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Modification of polymers by using high thermal conductivity fillers has become a common strategy for enhancing thermal conductivity. The low thermal conductivity of poly-(vinylidene fluoride) (PVDF) limits its development and application in the field of heat dissipation. The distinctive phonon mode exhibited by reduced graphene oxide (RGO) demonstrates exceptional thermal conductivity. In this study, PVDF served as the matrix, and composite membranes were prepared by incorporating nanothermal conductive material (graphene). The objective of enhancing the thermal conductivity has been achieved. Experimental outcomes were derived through characterization. RGO sheets smaller than 10 μm were observed to maintain the external surface morphology of the membrane unchanged. The porosity exhibited a gradual increase with growing lamellar diameters. The membrane's thermal conductivity demonstrated an initial rise followed by a subsequent decline. The peak value reached 0.15 W/m K when the RGO size ranged from 1 to 3 μm. However, further enlargement of the graphene size resulted in a significant decrease in the thermal conductivity. The presence of large pores, induced by larger-size RGOs in PVDF, had a pronounced adverse impact on the membrane's thermal conductivity. The size, surface microstructure, dosage, and composite morphology of thermally conductive particles play a pivotal role in influencing mechanical, electrical, thermal, viscosity, structural control, and processability aspects. Thus, comprehending the morphology of thermally conductive particles holds significance in the exploration, formulation, and advancement of thermally conductive polymer materials. [ABSTRACT FROM AUTHOR]

The gaseous hormone ethylene plays a pivotal role in plant growth and development. In seed plants, the key rate-limiting enzyme that controls ethylene biosynthesis is ACC synthase (ACS). ACS has, for a long time, been believed to be a single-activity enzyme until we recently discovered that it also possesses Cβ-S lyase (CSL) activity. This discovery raises fundamental questions regarding the biological significance of the dual enzymatic activities of ACS. To address these issues, it is highly necessary to obtain ACS mutants with either ACS or CSL single activity. Here, domain swapping between Arabidopsis AtACS7 and moss CSL PpACL1 were performed. Enzymatic activity assays of the constructed chimeras revealed that, R10, which was produced by replacing AtACS7 box 6 with that of PpACL1, lost ACS but retained CSL activity, whereas R12 generated by box 4 substitution lost CSL and only had ACS activity. The activities of both chimeric proteins were compared with previously obtained single-activity mutants including R6, AtACS7Q98A, and AtACS7D245N. All the results provided new insights into the key residues required for ACS and CSL activities of AtACS7 and laid an important foundation for further in-depth study of the biological functions of its dual enzymatic activities. [ABSTRACT FROM AUTHOR]

Considerable signal crosstalk exists in the regulatory network of senescence and stress response. Numerous senescence‐associated genes are also involved in plant stress tolerance. However, the underlying mechanisms and application potential of these genes in stress‐tolerant crop breeding remain poorly explored. We found that overexpression of SENESCENCE‐SUPPRESSED PROTEIN PHOSPHATASE (SSPP), a negative regulator of leaf senescence, significantly improved plant salt tolerance by increasing reactive oxygen species (ROS) scavenging in both Arabidopsis and soybean. However, overexpression of SSPP severely suppressed normal plant growth, limiting its direct use in agriculture. We previously revealed that the N‐terminal 1–14 residues of ACS7 (termed 'N7') negatively regulated its protein stability through the ubiquitin/proteasome pathway, and the N7‐mediated protein degradation was suppressed by environmental and senescence signals. To avoid the adverse effects of SSPP, the N7 element was fused to the N‐terminus of SSPP. We demonstrated that N7‐SSPP fusion gene effectively rescued SSPP‐induced growth suppression but maintained enhanced salt tolerance in Arabidopsis and soybean. Particularly, N7‐SSPP enhanced tolerance to long‐term salt stress and increased seed yield in soybean. These results suggest that N7‐SSPP overcomes the disadvantages of SSPP on plant growth inhibition and effectively improves salt tolerance through enhanced ROS scavenging, providing an effective strategy of using posttranslational regulatory element for salt‐tolerant crop breeding. Numerous senescence‐associated genes are also involved in stress tolerance, but the underlying mechanisms and application potentials are poorly investigated. We found that SSPP, a negative regulator of leaf senescence, enhances plant salt tolerance through ROS scavenging. Fusing N7, a regulatory element in the N‐degron pathway, to SSPP rescued SSPP‐induced growth suppression but did not affect salt tolerance in Arabidopsis and soybean. Notably, N7‐SSPP enhanced long‐term salt tolerance and increased yield in soybean. This study supported that manipulation of key senescence‐associated genes can effectively modulate plant stress responses and provided an effective strategy of using regulatory elements in the N‐degron pathway for salt‐tolerant crop breeding. [ABSTRACT FROM AUTHOR]

