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This report focuses on the crucial role of lipids and starch metabolism in the growth and ultrastructure of the cell wall (CW) in rice calli. Non-habituated calli (NH-calli) were isolated from a rice embryo-derived callus culture supplemented with 2,4-D (2,4-Dichlorophenoxyacetic acid); however, the habituated calli (H-calli) were isolated from NH ones and cultured subsequently on exogenous hormone-free medium. The phenotypes of the H- and NH-calli differed significantly between each other as reported in our recently published work. The H-calli CW was thinner, the endoplasmic reticulum (ER), mitochondria (MT) and starch grains (SGs) were less in the H-calli. The intracellular free fatty acids (FAs) and starch content were much less in the H- if compared to NH-calli. By microarray analysis, the differentially expressed genes (DEGs) related to primary and secondary metabolism, lipid and starch metabolism were down-regulated in H- vs NH-calli. The response at the transcriptomic level involved in these changes, as well as the corresponding variations in cytology and FAs metabolism were also accurately elucidated herein. The study reveals that the decreased levels of lipids and starch in the H-calli are mainly attributable to their (H-calli) elevated consumption, in the absence of exogenous hormonal supply to ensure the demand in energy of the calli to survive and maintain an optimum growth and development with the available resource of energy (starch and lipids). This report displays as well the slowdown of the H-calli metabolism, in the absence of exogenous growth regulators supply, if compared to that of the NH-ones. Lipids and starch decreased in the H-calli is mainly attributable to their elevated consumption to survive and maintain an optimal growth and development with the available resource of energy.

The habituated rice calli grown on an auxin-free medium were isolated from rice embryo-derived calli previously cultivated on medium supplemented with 2,4-D. The habituated rice calli grow faster than the non-habituated ones, particularly during the first week. We performed microarray analysis to unravel the changes in the transcriptomic level of rice calli grown on hormone-free medium. Several genes related to hormone metabolism and signaling were differentially expressed between the two calli types. Especially, the expressions of two amido-transferase enzymes genes Gretchen Hagen 3s (GH3.1 and GH3.8) were down-regulated and one indole-3-acetic acid (IAA)-amino acid (IAA-AA) hydrolase gene ILR1-like 3 was up-regulated in habituated calli compared to non-habituated. We further assessed the contents of different hormones in these two calli kinds. The IAA content was indeed significantly increased by about 7 times in habituated calli compared to non-habituated, initially grown in plant hormone-free medium. In parallel to the increase in the endogenous auxin, IAA-AA conjugates, abscisic acid (ABA), ethylene and GA12, GA19, GA29 were decreased in the habituated calli. Our results indicate that the regeneration of endogenous auxin is essential and required for the habituation of callus cells. The changes in the endogenous hormones might be coordinated and monitored during the habituation process by various biological pathways. Eventually, this study debates the interrelated changes and adjustment in endogenous plant hormones occurred (happened) in the habituated calli. This report exhibits also a completely different hormonal composition status for each rice calli, which might potentially be responsible for the calli growth regulation and its acclimation process.

The plant stress hormone salicylic acid (SA) participates in local and systemic acquired resistance, which eventually leads to whole-plant resistance to bacterial pathogens. However, if SA-mediated signaling is not appropriately controlled, plants incur defense-associated fitness costs such as growth inhibition and cell death. Despite its importance, to date only a few components counteracting the SA-primed stress responses have been identified in Arabidopsis (Arabidopsis thaliana). These include other plant hormones such as jasmonic acid and abscisic acid, and proteins such as LESION SIMULATING DISEASE1, a transcription coregulator. Here, we describe PLANT NATRIURETIC PEPTIDE A (PNP-A), a functional analog to vertebrate atrial natriuretic peptides, that appears to antagonize the SA-mediated plant stress responses. While loss of PNP-A potentiates SA-mediated signaling, exogenous application of synthetic PNP-A or overexpression of PNP-A significantly compromises the SA-primed immune responses. Moreover, we identify a plasma membrane–localized receptor-like protein, PNP-R2, that interacts with PNP-A and is required to initiate the PNP-A–mediated intracellular signaling. In summary, our work identifies a peptide and its putative cognate receptor as counteracting both SA-mediated signaling and SA-primed cell death in Arabidopsis.

