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Drought and high-temperature stress are the main abiotic stresses that alone or simultaneously affect the yield and quality of pears worldwide. However, studies on the mechanisms of drought or high-temperature resistance in pears remain elusive. Therefore, the molecular responses of Pyrus betuleafolia, the widely used rootstock in pear production, to drought and high temperatures require further study. Here, drought- or high-temperature-resistant seedlings were selected from many Pyrus betuleafolia seedlings. The leaf samples collected before and after drought or high-temperature treatment were used to perform RNA sequencing analysis. For drought treatment, a total of 11,731 differentially expressed genes (DEGs) were identified, including 4444 drought-induced genes and 7287 drought-inhibited genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that these DEGs were more significantly enriched in plant hormone signal transduction, flavonoid biosynthesis, and glutathione metabolism. For high-temperature treatment, 9639 DEGs were identified, including 5493 significantly upregulated genes and 4146 significantly downregulated genes due to high-temperature stress. KEGG analysis showed that brassinosteroid biosynthesis, arginine metabolism, and proline metabolism were the most enriched pathways for high-temperature response. Meanwhile, the common genes that respond to both drought and high-temperature stress were subsequently identified, with a focus on responsive transcription factors, such as MYB, HSF, bZIP, and WRKY. These results reveal potential genes that function in drought or high-temperature resistance. This study provides a theoretical basis and gene resources for the genetic improvement and molecular breeding of pears. [ABSTRACT FROM AUTHOR]

Cold stress is a prominent abiotic factor that adversely affects the growth and yield of pears, consequently restricting the cultivation range and resulting in substantial economic losses for the pear industry. Basic region–leucine zipper (bZIP) transcription factors are widely involved in multiple physiological and biochemical activities of plants, particularly in response to cold stress. In this study, the responsiveness of PbbZIP11 in pear to cold stress was investigated, and its role was explored by using pear callus and Arabidopsis thaliana. The findings revealed that overexpression of PbbZIP11 enhanced the tolerance of pear callus and Arabidopsis thaliana to cold stress. The antioxidant enzyme activities of transgenic plants were enhanced and the expression of C-repeat binding transcription factor (CBF) genes was increased as compared to wild-type plants. To better understand the biological function of PbbZIP11, mRNAs were isolated from overexpressed and wild-type Arabidopsis thaliana after cold stress for whole-genome sequencing. The results showed that the expression of some CBF downstream target genes changed after exposure to cold stress. The results suggested that the PbbZIP11 gene could participate in cold-stress signaling through the CBF-dependent pathway, which provides a theoretical basis for the PbbZIP11-mediated response to cold stress and for the genetic breeding of pear varieties with low-temperature tolerance. [ABSTRACT FROM AUTHOR]

ADP-Glc pyrophosphorylase (AGPase), which catalyzes the transformation of ATP and glucose-1-phosphate (Glc-1-P) into adenosine diphosphate glucose (ADP-Glc), acts as a rate-limiting enzyme in crop starch biosynthesis. Prior research has hinted at the regulation of AGPase by phosphorylation in maize. However, the identification and functional implications of these sites remain to be elucidated. In this study, we identified the phosphorylation site (serine at the 31st position of the linear amino acid sequence) of the AGPase large subunit (Sh2) using iTRAQTM. Subsequently, to ascertain the impact of Sh2 phosphorylation on AGPase, we carried out site-directed mutations creating Sh2-S31A (serine residue replaced with alanine) to mimic dephosphorylation and Sh2-S31D (serine residue replaced with aspartic acid) or Sh2-S31E (serine residue replaced with glutamic acid) to mimic phosphorylation. Preliminary investigations were performed to determine Sh2 subcellular localization, its interaction with Bt2, and the resultant AGPase enzymatic activity. Our findings indicate that phosphorylation exerts no impact on the stability or localization of Sh2. Furthermore, none of these mutations at the S31 site of Sh2 seem to affect its interaction with Bt2 (smaller subunit). Intriguingly, all S31 mutations in Sh2 appear to enhance AGPase activity when co-transfected with Bt2, with Sh2-S31E demonstrating a substantial five-fold increase in AGPase activity compared to Sh2. These novel insights lay a foundational groundwork for targeted improvements in AGPase activity, thus potentially accelerating the production of ADP-Glc (the primary substrate for starch synthesis), promising implications for improved starch biosynthesis, and holding the potential to significantly impact agricultural practices. [ABSTRACT FROM AUTHOR]