The involvement of SMALL AUXIN-UP RNA (SAUR) proteins in leaf senescence has been more and more acknowledged, but the detailed mechanisms remain unclear. In the present study, we performed yeast two-hybrid assays and identified SAUR49 as an interactor of SENESCENCE SUPPRESSED PROTEIN PHOSPHATASE (SSPP), which is a PP2C protein phosphatase that negatively regulates Arabidopsis leaf senescence by suppressing the leucine-rich repeat receptor-like protein kinase SENESCENCE-ASSOCIATED RECEPTOR-LIKE KINASE (SARK), as reported previously by our group. The interaction between SAUR49 and SSPP was further confirmed in planta. Functional characterization revealed that SAUR49 is a positive regulator of leaf senescence. The accumulation level of SAUR49 protein increased during natural leaf senescence in Arabidopsis. The transcript level of SAUR49 was upregulated during SARK- induced premature leaf senescence but downregulated during SSPP- mediated delayed leaf senescence. Overexpression of SAUR49 significantly accelerated both natural and dark-induced leaf senescence in Arabidopsis. More importantly, SAUR49 overexpression completely reversed SSPP -induced delayed leaf senescence. In addition, overexpression of SAUR49 reversed the decreased plasma membrane H+-ATPase activity mediated by SSPP. Taken together, the results showed that SAUR49 functions in accelerating the leaf senescence process via the activation of SARK -mediated leaf senescence signaling by suppressing SSPP. We further identified four other SSPP-interacting SAURs, SAUR30, SAUR39, SAUR41 and SAUR72, that may act redundantly with SAUR49 in regulating leaf senescence. All these observations indicated that certain members of the SAUR family may serve as an important hub that integrates various hormonal and environmental signals with senescence signals in Arabidopsis. [ABSTRACT FROM AUTHOR]

The white potato cyst nematode, Globodera pallida, is an obligate biotrophic pathogen of a limited number of Solanaceous plants. Like other plant pathogens, G. pallida deploys effectors into its host that manipulate the plant to the benefit of the nematode. Genome analysis has led to the identification of large numbers of candidate effectors from this nematode, including the cyst nematode-specific SPRYSEC proteins. These are a secreted subset of a hugely expanded gene family encoding SPRY domain-containing proteins, many of which remain to be characterized. We investigated the function of one of these SPRYSEC effector candidates, GpSPRY-414-2. Expression of the gene encoding GpSPRY-414-2 is restricted to the dorsal pharyngeal gland cell and reducing its expression in G. pallida infective second stage juveniles using RNA interference causes a reduction in parasitic success on potato. Transient expression assays in Nicotiana benthamiana indicated that GpSPRY-414-2 disrupts plant defenses. It specifically suppresses effector-triggered immunity (ETI) induced by co-expression of the Gpa2 resistance gene and its cognate avirulence factor RBP-1. It also causes a reduction in the production of reactive oxygen species triggered by exposure of plants to the bacterial flagellin epitope flg22. Yeast two-hybrid screening identified a potato cytoplasmic linker protein (CLIP)-associated protein (StCLASP) as a host target of GpSPRY-414-2. The two proteins co-localize in planta at the microtubules. CLASPs are members of a conserved class of microtubule-associated proteins that contribute to microtubule stability and growth. However, disruption of the microtubule network does not prevent suppression of ETI by GpSPRY-414-2 nor the interaction of the effector with its host target. Besides, GpSPRY-414-2 stabilizes its target while effector dimerization and the formation of high molecular weight protein complexes including GpSPRY-414-2 are prompted in the presence of the StCLASP. These data indicate that the nematode effector GpSPRY-414-2 targets the microtubules to facilitate infection. [ABSTRACT FROM AUTHOR]

Abstract: YF3 is an important host matrix for lanthanides doping to give both strong down- and up-conversion luminescence with high quantum efficiency. Controlled synthesis of YF3 nanocrystals is an efficient route to obtain different YF3 nanocrystals satisfying for different applications and controlling their fluorescence. Here we present a facile approach to selectively synthesize different YF3 nanocrystals using ethylene glycol (EG) as solvent. Five distinct morphologies can be conveniently obtained through changing the fluoride sources and chelating ligands in the EG solution. The prepared products were characterized and their formation mechanisms were proposed. After doped with different lanthanides, these samples can give both down- and up-conversion luminescence, suggesting that they are good nanoparticulate hosts. A comparison of fluorescent intensities between different products has been made, offering us an opportunity to study the relationship between fluorescence intensities and morphologies of YF3 nanostructures. Our results suggest that formation of assemblies is a feasible way to enhance the fluorescence of lanthanide nanocrystals in addition to the size control. [Copyright &y& Elsevier]

