The mature pericarp of Citrus reticulata ' Chachi ' (PCRC) is a traditional Chinese medicine known for its enhanced efficacy through long-term storage and processing. However, the specific mechanisms underlying these enhancements remain unclear. This study employed widely targeted metabolomics, microbial amplicon sequencing, and fermentation assays to investigate the microbiome 's influence on PCRC 's flavonoid profile over 0-19 years of storage. Correlation analysis revealed that the accumulation of polymethoxyflavones (PMFs) was closely linked to specific bacterial and fungal communities. Solid-state fermentation showed that Bacillus subtilis N18-1 enhanced the content of certain PMFs, while Aspergillus tubingensis P21-1 reduced them. Liquid-state assays confirmed that A. tubingensis P21-1 converted nobiletin to 3 ' -demethylnobiletin, and B. subtilis N18-1 further converted this to tangeretin. Combined with genome sequencing and molecular docking, four candidate genes were identified. The catalytic activity verification assays demonstrated that At21-68 and At21-21 catalyze the conversion of nobiletin to 3 '-demethylnobiletin, while Bs18-51 and Bs18-84 catalyze the conversion of 3 ' -demethylnobiletin to tangeretin. These findings highlight the synergistic molecular mechanism by which microorganisms modulate PMFs during PCRC aging, providing insights for optimizing medicinal plant aging through microbial biotransformation.

Plant transcription factors play a crucial role in plant growth, development, and stress resistance. Among them, the NAC transcription factor family is involved in the process of programmed cell death (PCD) during plant growth and development.PCD is involved in the development process of the secretory cavities in the fruit of Citrus reticulata ‘Chachiensis’. During PCD in secretory cavity cells, Ca2+ -dependent and Zn2+ -dependent nucleases collaboratively participate in the degradation of the cell nucleus. However, there are still few studies on the transcription factors that regulate the synergistic action of these two types of nucleases in secretory cavity cells PCD. Therefore, this study investigated the transcription factors involved in the regulation of the synergistic action of Ca²⁺-dependent and Zn²⁺-dependent nucleases which participate in nuclear degradation during the development of secretory cavities in Citrus reticulata ‘Chachiensis’ fruits. In this study, three NAC transcription factors CrNAC2, CrNAC87-like and CrNAC100, were obtained and identified. We found that CrNAC2 had a specific expression peak in the middle initial cell stage of the secretory cavity development. While CrNAC87-like and CrNAC100 were mainly specifically expressed in the late initial cell stage and the lumen-forming stage of the secretory cavity development. These results indicated that three transcription factors were involved in the forming of secretory cavity. Through yeast one-hybrid and dual-luciferase assays, it was found that CrNAC2 negatively regulated the expression of Ca2+ -dependent nuclease CrCAN, whereas CrNAC87-like and CrNAC100 positively regulated the expression of Zn2+ -dependent nuclease CrENDO1. Therefore, we hypothesize that during the development of secretory cavities in Citrus fruits, CrNAC2 negatively regulates the Ca²⁺-dependent nuclease, which mediates limited fragmentation of nuclear DNA in the middle initial cell stage. Subsequently, during the late initial cell stage and the lumen-forming stage, CrNAC87-like and CrNAC100 positively regulate the Zn²⁺-dependent nuclease to completely degrade the nuclear DNA. This study provides additional experimental data for understanding the regulation of nucleases by NAC transcription factors in plant programmed cell death.