The dynamic characteristics and thermal buckling behaviors of a multi-span honeycomb sandwich panel with arbitrary boundaries are studied comprehensively in this paper. The concept of artificial springs is proposed and it was found that arbitrary boundaries can be achieved by adjusting the stiffness of artificial springs. The hinges which connect the base plates of this structure are simulated by massless torsion springs. The displacement field of the panel is expressed as a series of admissible functions which is a set of characteristic orthogonal polynomials generated directly by employing the Gram–Schmidt process. The stresses induced by the temperature change in the multi-span panel are considered, and then the eigenvalue equations of free vibration and thermal buckling are derived by using the Rayleigh–Ritz method. The theoretical formulations of the present research are validated by comparing the results of this paper with those obtained from the available literature and ABAQUS software. Subsequently, the influences of structural parameters on the critical buckling temperature and natural frequencies are investigated comprehensively, and some useful conclusions about dynamic optimization design for multi-span honeycomb sandwich panels are drawn from the present study. [ABSTRACT FROM AUTHOR]

Sheath blight (ShB) of maize, as a soil-borne disease caused by Rhizoctonia solani AG1-IA, is one of the main obstacles for maintaining the sustainable production of maize. R. solani has a wide host range and low-resistance sources, there is a lack of resistant resources against ShB, and the damage caused by ShB cannot be effectively controlled. To effectively protect crops against ShB, it is necessary to combine information about its pathogenicity and about the disease prevention and control of the pathogenic fungus and to identify areas that require more in-depth research. While progress has been made in the identification of disease-related genes in corn and pathogens, their mechanisms remain unclear. Research related to disease control involves the use of agronomic methods, chemical control, biological control, and genetic improvement. Breeding and identification of high-resistant maize varieties are key and difficult points in the control of maize sheath blight. This article reviews the research progress of the symptoms, the pathogen's biological characteristics, the infection process, the pathogenic mechanism, and comprehensive control of maize sheath blight disease and provides future research directions of maize sheath blight in China. It aims to provide reliable technical routes and research ideas for future crop-disease-resistance research, especially to sheath blight of maize. [ABSTRACT FROM AUTHOR]

Starch phosphorylase (PHO) is a pivotal enzyme within the GT35-glycogen–phosphorylase (GT; glycosyltransferases) superfamily. Despite the ongoing debate surrounding the precise role of PHO1, evidence points to its substantial influence on starch biosynthesis, supported by its gene expression profile and subcellular localization. Key to PHO1 function is the enzymatic regulation via phosphorylation; a myriad of such modification sites has been unveiled in model crops. However, the functional implications of these sites remain to be elucidated. In this study, we utilized site-directed mutagenesis on the phosphorylation sites of Zea mays PHO1, replacing serine residues with alanine, glutamic acid, and aspartic acid, to discern the effects of phosphorylation. Our findings indicate that phosphorylation exerts no impact on the stability or localization of PHO1. Nonetheless, our enzymatic assays unveiled a crucial role for phosphorylation at the S566 residue within the L80 region of the PHO1 structure, suggesting a potential modulation or enhancement of PHO1 activity. These data advance our understanding of starch biosynthesis regulation and present potential targets for crop yield optimization. [ABSTRACT FROM AUTHOR]

ADP-Glc pyrophosphorylase (AGPase) is a pivotal enzyme catalyzing the conversion of ATP and glucose-1-phosphate (Glc-1-P) to adenosine diphosphate glucose (ADP-Glc), thereby serving as a rate-limiting factor in starch biosynthesis in crops. Although previous investigations have suggested phosphorylation-based regulation of AGPase in maize, the explicit modulation mechanisms have yet to be elucidated. This research evaluated the effect of point mutations at phosphorylation sites (identified using iTRAQTM AB SCIEX, Framingham, MA, USA) on the subcellular localization and activity of the AGPase small subunit Bt2, and its interaction with the large subunit Sh2, in maize. Despite the induction of point mutations, subcellular localization of the Bt2 subunit remained unaltered, primarily within the cytoplasm and nucleus. The interaction between Bt2 and Sh2 subunits continued, mainly in the chloroplast. Notably, an increase in AGPase activity was observed in the case of simulated phosphorylation point mutations, whereas dephosphorylation activity significantly diminished relative to the wild type. These findings demonstrate that point mutations do not affect the subcellular localization of the Bt2 subunit or its interaction with the Sh2 subunit, but substantially modulate AGPase activity. This study provides critical insights into the role of point mutations in enhancing AGPase activity, thus potentially accelerating the production of ADP-Glc, the primary substrate for starch synthesis, promising implications for improved starch biosynthesis in maize. [ABSTRACT FROM AUTHOR]

