To investigate the effects of different nitrogen applications on the growth and leaf nutrient uptake of Ochroma lagopus plantations,one-and a-half-year-old O.lagopus trees were used as experimental materials.Five treatments set up:0(N0),50 kg·hm-2 urea(N1),100 kg·hm-2 urea(N2),50 kg·hm-2 slow-release nitrogen fertilizer(PCU1),and 100 kg·hm-2 slow-release nitrogen fertilizer(PCU2);tree height,diameter at breast height(DBH),and leaf carbon(C),nitrogen(N),phosphorus(P),chlorophyll,and non-structural carbohydrates(NSC)contents were measured.The results were as follows:(1)Compared with the N0 treatment,tree height,DBH,chlorophyll a,chlorophyll b,and chlorophyll(a+b)contents were significantly increased by 28.66％,50.72％,50.17％,50.71％,and 50.25％,respectively,under the N2 fertilization treatment(P＜0.05).(2)Compared with the N0 treatment,leaf N content significantly increased by 60.16％(P＜0.05)under the N2 fertilization treatment;P content showed a decreasing trend.Under the N0 treatment,leaf N/P＜14,indicating that O.lagopus growth was limited by N element.After nitrogen addition,N/P＞14,indicating that nitrogen fertilization altered the N-element limitation on O.lagopus growth.(3)Compared with the N0 treatment,leaf soluble sugar and NSC contents were significantly increased by 78.98％and 52.49％,respectively,under the N2 fertilization treatment(P＜0.05).(4)Under urea application,the leaf soluble sugar content showed significant positive correlations with N content,C/P,and N/P,and a significant negative correlation with P content;under slow-release fertilizer application,the leaf starch content showed a significant negative correlation with P content and a significant positive correlation with N/P;under nitrogen application,the leaf soluble sugar and starch contents showed significant positive correlations with N content and N/P.(5)The phenotypic plasticity indices for leaf N,N/P,C/P,soluble sugar content,and soluble sugar/starch were all relatively high.The cumulative variance contribution rates of principal component 1(PC1)and principal component 2(PC2)were 66.3％.In summary,nitrogen addition significantly promotes the growth of O.lagopus and leaf nutrient absorption,with the N2 fertilization treatment yielding the best results;nitrogen addition alleviates the limiting effect of nitrogen on O.lagopus growth;O.lagopus promotes growth by increasing chlorophyll content,improving leaf utilization efficiency of nitrogen and phosphorus,and thereby altering the distribution of leaf soluble sugar and starch contents.
The Xisha Islands are a group of tropical coral islands in the northwest of the South China Sea. In these islands, the natural environment is unique and harsh, the biodiversity is low, and the ecosystem is extremely fragile. Threat from pernicious plants is one of the important factors for vegetation degradation in the Xisha Islands. It is necessary to investigate the pernicious plant species and their distribution, and the extent of harm in the Xisha Islands. In this research, field investigation on the 24 islands with vegetation in the Xisha Islands was conducted, and the species composition, distribution, growth characteristics and hazard degree of pernicious plants were comprehensively investigated and analyzed in combination with relevant literature and evaluation system. The results were as follows:(1)There were 26 species of pernicious plants belonging to 20 genera and 10 families in the Xisha Islands, of which the number of plant species belonging to four families of Asteraceae, Fabaceae, Verbenaceae and Lauraceae, accounted for 53.8% of the total number species of pernicious plants.(2)According to their growth, distribution, and hazard degree, pernicious plants could be classified into three hazard levels. The Level 1 of pernicious plants included Cassytha filiformis, Chromolaena odorata, Wollastonia biflora, Leucaena leucocephala, Bidens pilosa and Tridax procumbens, mainly distributed in Yongxing Dao, Dong Dao, Chenhang Dao, and Shanhu Dao.(3)The severity of pernicious plants was closely related to the total number of plant species and area of the island. The life form of pernicious plants in the Xisha Islands was mainly terrestrial herbs, accounting for 57.7%. The pernicious plants mainly came from the Americas, with a similar proportion of natural spread, unintentional introduction, intentional introduction sources. Based on the above results, it is suggested to conduct long-term monitoring of pernicious plants in the Xisha Islands, and formulate scientific prevention and control strategies for pernicious plants that have caused serious harm, including strengthening inspection and quarantine, physical removal, chemical control, alternative control, and publicity and education, etc. The research results provide important basic data, scientific and technological support for the protection, health and sustainable development of the vegetation and ecosystems in the Xisha Islands.
