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<jats:p>Regeneration is extremely important to pepper genetic development; however, the molecular mechanisms of how the callus reactivates cell proliferation and promotes cell reprogramming remain elusive in pepper. In the present study, <jats:italic>C. baccatum</jats:italic> (HNUCB81 and HNUCB226) and <jats:italic>C. chinense</jats:italic> (HNUCC22 and HNUCC16) were analyzed to reveal callus initiation by <jats:italic>in vitro</jats:italic> regeneration, histology, and transcriptome. We successfully established an efficient <jats:italic>in vitro</jats:italic> regeneration system of two cultivars to monitor the callus induction of differential genotypes, and the regenerated plants were obtained. Compared to <jats:italic>C. chinense</jats:italic>, there was a higher callus induction rate in <jats:italic>C. baccatum</jats:italic>. The phenotype of <jats:italic>C. baccatum</jats:italic> changed significantly and formed vascular tissue faster than <jats:italic>C. chinense</jats:italic>. The KEGG enrichment analysis found that plant hormone transduction and starch and sucrose metabolism pathways were significantly enriched. In addition, we identified that the <jats:italic>WOX7</jats:italic> gene was significantly up-regulated in HNUCB81 and HNUCB226 than that in HNUCC22 and HNUCC16, which may be a potential function in callus formation. These results provided a promising strategy to improve the regeneration and transformation of pepper plants.</jats:p>

<jats:p>Nod factors secreted by nitrogen-fixing rhizobia are lipo-chitooligosaccharidic signals required for establishment of the nodule symbiosis with legumes. In <jats:italic>Medicago truncatula</jats:italic>, the Nod factor hydrolase 1 (MtNFH1) was found to cleave Nod factors of <jats:italic>Sinorhizobium meliloti</jats:italic>. Here, we report that the class V chitinase MtCHIT5b of <jats:italic>M. truncatula</jats:italic> expressed in <jats:italic>Escherichia coli</jats:italic> can release lipodisaccharides from Nod factors. Analysis of <jats:italic>M. truncatula</jats:italic> mutant plants indicated that MtCHIT5b, together with MtNFH1, degrades <jats:italic>S. meliloti</jats:italic> Nod factors in the rhizosphere. <jats:italic>MtCHIT5b</jats:italic> expression was induced by treatment of roots with purified Nod factors or inoculation with rhizobia. MtCHIT5b with a fluorescent tag was detected in the infection pocket of root hairs. Nodulation of a <jats:italic>MtCHIT5b</jats:italic> knockout mutant was not significantly altered whereas overexpression of <jats:italic>MtCHIT5b</jats:italic> resulted in fewer nodules. Reduced nodulation was observed when <jats:italic>MtCHIT5b</jats:italic> and <jats:italic>MtNFH1</jats:italic> were simultaneously silenced in RNA interference experiments. Overall, this study shows that nodule formation of <jats:italic>M. truncatula</jats:italic> is regulated by a second Nod factor cleaving hydrolase in addition to MtNFH1.</jats:p>