In order to investigate the crucial role of ZmBT1 in starch accumulation during maize grain development and analyze the expression and distribution of ZmBT1 in various maize tissues, we prepared a polyclonal antibody. Specifically, we successfully expressed the recombinant plasmid pGEX-6p-ZmBT1-C (382-437aa) and purified Gst-ZmBT1-C as the antigen for antibody preparation. Our results confirmed that the ZmBT1 protein in maize tissues can be specifically recognized by the ZmBT1 antibody. Through Western blotting, we observed that the expression protein of ZmBT1 varied by tissues, with the highest content in the grain and endosperm. Furthermore, we employed a combination of Western blotting and quantitative real-time PCR to show that the expression level of ZmBT1 can be influenced by plant hormones. This finding suggests that ZmBT1 plays a critical role in the accumulation of starch and opens up new avenues for functional studies of this protein. [ABSTRACT FROM AUTHOR]

Climate change has resulted in frequent heavy and prolonged rainfall events that exacerbate waterlogging stress, leading to the death of certain alpine Rhododendron trees. To shed light on the physiological and molecular mechanisms behind waterlogging stress in woody Rhododendron trees, we conducted a study of Rhododendron delavayi, a well-known alpine flower species. Specifically, we investigated the physiological and molecular changes that occurred in leaves of R. delavayi subjected to 30 days of waterlogging stress (WS30d), as well as subsequent post-waterlogging recovery period of 10 days (WS30d-R10d). Our findings reveal that waterlogging stress causes a significant reduction in CO2 assimilation rate, stomatal conductance, transpiration rate, and maximum photochemical efficiency of PSII (Fv/Fm) in the WS30d leaves, by 91.2%, 95.3%, 93.3%, and 8.4%, respectively, when compared to the control leaves. Furthermore, the chlorophyll a and total chlorophyll content in the WS30d leaves decreased by 13.5% and 16.6%, respectively. Both WS30d and WS30d-R10d leaves exhibited excessive H2O2 accumulation, with a corresponding decrease in lignin content in the WS30d-R10d leaves. At the molecular level, purine metabolism, glutathione metabolism, photosynthesis, and photosynthesis-antenna protein pathways were found to be primarily involved in WS30d leaves, whereas phenylpropanoid biosynthesis, fatty acid metabolism, fatty acid biosynthesis, fatty acid elongation, and cutin, suberin, and wax biosynthesis pathways were significantly enriched in WS30d-R10d leaves. Additionally, both WS30d and WS30d-R10d leaves displayed a build-up of sugars. Overall, our integrated transcriptomic, physiological, and metabolomic analysis demonstrated that R. delavayi is susceptible to waterlogging stress, which causes irreversible detrimental effects on both its physiological and molecular aspects, hence compromising the tree's ability to fully recover, even under normal growth conditions. [ABSTRACT FROM AUTHOR]

Iron is an essential trace element for plants; however, low bioactive Fe in soil continuously places plants in an Fe-deficient environment, triggering oxidative damage. To cope with this, plants make a series of alterations to increase Fe acquisition; however, this regulatory network needs further investigation. In this study, we found notably decreased indoleacetic acid (IAA) content in chlorotic pear (Pyrus bretschneideri Rehd.) leaves caused by Fe deficiency. Furthermore, IAA treatment slightly induced regreening by increasing chlorophyll synthesis and Fe2+ accumulation. At that point, we identified PbrSAUR72 as a key negative effector output of auxin signaling and established its close relationship to Fe deficiency. Furthermore, the transient PbrSAUR72 overexpression could form regreening spots with increased IAA and Fe2+ content in chlorotic pear leaves, whereas its transient silencing does the opposite in normal pear leaves. In addition, cytoplasm-localized PbrSAUR72 exhibits root expression preferences and displays high homology to AtSAUR40/72. This promotes salt tolerance in plants, indicating a putative role for PbrSAUR72 in abiotic stress responses. Indeed, transgenic plants of Solanum lycopersicum and Arabidopsis thaliana overexpressing PbrSAUR72 displayed less sensitivity to Fe deficiency, accompanied by substantially elevated expression of Fe-induced genes, such as FER/FIT, HA, and bHLH39/100. These result in higher ferric chelate reductase and root pH acidification activities, thereby hastening Fe absorption in transgenic plants under an Fe-deficient condition. Moreover, the ectopic overexpression of PbrSAUR72 inhibited reactive oxygen species production in response to Fe deficiency. These findings contribute to a new understanding of PbrSAURs and its involvement in Fe deficiency, providing new insights for the further study of the regulatory mechanisms underlying the Fe deficiency response. [ABSTRACT FROM AUTHOR]