Avian pathogenic Escherichia coli (APEC) is an important bacterial infectious disease can pose a threat to poultry and human health, with infected chicks typically exhibiting diarrhea and enteritis. Cinnamon essential oil (CEO) exhibits significant antibacterial, anti-inflammatory and intestinal regulatory properties but limited bioavailability. This study aims to develop an enteric CEO microcapsule and investigate its regulatory effects on anti-inflammatory, and intestinal microenvironment in E. coli-infected chickens, and to reveal the reasons for its superior therapeutic effect on CEO. Different concentrations of enteric CEO microcapsules and CEO were used to treat artificially infected chicken E. coli models, respectively. Cecal content was collected for 16S rRNA gene sequence analysis and metabonomics. Butyric acid content was detected by gas chromatography-flame ionization detection (GC-FID). Inflammatory factors and lipopolysaccharides (LPS) of serum were measured by corresponding ELISA kits. And inflammatory factors in ileum, jejunum and duodenum tissues were detected via quantitative real-time PCR (qRT‒PCR). Pathologic changes in hepatocytes and duodenum were detected by H&E. Dissolution of enteric CEO microcapsules was determined by the paddle method. We observed that the low-dose CEO microcapsule (APEC+MCL) with at least 75 % lower CEO content increased the bioavailability of CEO. This effect was associated with an improvement in the internal environment of the intestinal tract, as in increasing beneficial bacteria and reducing harmful bacteria. Meanwhile, APEC+MCL significantly increased butyric acid content and restored the gut metabolites, improved the level of intestinal inflammatory factors and reduced the inflammatory response, particularly in the duodenum and jejunum segments, with a significant increase in therapeutic effect. Furthermore, APEC+MCL also improved the levels of TNF-α, IL-1β, IL-6, and IL-10 in serum, as well as the liver's protective effect to reduce mortality and increase feed conversion rate (FCR) and average daily gain (ADG). These findings suggest enteric microcapsule system for CEO significantly enhances CEO's therapeutic potential, offering a promising strategy for developing more efficient and cost-effective natural antibacterial treatments for colibacillosis.

Zanthoxylum nitidum is a traditional Chinese herb, but limited information is available concerning its composition and pharmacological effects of essential oils from different parts of Z. nitidum. This study examined the composition and in vitro antioxidant activity of essential oils from different parts of Z. nitidum in China. The results indicate that the highest essential oil extraction rate was obtained from the pericarps (0.42%), primarily consisting of caryophyllene oxide (15.33%), nerolidol 2 (14.03%), and spathulenol (9.64%). This was followed by the leaves (0.21%), stems (0.09%), and roots (0.05%), with the highest content in their essential oils being caryophyllene (27.03%), cadina-1(10),4-diene (25.76%), and benzyl benzoate (17.11%), respectively. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) revealed that, compared with the essential oils from stems and leaves, the essential oils from roots and pericarps showed relatively smaller differences and were usually clustered into one category. The leaf essential oil has the highest in vitro antioxidant activity, followed by the root, pericarp, and stem. This study aims to provide a scientific reference for the rational development and utilization of different parts of Z. nitidum, especially the leaf essential oil.

Calcium (Ca2+)- and zinc Zn2+-dependent nucleases play pivotal roles in plant nuclear DNA degradation in programmed cell death (PCD). However, the mechanisms by which these two nucleases co-participate in PCD-associated nuclear DNA degradation remain unclear. Here, the spatiotemporal expression patterns of two nucleases (CrCAN and CrENDO1) were analyzed qualitatively and quantitatively during PCD in secretory cavity formation in Citrus reticulata 'Chachi' fruits. Results show that the middle and late initial cell stages and lumen-forming stages are key stages for nuclear degradation during the secretory cavity development. CAN and ENDO1 exhibited potent in vitro DNA degradation activity at pH 8.0 and pH 5.5, respectively. Quantitative real-time reverse-transcription polymerase chain reaction, in situ hybridization assays, the subcellular localization of Ca2+ and Zn2+, and immunocytochemical localization showed that CrCAN was activated at the middle and late initial cell stages, while CrENDO1 was activated at the late initial cell and lumen-forming stages. Furthermore, we used immunocytochemical double-labelling to simultaneously locate CrCAN and CrENDO1. The DNA degradation activity of the two nucleases was verified by simulating the change of intracellular pH in vitro. Our results also showed that CrCAN and CrENDO1 worked respectively and co-participated in nuclear DNA degradation during PCD of secretory cavity cells. In conclusion, we propose the model for the synergistic effect of Ca2+- and Zn2+-dependent nucleases (CrCAN and CrENDO1) in co-participating in nuclear DNA degradation during secretory cavity cell PCD in Citrus fruits. Our findings provide direct experimental evidence for exploring different ion-dependent nucleases involved in nuclear degradation during plant PCD.