<jats:p>In wheat, the leaf chlorophyll content in flag leaves is closely related to the degree of phosphorus stress. Identifying major genes/loci associated with chlorophyll content in flag leaves under different phosphorus conditions is critical for breeding wheat varieties resistant to low phosphorus (P). Under normal, medium, and low phosphorus conditions, the chlorophyll content of flag leaves was investigated by a double haploid (DH) population derived from a cross between two popular wheat varieties Jinmai 47 and Jinmai 84, at different grain filling stages. Chlorophyll content of the DH population and parents decreased gradually during the S1 to the S3 stages and rapidly at the S4 stage. At the S4 stage, the chlorophyll content of the DH population under low phosphorus conditions was significantly lower than under normal phosphate conditions. Using a wheat 15K single-nucleotide polymorphism (SNP) panel, a total of 157 QTLs were found to be associated with chlorophyll content in flag leaf and were identified under three phosphorus conditions. The phenotypic variation explained (PVE) ranged from 3.07 to 31.66%. Under three different phosphorus conditions, 36, 30, and 48 QTLs for chlorophyll content were identified, respectively. Six major QTLs <jats:italic>Qchl.saw-2B.1</jats:italic>, <jats:italic>Qchl.saw-3B.1</jats:italic>, <jats:italic>Qchl.saw-4D.1</jats:italic>, <jats:italic>Qchl.saw-4D.2</jats:italic>, <jats:italic>Qchl.saw-5A.9</jats:italic> and <jats:italic>Qchl.saw-6A.4</jats:italic> could be detected under multiple phosphorus conditions in which <jats:italic>Qchl.saw-4D.1</jats:italic>, <jats:italic>Qchl.saw-4D.2</jats:italic>, and <jats:italic>Qchl.saw-6A.4</jats:italic> were revealed to be novel major QTLs. Moreover, the closely linked SNP markers of <jats:italic>Qchl.saw-4D.1</jats:italic> and <jats:italic>Qchl.saw-4D.2</jats:italic> were validated as KASP markers in a DH population sharing the common parent Jinmai 84, showed extreme significance (<jats:italic>P &amp;lt;</jats:italic>0.01) in more than three environments under different phosphorus conditions, which has the potential to be utilized in molecular marker-assisted breeding for low phosphorus tolerance in wheat.</jats:p>

<jats:p>Human activities have increased the possibility of simultaneous warming and drought, which will lead to different carbon (C) allocation and water use strategies in plants. However, there is no conclusive information from previous studies. To explore C and water balance strategies of plants in response to warming and drought, we designed a 4-year experiment that included control (CT), warming (W, with a 5°C increase in temperature), drought (D, with a 50% decrease in precipitation), and warming and drought conditions (WD) to investigate the non-structural carbohydrate (NSC), C and nitrogen (N) stoichiometry, and intrinsic water use efficiency (iWUE) of leaves, roots, and litter of <jats:italic>Cunninghamia lanceolata</jats:italic>, a major tree species in southern China. We found that W significantly increased NSC and starch in the leaves, and increased NSC and soluble sugar is one of the components of NSC in the roots. D significantly increased leaves’ NSC and starch, and increased litter soluble sugar. The NSC of the WD did not change significantly, but the soluble sugar was significantly reduced. The iWUE of leaves increased under D, and surprisingly, W and D significantly increased the iWUE of litter. The iWUE was positively correlated with NSC and soluble sugar. In addition, D significantly increased N at the roots and litter, resulting in a significant decrease in the C/N ratio. The principal component analysis showed that NSC, iWUE, N, and C/N ratio can be used as identifying indicators for <jats:italic>C. lanceolata</jats:italic> in both warming and drought periods. This study stated that under warming or drought, <jats:italic>C. lanceolata</jats:italic> would decline in growth to maintain high NSC levels and reduce water loss. Leaves would store starch to improve the resiliency of the aboveground parts, and the roots would increase soluble sugar and N accumulation to conserve water and to help C sequestration in the underground part. At the same time, defoliation was potentially beneficial for maintaining C and water balance. However, when combined with warming and drought, <jats:italic>C. lanceolata</jats:italic> growth will be limited by C, resulting in decreased NSC. This study provides a new insight into the coping strategies of plants in adapting to warming and drought environments.</jats:p>