Starch biosynthesis is a complex and highly controlled process that requires coordinated activities among multiple enzymes. Starch synthase III (SSIII) is the largest protein in the starch synthase complex and its function is to lengthen long-chain amylopectin in starch synthesis. It potentially affects the activity of other key enzymes in starch synthesis through protein–protein interactions; therefore, its function and regulation play a predominant role in starch synthesis. In this review, we summarized the main research of SSIII including its biochemical characteristics, structural features, expression atlas, and regulation means. Structural features and expressional analysis indicated that SSIIIa is the main functional protein in maize endosperm rather than SSIIIb-a and SSIIIb-b, even though they are similar in the tertiary structures. The regulation investigation of SSIIIa showed that there are 13 transcription factors that control the transcription of SSIIIa. Interaction network analysis showed that SSIIIa could be involved with ten other key enzymes in starch synthesis. In conclusion, this review considerably extends our understanding of SSIII and provides the theoretical basis for improving starch synthesis by SSIII in maize. [ABSTRACT FROM AUTHOR]

Starch phosphorylase (PHO) is a multimeric enzyme with two distinct isoforms: plastidial starch phosphorylase (PHO1) and cytosolic starch phosphorylase (PHO2). PHO1 specifically resides in the plastid, while PHO2 is found in the cytosol. Both play a critical role in the synthesis and degradation of starch. This study aimed to report the detailed structure, function, and evolution of genes encoding PHO1 and PHO2 and their protein ligand-binding sites in eight monocots and four dicots. "True" orthologs of PHO1 and PHO2 of Oryza sativa were identified, and the structure of the enzyme at the protein level was studied. The genes controlling PHO2 were found to be more conserved than those controlling PHO1; the variations were mainly due to the variable sequence and length of introns. Cis-regulatory elements in the promoter region of both genes were identified, and the expression pattern was analyzed. The real-time quantitative polymerase chain reaction indicated that PHO2 was expressed in all tissues with a uniform pattern of transcripts, and the expression pattern of PHO1 indicates that it probably contributes to the starch biosynthesis during seed development in Zea mays. Under abscisic acid (ABA) treatment, PHO1 was found to be downregulated in Arabidopsis and Hordeum vulgare. However, we found that ABA could up-regulate the expression of both PHO1 and PHO2 within 12 h in Zea mays. In all monocots and dicots, the 3D structures were highly similar, and the ligand-binding sites were common yet fluctuating in the position of aa residues. [ABSTRACT FROM AUTHOR]

People's movement trace harvested from mobile phone signals has become an important new data source for studying human behavior and related socioeconomic topics in social science. With growing concern about privacy leakage of big data, mobile phone data holders now tend to provide aggregate-level mobility data instead of individual-level data. However, most algorithms for measuring mobility are based on individual-level data—how the existing mobility algorithms can be properly transformed to apply on aggregate-level data remains undiscussed. This paper explores the transformation of individual data-based mobility metrics to fit with grid-aggregate data. Fifteen candidate metrics measuring five indicators of mobility are proposed and the most suitable one for each indicator is selected. Future research about aggregate-level mobility data may refer to our analysis to assist in the selection of suitable mobility metrics. [ABSTRACT FROM AUTHOR]

Starch phosphorylase is a member of the GT35-glycogen-phosphorylase superfamily. Glycogen phosphorylases have been researched in animals thoroughly when compared to plants. Genetic evidence signifies the integral role of plastidial starch phosphorylase (PHO1) in starch biosynthesis in model plants. The counterpart of PHO1 is PHO2, which specifically resides in cytosol and is reported to lack L80 peptide in the middle region of proteins as seen in animal and maltodextrin forms of phosphorylases. The function of this extra peptide varies among species and ranges from the substrate of proteasomes to modulate the degradation of PHO1 in Solanum tuberosum to a non-significant effect on biochemical activity in Oryza sativa and Hordeum vulgare. Various regulatory functions, e.g., phosphorylation, protein–protein interactions, and redox modulation, have been reported to affect the starch phosphorylase functions in higher plants. This review outlines the current findings on the regulation of starch phosphorylase genes and proteins with their possible role in the starch biosynthesis pathway. We highlight the gaps in present studies and elaborate on the molecular mechanisms of phosphorylase in starch metabolism. Moreover, we explore the possible role of PHO1 in crop improvement. [ABSTRACT FROM AUTHOR]