Zanthoxylum nitidum is a traditional medicinal herb prevalent in China and Southeast Asia. However, despite being a widely cultivated perennial woody plant, an accurate reference and guide for determining the appropriate harvesting age in lacking. This study employed high-performance liquid chromatography (HPLC) and ultraviolet-visible (UV-Vis) spectrophotometry, along with in vitro antioxidant and in vivo anti-inflammatory assays, to comprehensively analyze and compare the roots of Z. nitidum at 1-9 and 14 years. The results indicated a positive correlation between the increase in age and the root biomass. The highest decoction rates were observed in the roots of the 5- (44.08 %) and 4-year-old plants (40.42 %). However, the total alkaloid content (TAC) and the levels of nitidine chloride (NC), chelerythrine, and sanguinarine chloride initially increased but then decreased; their highest contents were 1.49 % (3-year-old), 0.50 % (7-year-old), 0.50 % (5-year-old), and 0.061 % (6-year-old), respectively. The levels of magnoflorine exhibited a trend of 3-year peaks; the respective contents were 0.36 % (3-year-old), 0.30 % (5-year-old), and 0.33 % (14-year-old). The change in the in vitro antioxidant potency composite index correlated with the wave-like trends in the total flavonoid content (TFC) and total phenolic acid (TPA). The indices for 9-, 5-, and 3-year-olds ranked among the top three and were >90. Extracts of Z. nitidum roots demonstrated a therapeutic effect in dextran sulfate sodium-induced ulcerative colitis mice, with that from the roots of 5-year-old plants showing the highest impact. Overall, the Z. nitidum roots of 4-6-year-old plants can be harvested as high-quality raw materials that meet the Pharmacopoeia of the People's Republic of China standards. This study provides scientific references for aspects such as the rational harvesting of Z. nitidum during artificial cultivation, the optimal utilization of land resources, and clinical use.

Some plant essential oils (EOs) are environmentally friendly insecticides because they can kill insects by manipulating the social behaviour of the red imported fire ants. In this study, we found that the main component of cinnamon oil, trans-cinnamaldehyde, which is extracted from the bark and leaves of Cinnamomum loureirii Nees and Cinnamomum cassia Presl, could cause leg-antennal and double-antennal grooming, as well as fighting behaviors in red imported fire ants. In particular, the bark oils not only produced strong fighting behaviour but also accelerated the death of the worker ants. Analysis of the contents of neurotransmitters (octopamine and dopamine) in red imported fire worker ants treated with trans-cinnamaldehyde, the main component of cinna-mon oil, showed that trans-cinnamaldehyde destroyed the antennal receptor structure, causing a decrease in octopamine content and in the ants' ability to recognise their nest mates. Trans-cinnamaldehyde stimulated the synthesis of dopamine, thereby enhancing the aggression of the worker ants. Indeed, the relative mRNA expression levels of two genes needed for dopamine synthesis, tyrosine hydroxylase and DOPA decarboxylase, were significantly upregulated compared with those of the control group (CK) from the beginning of the fight to the peak of the fight. The ratio of octopamine to dopamine reached 1:86 during the peak of the fight. The findings revealed that trans-cinnamaldehyde acts on the nervous system of red imported fire ants to interfere with the behaviour of the workers, thus providing a strategy to control the spread of red imported fire ants using cin-namon EOs.