<jats:p>Potato is the most important non-grain food in the world, while late blight caused by <jats:italic>Phytophthora infestans</jats:italic> seriously threatens the production of potato. Since pathogen-associated molecular patterns (PAMPs) are relatively conserved, PAMP-triggered immunity (PTI) can provide durable resistance to late blight for potato. However, knowledge of the regulatory mechanisms of PTI against oomycete pathogens at protein levels remains limited due to the small number of identified proteins. In the present work, changes in the proteome profile of <jats:italic>Nicotiana benthamiana</jats:italic> leaves upon <jats:italic>P. infestans</jats:italic> PAMP induction were examined using the SWATH-MS (sequential windowed acquisition of all theoretical mass spectra) approach, which provides quantification of protein abundances and large-scale identification of PTI-related proteins. A total of 4401 proteins have been identified, of which 1429 proteins were differentially expressed at least at one time point of 8, 12, 24 and 48 h after PAMP induction, compared with the expression at 0 h when immediately after PAMP induction. They were further analyzed by expression clustering and gene ontology (GO) enrichment analysis. Through functional verification, six novel DEPs of 19 candidates were proved to be involved in PTI responses, including mitochondrial phosphate carrier protein (MPT) 3, vesicle-associated membrane protein (VAMP) 714, lysophospholipase (LysoPL) 2, ascorbate peroxidase (APX) 1, heat shock 70 kDa protein (HSP) 2 and peptidyl-prolyl cis-trans isomerase FKBP (FKBP) 15-1. Taken together, the time course approach and the resulting large-scale proteomic analyses have enlarged our understanding of PTI mechanisms and provided a valuable resource for the discovery of complex protein networks involved in the resistance response of potato to late blight.</jats:p>

<jats:p><jats:italic>Gelsemium elegans</jats:italic> contains multiple alkaloids with pharmacological effects, thus researchers focus on the identification and application of alkaloids extracted from <jats:italic>G. elegans</jats:italic>. Regretfully, the spatiotemporal distribution of alkaloids in <jats:italic>G. elegans</jats:italic> is still unclear. In this study, the desorption electrospray ionization mass spectrometry imaging (DESI-MSI) was applied to simultaneously analyze the distribution of pharmacologically important alkaloids in different organ/tissue sections of <jats:italic>G. elegans</jats:italic> at different growth stages. Finally, 23 alkaloids were visualized in roots, stems and leaves at seedling stage and 19 alkaloids were observed at mature stage. In mature <jats:italic>G. elegans</jats:italic>, 16 alkaloids were distributed in vascular bundle region of mature roots, 15 alkaloids were mainly located in the pith region of mature stems and 2 alkaloids were enriched in epidermis region of mature stems. A total of 16 alkaloids were detected in leaf veins of mature leaves and 17 alkaloids were detected in shoots. Interestingly, diffusion and transfer of multiple alkaloids in tissues have been observed along with the development and maturation. This study comprehensively characterized the spatial metabolomics of <jats:italic>G. elegans</jats:italic> alkaloids, and the spatiotemporal distribution of alkaloid synthesis. In addition, the results also have reference value for the development and application of <jats:italic>Gelsemium elegans</jats:italic> and other medicinal plants.</jats:p>

<jats:p>Osthole is a natural coumarin compound which isolated from <jats:italic>Cnidium monnieri (L.)</jats:italic> Cusson, has extensive pharmacological activities and could be used as a leading compound for drug research and development. In a continuous effort to develop new acetylcholinesterase inhibitors from natural products, eighteen osthole esters were designed, synthesized, and confirmed by <jats:sup>1</jats:sup>H NMR, <jats:sup>13</jats:sup>C NMR and HRMS. The anti-AChE activity of These derivatives was measured at a concentration of 1.0 mol/mL <jats:italic>in vitro</jats:italic> by Ellman's method, and the result showed that 4m and 4o had moderate inhibitory activities with 68.8% and 62.6%, respectively. Molecular docking study results further revealed AChE interacted optimally with docking poses 4m and 4o. Network pharmacology also predicted that compound 4m could be involved in Ras signaling pathway, which made it a potential therapeutic target of AD.</jats:p>