The weak interfacial interactions between carbon nanotube (CNT) always results in low stress load transfer efficiency in CNT yarns, herein we fabricated strong, highly conducting CNT yarns at room temperature using molecules having aromatic end groups, π bridging neighboring CNTs. The resulting CNT yarns have high tensile strength with 1697 ± 24 MPa, toughness with 18.6 ± 1.6 MJ/m3, and electrical conductivity with 656.2 S/cm, which are 3.9, 2.5, and 3.5 times, respectively, as high as that of the neat CNT yarn. The specific tensile strength of the resulting CNT yarn is higher than that for previously reported CNT yarns fabricated at room temperature, even that for some CNT yarns fabricated using corossive environments or extreme temperature. This π bridging strategy provides a promising avenue for fabricating high performance CNT yarns under ambient conditions.

It is very difficult to observe the deformation of the surrounding rock within a very short time after excavation in hard rock such as granite. This paper reports an in situ monitoring test of the internal displacement of the surrounding rock conducted using multi-point extensometers that were pre-embedded before excavation in the Beishan Exploration Tunnel (BET) in China's Gansu Province. The internal deformation characteristics of the surrounding rock throughout the whole tunnel excavation process were analyzed, and an analysis of the spatial effect of the tunnel excavation face and an estimation of the loss displacement were carried out with 3 typical longitudinal deformation profile (LDP) curve equations: the Lee equation, the Hoek equation and the Vlachopoulos and Diederichs (V-D) equation. The results show that under the geological conditions of Beishan granite, the internal displacement of the surrounding rock throughout the whole process of blasting excavation passes through 3 stages, including initial growth, rapid growth and stable convergence. The temporal curve of the internal displacement of the surrounding rock near a measuring section shows stepwise characteristics, which are similar to the morphological characteristics of a creep test curve for rock subjected to graded loading. Measuring points farther from the side wall of the tunnel are less affected by the spatial effect of the tunnel excavation face and experience a larger displacement release ahead of the tunnel face relative to the total displacement. The loss displacement calculated with the Hoek equation is closest to the measured value; thus, the Hoek equation is the optimal estimation equation. When the measuring section is located 2 m from the tunnel face, the loss displacement accounts for more than 50% of the total displacement.

A highly regioselective copper-catalyzed 1,4-chloro- and bromotrifluoromethylation of 1,3-enynes has been presented for the first time, which affords an efficient transformation to access halo- and CF3-containing tetrasubstituted allene derivatives with good to excellent yield. This protocol is practical and convenient, in which a wide range of functional groups are compatible. Applications of this method for the gram-scale preparation and late-stage functionalization of biologically active molecules are also demonstrated.

The increasing demands for real-time marine monitoring call for the wide deployment of Marine Monitoring Networks (MMNs). The low-rate underwater communications over a long distance, long propagation delay of underwater acoustic channel, and high deployment costs of marine sensors in a large-scale three-dimensional space bring great challenges in the network deployment and management of MMN. In this paper, we first propose a multitier, hierarchical network architecture of MMN with the support of edge computing (HMMN-EC) to enable efficient monitoring services in a harsh marine environment, taking into consideration the salient features of marine communications. Specifically, HMMN-EC is composed of three subnetworks, i.e., underwater acoustic subnetwork, the sea-surface wireless subnetwork, and the air wireless subnetwork, with a diversity of network nodes with different capabilities. We then jointly investigate the deployment diverse network nodes with various constraints in different subnetworks of HMMN-EC. To this end, we formulate a Multiobjective Optimization (MO) problem to minimize the network deployment cost while achieving the maximal network lifetime, subject to the limited energy of different marine nodes and the complex deployment environment. To solve the formulated problem, we present an Ant-Colony-based Efficient Topology Optimization (AC-ETO) algorithm to find the optimal locations of nodes in different subnetworks of MMN in a large-scale deployment. The time complexity of the proposed algorithm is also analyzed. Finally, extensive simulations are carried out to validate the superior performance of the proposed algorithm compared with some existing solutions.