Vacuolar processing enzymes (VPEs) with caspase-1-like activity are closely associated with vacuole rupture. The destruction of vacuoles is one of the characteristics of programmed cell death (PCD) in plants. However, whether VPE is involved in the vacuole destruction of cells during secretory cavity formation in Citrus plants remains unclear. This research identified a CgVPE1 gene that encoded the VPE and utilized cytology and molecular biology techniques to explore its temporal and spatial expression characteristics during the PCD process of secretory cavity cells in the Citrus grandis 'Tomentosa' fruit. The results showed that CgVPE1 is an enzyme with VPE and caspase-1-like activity that can self-cleave into a mature enzyme in an acidic environment. CgVPE1 is specifically expressed in the epithelial cells of secretory cavities. In addition, it mainly accumulates in vacuoles before it is ruptured in the secretory cavity cells. The spatial and temporal immunolocalization of CgVPE1 showed a strong relationship with the change in vacuole structure during PCD in secretory cavity cells. In addition, the change in the two types of VPE proteins from proenzymes to mature enzymes was closely related to the change in CgVPE1 localization. Our results indicate that CgVPE1 plays a vital role in PCD, causing vacuole rupture in cells during the development of the secretory cavity in C. grandis 'Tomentosa' fruits.

Zingiber zerumbet and Zingiber corallinum are economically valuable species in the genus Zingiber. While Z. corallinum is sexually active, Z. zerumbet adopts clonal propagation, although it has the potential for sexual reproduction. It is unclear so far at which step during the sexual reproduction of Z. zerumbet inhibition occurs, and what are the regulatory mechanisms underlying this inhibition. Here, by comparing with the fertile species Z. corallinum using microscopy-based methods, we show that rare differences were observed in Z. zerumbet up to the point when the pollen tubes invaded the ovules. However, a significantly higher percentage of ovules still contained intact pollen tubes 24 h after pollination, suggesting pollen tube rupture was impaired in this species. Further RNA-seq analysis generated accordant results, showing that the transcription of ANX and FER, as well as genes for the partners in the same complexes (e.g., BUPS and LRE, respectively), and those putative peptide signals (e.g., RALF34), were timely activated in Z. corallinum, which ensured the pollen tubes being able to grow, reorient to ovules, and receipt by embryo sacs. In Z. zerumbet, genes for these complexes were cooperatively suppressed, which would result in the maintenance of PT integrity due to the disruption of RALF34-ANX/BUPS signaling in PT and the failure of PT reception by an active synergid due to the insufficiency of the synergid-harbored FER/LRE complex. Taking the results from the cytological and RNA-seq studies together, a model is proposed to illustrate the possible regulation mechanisms in Z. zerumbet and Z. corallinum, in which the regulations for pollen tube rupture and reception are proposed as the barrier for sexual reproduction in Z. zerumbet.

Background The medicinal material quality of Citrus reticulata ‘Chachi’ differs depending on the bioactive components influenced by the planting area. Environmental factors, such as soil nutrients, the plant-associated microbiome and climatic conditions, play important roles in the accumulation of bioactive components in citrus. However, how these environmental factors mediate the production of bioactive components of medicinal plants remains understudied. Results Here, a multi-omics approach was used to clarify the role of environmental factors such as soil nutrients and the root-associated microbiome on the accumulation of monoterpenes in the peel of C. reticulata ‘Chachi’ procured from core (geo-authentic product region) and non-core (non-geo-authentic product region) geographical regions. The soil environment (high salinity, Mg, Mn and K) enhanced the monoterpene content by promoting the expression of salt stress-responsive genes and terpene backbone synthase in the host plants from the core region. The microbial effects on the monoterpene accumulation of citrus from the core region were further verified by synthetic community (SynCom) experiments. Rhizosphere microorganisms activated terpene synthesis and promoted monoterpene accumulation through interactions with the host immune system. Endophyte microorganisms derived from soil with the potential for terpene synthesis might enhance monoterpene accumulation in citrus by providing precursors of monoterpenes. Conclusions Overall, this study demonstrated that both soil properties and the soil microbiome impacted monoterpene production in citrus peel, thus providing an essential basis for increasing fruit quality via reasonable fertilization and precision microbiota management.

