wall elongation and carbohydrate transport, with substantial effects on the rice grain filling process as well as grain length and weight. Evolutionarily, RBP‐K is relatively ancient and highly conserved, whereas RBP‐J and RBP‐A are more diverse. Thus, the RBP‐A‐J‐K complex may represent a typical functional model for many RBPs and protein complexes that function at transcriptional and post‐transcriptional levels in plants and animals for increased functional consistency, efficiency, and versatility, as well as increased evolutionary potential. Our results clearly demonstrate the importance of RBP‐mediated post‐transcriptional regulation for the diversity of complex traits. Furthermore, rice grain yield and quality may be enhanced by introducing various complete or partial loss‐of‐function mutations to specific RBP genes using clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR‐associated protein 9 technology and by exploiting desirable natural tri‐genic allelic combinations at the loci encoding the components of the RBP‐A‐J‐K complex through marker‐assisted selection. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomer (MRE) is a novel intelligent material, which shows excellent potential in vibration control applications. Previous researches have fully demonstrated that the magneto-induced shear storage modulus of MRE largely determines the vibration control effect. However, both existing theoretical and experimental ways to measure the magneto-induced shear storage modulus of MRE face their own shortage. Therefore, a novel physics-guided deep learning model is proposed to efficient predict the magneto-induced mechanical properties of MRE based on Magnetic Dipole theory and data-driven methods. A small database is built by collecting the magneto-induced shear storage modulus of MRE with different material ratios tested on a special shear rheometer. The proposed model trained with small training samples and its prediction results fit well with experimental values (average R2 of 0.99) which is superior to existing constitutive models. The training only takes 25 s, which significantly shortens the time compared to the experiment. Furthermore, the proposed model effectively predicts the magneto-induced storage modulus of MRE and has good generalization and superior transfer performance. [Display omitted] [ABSTRACT FROM AUTHOR]

The pulse force generated by the propeller excites the hull through the propulsion shafting system, which is the primary source of vibration and noise of ships. In order to control the transmission of longitudinal vibration of ship shafting, a multimodal dynamic vibration absorber (MDVA) with broadband vibration control performance is proposed. A magnetorheological elastomer (MRE) was prepared and used as an elastic element to construct a semi-active dynamic vibration absorber (SDVA), designed spiral flexible springs and embedded SDVA into the proposed MDVA. An equivalent propeller propulsion shaft system model was established, and its first three longitudinal vibrations were controlled based on the MDVA. Furthermore, the stiffness and damping of the MDVA were optimized by fixed point theory. A design scheme for the MDVA considering the changes in oil film stiffness of thrust bearings under different propeller speed conditions was proposed. The results indicate that the MDVA has excellent vibration transmission control performance at the first three natural frequencies. The proposed MDVA also has a broader frequency band for controlling vibration near first-order resonance than the traditional single degree of freedom DVA, which has excellent vibration control performance under variable speed conditions. [ABSTRACT FROM AUTHOR]