Considerable signal crosstalk exists in the regulatory network of senescence and stress response. Numerous senescence-associated genes are also involved in plant stress tolerance. However, the underlying mechanisms and application potential of these genes in stress-tolerant crop breeding remain poorly explored. We found that overexpression of SENESCENCE-SUPPRESSED PROTEIN PHOSPHATASE (SSPP), a negative regulator of leaf senescence, significantly improved plant salt tolerance by increasing reactive oxygen species (ROS) scavenging in both Arabidopsis and soybean. However, overexpression of SSPP severely suppressed normal plant growth, limiting its direct use in agriculture. We previously revealed that the N-terminal 1-14 residues of ACS7 (termed 'N 7 ') negatively regulated its protein stability through the ubiquitin/proteasome pathway, and the N 7 -mediated protein degradation was suppressed by environmental and senescence signals. To avoid the adverse effects of SSPP, the N 7 element was fused to the N-terminus of SSPP. We demonstrated that N 7 -SSPP fusion gene effectively rescued SSPP-induced growth suppression but maintained enhanced salt tolerance in Arabidopsis and soybean. Particularly, N 7 -SSPP enhanced tolerance to long-term salt stress and increased seed yield in soybean. These results suggest that N 7 -SSPP overcomes the disadvantages of SSPP on plant growth inhibition and effectively improves salt tolerance through enhanced ROS scavenging, providing an effective strategy of using posttranslational regulatory element for salt-tolerant crop breeding., (© 2022 John Wiley & Sons Ltd.)

The white potato cyst nematode, Globodera pallida , is an obligate biotrophic pathogen of a limited number of Solanaceous plants. Like other plant pathogens, G. pallida deploys effectors into its host that manipulate the plant to the benefit of the nematode. Genome analysis has led to the identification of large numbers of candidate effectors from this nematode, including the cyst nematode-specific SPRYSEC proteins. These are a secreted subset of a hugely expanded gene family encoding SPRY domain-containing proteins, many of which remain to be characterized. We investigated the function of one of these SPRYSEC effector candidates, Gp SPRY-414-2. Expression of the gene encoding Gp SPRY-414-2 is restricted to the dorsal pharyngeal gland cell and reducing its expression in G. pallida infective second stage juveniles using RNA interference causes a reduction in parasitic success on potato. Transient expression assays in Nicotiana benthamiana indicated that Gp SPRY-414-2 disrupts plant defenses. It specifically suppresses effector-triggered immunity (ETI) induced by co-expression of the Gpa2 resistance gene and its cognate avirulence factor RBP-1 . It also causes a reduction in the production of reactive oxygen species triggered by exposure of plants to the bacterial flagellin epitope flg22. Yeast two-hybrid screening identified a potato cytoplasmic linker protein (CLIP)-associated protein ( St CLASP) as a host target of Gp SPRY-414-2. The two proteins co-localize in planta at the microtubules. CLASPs are members of a conserved class of microtubule-associated proteins that contribute to microtubule stability and growth. However, disruption of the microtubule network does not prevent suppression of ETI by Gp SPRY-414-2 nor the interaction of the effector with its host target. Besides, Gp SPRY-414-2 stabilizes its target while effector dimerization and the formation of high molecular weight protein complexes including Gp SPRY-414-2 are prompted in the presence of the St CLASP. These data indicate that the nematode effector Gp SPRY-414-2 targets the microtubules to facilitate infection.

Senescence is the final phase of leaf development, characterized by key processes by which resources trapped in deteriorating leaves are degraded and recycled to sustain the growth of newly formed organs. As the gaseous hormone ethylene exerts a profound effect on the progression of leaf senescence, both the optimal timing and amount of its biosynthesis are essential for controlled leaf development. The rate-limiting enzyme that controls ethylene synthesis in higher plants is ACC synthase (ACS). In this study, we evaluated the production of ethylene and revealed an up-regulation of ACS7 during leaf senescence in Arabidopsis . We further showed that the promoter activity of ACS7 was maintained at a relatively high level throughout the whole rosette development process. However, the accumulation level of ACS7 protein was extremely low in the light-grown young seedlings, and it was gradually restored as plants aging. We previously demonstrated that degradation of ACS7 is regulated by its first 14 N-terminal residues, here we compared the phenotypes of transgenic Arabidopsis overexpressing a truncated ACS7 lacking the 14 residues with transgenic plants overexpressing the full-length protein. Results showed that seedlings overexpressing the truncated ACS7 exhibited a senescence phenotype much earlier than their counterparts overexpressing the full-length gene. Fusion of the 14 residues to SSPP, a PP2C-type senescence-suppressed protein phosphatase, effectively rescued the SSPP -induced suppression of rosette growth and development but had no effect on the delayed senescence. This observation further supported that N-terminus-mediated degradation of ACS7 is negatively regulated by leaf senescence signaling. All results of this study therefore suggest that ACS7 is one of the major contributors to the synthesis of 'senescence ethylene'. And more importantly, the N-terminal 14 residue-mediated degradation of this protein is highly regulated by senescence signaling to enable plants to produce the appropriate levels of ethylene required.