本研究以红腺忍冬嫩叶为外植体材料,探讨对应的最适组织快繁体系,为红腺忍冬种苗组织快繁工厂化生产提供新思路.结果表明,外植体最适消毒时间为8min,最适诱导愈伤组织的培养基配方为:MS+2,4-D4.0mg/L+蔗糖30 g/L,平均诱导率为86.67％.适合红腺忍冬愈伤组织分化出芽的培养基配方为:MS+6-BA 1.0 mg/L+NAA 0.10 mg/L+蔗糖30 g/L,平均出芽率为83.33％.适合红腺忍冬分化芽增殖的培养基配方为:MS+6-BA 1.5 mg/L+NAA 0.05mg/L+蔗糖30g/L,增殖系数为5.42.适合红腺忍冬诱导生根的培养基配方为:1/2MS+NAA0.15mg/L+活性炭0.3 g/L+蔗糖15 g/L,生根率达91.11％.组培苗在V泥炭土:V珍珠岩=3:1的栽培基质中成活率高达100％.

The quality of Chinese medicinal materials depends on the content of bioactive components, which are affected by the environmental factors of different planting regions. In this research, integrated analysis of the transcriptome and metabolome of C. reticulata ‘Chachi’ was performed in two regions, and three orchards were included in the analysis. In total, only 192 compounds were found in fresh peels, and among 18 differentially accumulated flavonoid metabolites, 15 flavonoids were enriched in peels from the Xinhui planting region. In total, 1228 genes were up-regulated in peels from Xinhui, including the CHS and GST genes, which are involved in the salt stress response. Overall, based on the correlation analysis of flavonoid content and gene expression in peels of C. reticulata ‘Chachi’, we concluded that the authenticity of the GCRP from Xinhui may be closely related to the higher content of naringin and narirutin, and the increase in the content of these may be due to the highly saline environment of the Xinhui region.

Main conclusion CgVPE1 is important in the differentiation of TE cells in C. grandis 'Tomentosa' fruits as it may directly affects secondary cell wall construction while participating in PCD. The vacuolar processing enzyme (VPE) plays an important role in both developmental and environmentally inducible programmed cell death (PCD); it was originally identified as a cysteine protease localized in the vacuole to activate and mature vacuolar proteins in plants. Interestingly, we found a VPE called CgVPE1 to be associated with deposition of the secondary cell wall in tracheary element (TE) cells in the pericarp of Citrus grandis 'Tomentosa' fruits. We then used ultrathin sections and the TUNEL assay to verify that PCD is involved in TE development. Furthermore, CgVPE1 was found to be mainly expressed in secretory cavities and TEs in the pericarp of Citrus grandis 'Tomentosa' fruits. Immunolocalization of CgVPE1 in the pericarp indicated that CgVPE1 is mainly distributed in the central large vacuole, endoplasmic reticulum, Golgi vesicles, cytosol, and secondary wall before TE maturation. CgVPE1 appeared earlier in the endoplasmic reticulum and Golgi vesicles of TEs cells. The vesicles containing CgVPE1 near the large central vacuole and secondary wall were observed, respectively. CgVPE1 proteins content in the cytoplasm decreased sharply, while the CgVPE1 content in the secondary cell wall did not change significantly after vacuole rupture. CgVPE1 protein contents in the secondary cell wall were significantly reduced until the TE cells developed into hollow thick-walled cells. Furthermore, labeling of VPE homologues in Arabidopsis thaliana using immunoelectron microscopy with anti-CgVPE1 antibody revealed that VPE homologues were specifically distributed in the secondary cell wall of stem TEs. Overall, these results suggested that CgVPE1 is not only involved PCD during TE cell development; furthermore, it may directly participate in the construction of plant secondary cell walls.