<jats:p>High temperature (HT) during grain filling had adverse influences on starch synthesis. In this study, the influences of HT on resistant starch (RS) formation in rice were investigated. Most genes in <jats:italic>ssIIIa</jats:italic> mutants especially in RS4 were upregulated under Normal Temperature (NT) while downregulated under HT when compared with those of wild parent R7954. <jats:italic>ssIIIa</jats:italic> mutants had higher RS content, more lipid accumulation, higher proportion of short chains of DP 9–15, and less long chains of DP ≥37. <jats:italic>ssIIIa</jats:italic> mutation exacerbated the influences of HT on starch metabolite and caused larger declines in the expression of <jats:italic>BEI</jats:italic>, <jats:italic>BEIIa</jats:italic>, <jats:italic>BEIIb</jats:italic>, and <jats:italic>SSIVb</jats:italic> when exposed to HT. HT reduced the contents of total starch and apparent amylose significantly in wild type but not in mutants. Meanwhile, lipids were enriched in all varieties, but the amounts of starch–lipid complexes and the RS content were only heightened in mutants under HT. HT led to greatest declines in the amount of DP 9–15 and increases in the proportion of fb3 (DP ≥37); the declines and increases were all larger in mutants, which resulted in varied starch crystallinity. The increased long-chain amylopectin and lipids may be the major contributor for the elevated RS content in mutants under HT through forming more starch–lipid complexes (RSV).</jats:p>

<jats:p>AMMONIUM TRANSPORTER/METHYLAMMONIUM PERMEASE/RHESUS (AMT) family members transport ammonium across membranes in all life domains. Plant AMTs can be categorized into AMT1 and AMT2 subfamilies. Functional studies of AMTs, particularly AMT1-type, have been conducted using model plants but little is known about the function of AMTs from crops. Sugarcane (<jats:italic>Saccharum</jats:italic> spp.) is a major bioenergy crop that requires heavy nitrogen fertilization but depends on a low carbon-footprint for competitive sustainability. Here, we identified and functionally characterized sugarcane <jats:italic>ScAMT2;1</jats:italic> by complementing ammonium uptake-defective mutants of <jats:italic>Saccharomyces cerevisiae</jats:italic> and <jats:italic>Arabidopsis thaliana</jats:italic>. Reporter gene driven by the <jats:italic>ScAMT2;1</jats:italic> promoter in <jats:italic>A. thaliana</jats:italic> revealed preferential expression in the shoot vasculature and root endodermis/pericycle according to nitrogen availability and source. Arabidopsis quadruple mutant plants expressing <jats:italic>ScAMT2;1</jats:italic> driven by the CaMV35S promoter or by a sugarcane endogenous promoter produced significantly more biomass than mutant plants when grown in NH<jats:sub>4</jats:sub><jats:sup>+</jats:sup> and showed more <jats:sup>15</jats:sup>N-ammonium uptake by roots and nitrogen translocation to shoots. In <jats:italic>A. thaliana</jats:italic>, ScAMT2;1 displayed a K<jats:sub>m</jats:sub> of 90.17 µM and V<jats:sub>max</jats:sub> of 338.99 µmoles h<jats:sup>-1</jats:sup> g<jats:sup>-1</jats:sup> root DW. Altogether, our results suggest that ScAMT2;1 is a functional high-affinity ammonium transporter that might contribute to ammonium uptake and presumably to root-to-shoot translocation under high NH<jats:sub>4</jats:sub><jats:sup>+</jats:sup> conditions.</jats:p>

<jats:p>Object detection is a vital research direction in machine vision and deep learning. The object detection technique based on deep understanding has achieved tremendous progress in feature extraction, image representation, classification, and recognition in recent years, due to this rapid growth of deep learning theory and technology. Scholars have proposed a series of methods for the object detection algorithm as well as improvements in data processing, network structure, loss function, and so on. In this paper, we introduce the characteristics of standard datasets and critical parameters of performance index evaluation, as well as the network structure and implementation methods of two-stage, single-stage, and other improved algorithms that are compared and analyzed. The latest improvement ideas of typical object detection algorithms based on deep learning are discussed and reached, from data enhancement, <jats:italic>a priori</jats:italic> box selection, network model construction, prediction box selection, and loss calculation. Finally, combined with the existing challenges, the future research direction of typical object detection algorithms is surveyed.</jats:p>