In the study, a self-developed Split Hopkinson pressure bar apparatus with triaxial confining pressure was used to examine the dynamic compression property of salt rock under confining pressures of 5, 15, and 25 MPa. To examine the dynamic properties of salt rock, Yingcheng salt rock from Hubei province in China was considered. Dynamic stress–strain curves of salt rock under different confining pressures and strain rates were obtained. The results indicated that the peak stress and ductility of salt rock increased with increase in the strain rate although the strain rate strengthening effect of the salt rock was not evident with increase in the confining pressure. The dynamic properties and disintegration characteristics were investigated on the basis of the energy dissipation principle. The energy delivery and transformation in the entire experimental process were analyzed in detail. Under the same confining pressure, the hardening effect of the salt rock was more evident with increase in the incident energy, and this can be explained by the decrease in the energy transmission/absorption rate when the reflectance rate increased. Contrary to the plastic damage characteristics under quasi-static triaxial compression, the salt rock exhibited evident brittle fracture characteristics under dynamic compressive loading. The peak stress of the salt rock revealed different trends with the increase in energy absorption under different confining pressures. Increased energy absorption and higher peak stress were observed under low confining pressure. However, the peak stress significantly decreased with increase in the energy absorption under high confining pressure.

The transcription factors EIN3 (ETHYLENE-INSENSITIVE 3) and EILs (EIN3-Likes) play important roles in plant development and defense responses; however, their mechanism in these processes remain unclear. Here, we report that OsEIL2, an EIN3-like transcription factor from rice (Oryza sativa), plays important roles in abiotic stress and leaf senescence. OsEIL2 is a nuclear-localized protein with transactivation activity in the C-terminus (amino acids 344-583) and can be induced by NaCl, polyethylene glycol (PEG), dark, and abscisic acid (ABA) treatment. Transgenic plants of overexpressing OsEIL2 (OsEIL2-OX) show reduced tolerance to salt and drought stress compared with the controls. While the transgenic plants of overexpressing OsEIL2-RNA interference (OsEIL2-RNAi) exhibit enhanced tolerance to salt and drought stress compared with the controls. Moreover, seedlings of OsEIL2-overexpressing transgenic plants exhibit delayed leaf development and an accelerated dark-induced senescence phenotype, whereas OsEIL2-RNAi plants display the opposite phenotype. We further found that OsEIL2 functions upstream of OsBURP14 and OsBURP16. OsBURP14 and OsBURP16 are the members of the β subunit of polygalacturonase subfamilies. OsBURP16 overexpression reduced pectin content and cell adhesion and increased abiotic stress sensitivity in rice. OsEIL2 binds directly to the promoter of OsBURP14 and OsBURP16 and activates their transcript levels. We also found that OsEIL2 overexpression decreased the pectin content by increasing polygalacturonase (PG) activity. Taken together, these results revealed a new mechanism of OsEIL2 in abiotic stress responses. These findings provide new insights into plant resistance to abiotic stress.

Photosystem II reaction center (PSII RC) and light-harvesting complex (LHC) inevitably generate highly reactive singlet oxygen (1O2) that can impose photo-oxidative damage, especially when the rate of generation exceeds the rate of detoxification. Besides being toxic, 1O2 has also been ascribed to trigger retrograde signaling, which leads to nuclear gene expression changes. Two distinctive molecular components appear to regulate 1O2 signaling: a volatile signaling molecule s-cyclocitral (s-CC) generated upon oxidation of s-carotene by 1O2 in PSII RC assembled in grana core, and a thylakoid membrane-bound FtsH2 metalloprotease that promotes 1O2-triggered signaling through the proteolysis of EXECUTER1 (EX1) proteins associated with PSII in grana margin. The role of FtsH2 protease in 1O2 signaling was established recently in the conditional fluorescent (flu) mutant of Arabidopsis thaliana that generates 1O2 upon dark-to-light shift. The flu mutant lacking functional FtsH2 significantly impairs 1O2-triggered and EX1-mediated cell death. In the present study, the role of FtsH2 in the induction of 1O2 signaling was further clarified by analyzing the FtsH2-dependent nuclear gene expression changes in the flu mutant. Genome-wide transcriptome analysis showed that the inactivation of FtsH2 repressed the majority (85%) of the EX1-dependent 1O2-responsive genes (ESORGs), providing direct connection between FtsH2-mediated EX1 degradation and 1O2-triggered gene expression changes. Furthermore, the overlap between β-CC-induced genes and EX1-FtsH2-dependent genes was very limited, further supporting the coexistence of two distinctive 1O2 signaling pathways.