Alligator weed is reported to have a strong ability to adapt to potassium deficiency (LK) stress. Leaves are the primary organs responsible for photosynthesis of plants. However, quantitative proteomic changes in alligator weed leaves in response to LK stress are largely unknown. In this study, we investigated the physiological and proteomic changes in leaves of alligator weed under LK stress. We found that chloroplast and mesophyll cell contents in palisade tissue increased, and that the total chlorophyll content, superoxide dismutase (SOD) activity and net photosynthetic rate (PN) increased after 15 day of LK treatment, but the soluble protein content decreased. Quantitative proteomic analysis suggested that a total of 119 proteins were differentially abundant proteins (DAPs). KEGG analysis suggested that most represented DAPs were associated with secondary metabolism, the stress response, photosynthesis, protein synthesis, and degradation pathway. The proteomic results were verified using parallel reaction monitoring mass spectrometry (PRM–MS) analysis and quantitative real-time PCR (qRT-PCR)assays. Additional research suggested that overexpression of cationic peroxidase 1 of alligator weed (ApCPX1) in tobacco increased LK tolerance. The seed germination rate, peroxidase (POD) activity, and K+ content increased, and the hydrogen peroxide (H2O2) content decreased in the three transgenic tobacco lines after LK stress. The number of root hairs of the transgenic line was significantly higher than that of WT, and net K efflux rates were severely decreased in the transgenic line under LK stress. These results confirmed that ApCPX1 played positive roles in low-K+ signal sensing. These results provide valuable information on the adaptive mechanisms in leaves of alligator weed under LK stress and will help identify vital functional genes to apply to the molecular breeding of LK-tolerant plants in the future. [ABSTRACT FROM AUTHOR]

The accurate prediction of urban growth is pivotal for managing urbanization, especially in fast-urbanizing countries. For this purpose, cellular automata-based (CA) simulation tools have been widely developed and applied. Previous studies have extensively discussed various model building and calibration techniques to improve simulation performance. However, it has been a common practice that the simulation is conducted at and only at the spatial extent where the results are needed, while as we know, urban development in one place can also be influenced by the situations in the broader contexts. To tackle this gap, in this paper, the impact of the simulation of spatial extent on simulation performance is tested and discussed. We used five villages at the rural–urban fringe in Chengdu, China as the case study. Urban growth CA models are built and trained at the spatial extent of the village and the whole city. Comparisons between the simulation results and the actual urban growth in the study area from 2005 to 2015 show that the accuracy of the city model was 7.33% higher than the village model and the latter had more errors in simulating the growth of small clusters. Our experiment suggests that, at least in some cases, urban growth modeling at a larger spatial extent can yield better results than merely modeling the area of interest, and the impacts of the spatial extent of simulation should be considered by modelers. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is an important mineral nutrient for plant growth and development. Overexpressing AtWRKY6 (35S:WRKY6-9) was more sensitive and wrky6 ( wrky6-1 ) was more resistant under low Pi conditions. To better understand the function of AtWRKY6 under low phosphate stress conditions, we applied two-dimensional gel electrophoresis (2-DE) to analyse differentially expressed proteins in the shoots and roots between wild type, 35S:WRKY6-9 and wrky6-1 after phosphorus deficiency treatment for three days. The results showed 88 differentially abundant protein spots, which were identified between the shoots and roots of 35S:WRKY6-9 and wrky6-1 plants. In addition, 59 differentially expressed proteins were identified in the leaves and roots of 35S:WRKY6-9 plants. After analysis, 9 genes with W-box elements in their promoter sequences were identified in the leaves, while 6 genes with W-box elements in their promoter sequences were identified in the roots. A total of 8 genes were identified as potential target genes according to the quantitative PCR (QPCR) and two dimension difference gel electrophoresis, (2D-DIGE) results, including ATP synthase, gln synthetase, nitrilase, 14-3-3 protein, carbonic anhydrases 2, and tryptophan synthase. These results provide important information concerning the AtWRKY6 regulation network and reveal potential vital target genes of AtWRKY6 under low phosphorus stress. two dimension difference gel electrophoresis, 2D-DIGE.