Cinnamomum loureirii is one of the most important medicinal and aromatic plants. It is used by the food, perfumery, cosmetic, and pharmaceutical industries. The objective of this study was to examine the relationships between the chemical composition and antioxidant activity of essential oil (EOs) and ethanol extracts from 10 samples of the bark from C. loureirii trees (6–15 years old). Obtained results showed that C. loureirii bark EO content at 12–15 years old had high oil yields (4.52–5.48%). The major components in the EOs were trans-cinnamaldehyde (50.2–92.9%) and α-copaene (0.5–21.3%). The highest content of trans-cinnamaldehyde in bark EOs was obtained from 10 to 12-year-old trees, while the highest content of α-copaene was obtained at 13–15 years. The highest total phenolic (429.85 and 474.45 mg TAE /g DW) and total flavonoid contents (85.54 and 102.80 mg RE /g e DW) were obtained from the 13- to 14-year-old trees. Our results indicated that the EO and ethanol extract of 13- to 14-year-old bark showed the strongest antioxidant properties. Moreover, GC–MS, PCA and correlation analysis indicated that the changes in α-copaene, beta-caryophyllene, τ-muurolene, γ-muurolene, δ-cadinene and τ-muurolol were positively correlated with the changes in antioxidant activity in oils. Meanwhile, procyanidin B2 and hyperoside were the main contributors to the antioxidant activity of the ethanol extract from C. loureirii bark. This study is the first one that report the antioxidant potential and phenolic profile of C. loureirii plant. These results provide reference information for the rational utilization of C. loureirii resources and the harvest of C. loureirii bark as medicinal materials during the optimal period.

Organic acids and flavonoids are the main active components in Lonicera species. Chlorogenic acid and luteoloside are important components, and their synthesis is regulated in plants by the phenyl-propanoid synthesis pathway. Downstream of the phenylpropanoid synthesis pathway, hydroxycinnamoyl CoA quinate hydroxycinnamoyl transferase (HQT) and flavone synthase (FNS) are critical enzymes that are involved in chlorogenic acid and luteoloside biosynthesis, respectively. In this study, we first determined the dynamic accumulations of chlorogenic acid, luteoloside and other active components in different growth stages of the flower buds of Lonicera fulvotomentosa through HPLC-DAD and then investigated the expressions of the LJHQT and LJFNS gene families by q-RT-PCR. In addition, we also compared the expression levels of HQT and FNS orthologous genes in vari-ous tissues of Lonicera japonica, L. fulvotomentosa, and Lonicera hypoglauca. The results indicated that the chlorogenic acid contents exhibit leaf accumulation that is preferential in L. fulvotomentosa but exhibit bud accumulation that is preferential in L. japonica and L. hypoglauca. The luteoloside contents show preferential leaf accumulation in these three species. Our results suggest that the leaves and buds of these three species are rich in medicinal ingredients, including chlorogenic acid (CGA) and luteoloside, and therefore can be used as a material to extract CGA and luteoloside rather than being wasted. Furthermore, combined with the transcript expression levels of HQTs and FNSs, we explained the species-specific and tissue-specific occurrence of CGA and luteoloside. We analyzed dynamic changes of components and gene expression and demonstrated that the expressions of HQTs and FNSs in these three species are closely related to the synthesis of chlorogenic acid and luteoloside.

Cell expression is coordinated with chloroplast division in diploid and tetraploid Arabidopsis thaliana, polyploidy promoted the expansion of mesophyll cells and chloroplast division in A. thaliana. Cell development and differentiation are always accompanied by cell expansion and chloroplast division in plants, but the relationship between them is still relatively unknown. To confirm the relationship between cell expansion and chloroplast division during the leaf development process of diploid and tetraploid Arabidopsis thaliana, we systematically analyzed the expansion of mesophyll cells and the division of chloroplasts through cytological observation and gene-expression characteristics. As a result, in diploid and tetraploid A. thaliana, there were two peaks in both mesophyll cell expansion and chloroplast division during the leaf development process. Tetraploid A. thaliana mesophyll cells were larger and contained more chloroplasts than diploid A. thaliana mesophyll cells, which indicated that cell division and cell expansion were coordinated with chloroplast division in A. thaliana and that polyploidy further promoted mesophyll cell expansion and chloroplast division.

Caspase-3 is the crucial executor caspase of apoptosis in mammalian cells, which is essential for chromatin condensation and DNA fragmentation. Although plants have no caspase-3 homologs, PBA1 acts as a plant caspase-3-like enzyme in plant programmed cell death (PCD). PCD occurs during the formation of secretory cavities in Citrus fruits; hence, secretory cavities could be utilized as a new cell biology model for investigating the regulatory mechanisms of plant PCD. To further study the association between PBA1 and PCD during secretory cavity development in Citrus fruits, CgPBA1 was identified in the fruit of Citrus grandis ‘Tomentosa’. The temporal and spatial expression of CgPBA1 during secretory cavity development were analyzed using quantitative real-time PCR and in situ hybridization, and the morphological changes in the apoptotic cell nuclei were observed using TUNEL assay and ultra-thin section technology. The results revealed that the full-length cDNA of CgPBA1 contains a 711 bp ORF that encodes a putative protein containing 236 amino acid with a proteasome-β-6 functional domain that belongs to the Ntn hydrolase super family. CgPBA1 was predominantly expressed in the secretory cavities; its expression changes coincided with the morphological changes and DNA fragmentation in apoptotic cell nuclei. The green fluorescent fusion protein of CgPBA1 is also located in the nucleus of tobacco epidermal cells. Based on previous research and the findings of the present study, we speculate that CgPBA1 is a highly functional conserved protein in plants, and it might be involved in nuclear degradation during PCD for secretory cavity formation in C. grandis ‘Tomentosa’ fruits.

The secretory cavity is a typical structure in Citrus fruit and is formed by schizolysigeny. Previous reports have indicated that programmed cell death (PCD) is involved in the degradation of secretory cavity cells in the fruit, and that the spatio-temporal location of calcium is closely related to nuclear DNA degradation in this process; however, the molecular mechanisms underlying this Ca2+ regulation remain largely unknown. Here, we identified CgCaN that encodes a Ca2+-dependent DNase in the fruit of Citrus grandis 'Tomentosa', the function of which was studied using calcium ion localization, DNase activity assays, in situ hybridization, and protein immunolocalization. The results suggested that the full-length cDNA of CgCaN contains an ORF of 1011 bp that encodes a protein 336 amino acids in length with a SNase-like functional domain. CgCaN digests dsDNA at neutral pH in a Ca2+-dependent manner. In situ hybridization signals of CgCaN were particularly distributed in the secretory cavity cells. Ca2+ and Ca2+-dependent DNases were mainly observed in the condensed chromatin and in the nucleolus. In addition, spatio-temporal expression patterns of CgCaN and its protein coincided with the time-points that corresponded to chromatin degradation and nuclear rupture during the PCD in the development of the fruit secretory cavity. Taken together, our results suggest that Ca2+-dependent DNases play direct roles in nuclear DNA degradation during the PCD of secretory cavity cells during Citrus fruit development. Given the consistency of the expression patterns of genes regulated by calmodulin (CaM) and calcium-dependent protein kinases (CDPK) and the dynamics of calcium accumulation, we speculate that CaM and CDPK proteins might be involved in Ca2+ transport from the extracellular walls through the cytoplasm and into the nucleus to activate CgCaN for DNA degradation.

针对高校在目前抗击新冠肺炎疫情特殊时期的"停课不停教,停课不停学"要求,华南农业大学生命科学学院植物学教学团队在积极开展线上教学的基础上,充分利用网络课程模式融入德育元素.不断探索线上教学过程中的品德教育,以达到全程、全方位育人,实现德育智育相融合的植物学课程教学新模式.

在“停课不停教,停课不停学”的线上教学过程中,华南农业大学植物学课程重组教学资源,优化教学内容,创新教学活动,利用雨课堂、腾讯课堂等多平台,辅以中国大学慕课资源多形式融合的方式开展线上教学新模式,初步取得了良好的教学效果.