To study the correlation between endogenous hormone content and physiological and biochemical characteristics and somatic embryogenic capacity for different cell lines of Pinus elliottii,seven cell lines induced by immature seeds of P.elliottii were used as materials.The phenotype and cellular structure were observed,and the contents of endogenous hormones,soluble protein,soluble sugar,starch and antioxidant enzyme activities were determined,followed by the maturation culture of five selected cell lines.In order to explore the characteristic index values that affect the embryogenic capacity of cell lines,so as to identify the embryogenic capacity of cell lines with strong embryogenic capacity in the early stage,and provide technical reference for optimizing the somatic embryogenesis and improving the somatic embryo induction rate of P.elliottii.Data analysis involved analysis of variance(ANOVA),Duncan multiple range test,and pearson correlation analysis.The results were as follows:(1)Different cell lines differed in cytological observation,among which the V30 cell line had obvious and more embryonal-suspensor mass(ESM),indicating the V30 line was a strong embryonic line.(2)The endogenous hormone content was significantly and different among cell lines,with a significant positive correlation among abscisic acid(ABA),trans-zeatin riboside(ZR)and cell lines,a significant negative correlation among indoleacetic acid(IAA)content and cell lines,no significant difference among gibberellic acid(GA3)and no significant correlation among GA3 and cell lines.(3)The soluble protein content,soluble sugar content,starch content,peroxidase(POD),superoxide dismutase(SOD),and catalase(CAT)activity were significantly different among cell lines,but showed no obvious correlation with the embryogenic ability of cell lines.(4)Based on the embryogenesis of the cell line and the number of mature embryos,the V30 cell line had a high somatic embryogenesis potential.In conclusion,the somatic embryogenic capacity of the P.elliottii cell line is significantly correlated with the endogenous hormone content,which can provide reference for improving the embryogenic capacity of cell lines and optimizing the maturation conditions of somatic embryos by regulating hormone levels,and also offers technical reference for optimizing somatic embryogenesis and improving the somatic embryo induction rate in P.elliottii.
To explore the community niche characteristics,interspecific relationships and community stability of secondary tropical rainforest in the main stream of the Nandu River,and to reveal its community structure,succession status and trend,21 main species in the tree and shrub layer of the community were studied.Niche width,niche similarity and niche overlap were used to analyze niche characteristics.Spearman coefficient,chi-square(x2)statistic,association coefficient and matching coefficient were used to analyze the interspecific association relationship of the community.The stability of the community was determined by the improved M.Godron stability measurement method.The results were as follows:(1)Heptapleurum heptaphyllum had the highest importance value,and Aporosa dioica had the largest niche width.The total niche similarity and overlap among these main species were generally low,among which Machilus chinensis-Eurya nitida had the highest niche similarity and overlap index(0.69 and 0.87,respectively).(2)The overall association of the main species was a significant positive association,but the significant rate of association test between species pairs was 3.81％.(3)The intersection point of the fitted curve with line segment y=100-x was(39.80,60.20),and the Euclidean distance from the stable point(20,80)was 28.00,which indicates that the community of the secondary tropical rainforest along the main stream of the Nandu River is unstable.In conclusion,the secondary tropical rainforest of the main stream of the Nandu River is in the key stage of transition from pre-successional to mid-successional.In order to maintain and enhance the stability of the community of the secondary tropical rainforest,we should take measures to close hillsides to facilitate for afforestation and reduce human disturbance.The study provides the data basis for promoting the protection and restoration of secondary tropical rainforests and enhancing the stability of watershed ecosystems.
Litter is an important part of forest productivity,and its productivity and stoichiometric ratio(high N and low C∶N,C∶P and N∶P,which facilitate litter decomposition)are vital in regulating soil carbon dynamics through decomposition rate modulation and nutrient release optimization.Although mixed-species plantations are known to significantly alter litter production and soil carbon sequestration compared with monocultures,but how these mixing effects change across different stand age stages remains poorly understood.The objective of this study was four pure Pinus massoniana plantation with different stand ages(25,36,46 and 63 years old)and their corresponding mixed plantations with Castanopsis hystrix.We measured litter production,litter stoichiometric ratio,and soil carbon storage to assess how mixing broad-leaved tree species with pure Pinus massoniana affects these factors across different stand ages.The results were as follows:(1)Tree species mixing significantly increased litter production in mature forests(36 years old).The positive mixing effect on litter production mainly existed in near-mature forests(25 years old)and mature forests(36 years old).Consequently,the litter N content gradually increased with increasing stand age,whereas the P content firstly increased and then decreased.Except for the mature forest(46 years old),mixed plantations had lower C∶N than pure plantations.In over-mature forests(63 years old),we observed maximal mixing effects on litter N content and N∶P but minimal effects on C∶N.(2)Mixing also promoted an increase in soil carbon storage for most stand ages,particularly in the 0-60 cm soil layer.We also observed that the over-mature forest exhibited maximal mixing effect values in each soil layer.(3)Spearman's correlation analysis showed strong association between mixing-influenced soil carbon storage variations and litter C,N,C∶N and N∶P.Thus,introducing Castanopsis hystrix into pure Pinus massoniana plantations can effectively increase litter production and quality,thereby increasing soil carbon storage and promoting nutrient cycling.Moderately extending the management cycle of mixed plantations is beneficial for maximizing their ecosystem functions.
In order to assess the cold resistence of macadamia and select varieties with strong cold resistance. In this study, eight main cultivated varieties of macadamia in Guangxi were treated at -8 ℃ to determine physiological indices related to cold resistance, including superoxide dismutase(SOD)activity, peroxidase(POD)activity, soluble sugar(SS)content, soluble protein(SP)content, proline(Pro)content, malondialdehyde(MDA)content, relative electric conductivity(REC)and chlorophyll(Chl)content. The cold resistance of macadamia was comprehensively evaluated by correlation analysis, principal component analysis, membership function analysis and cluster analysis. The results were as follows:(1)A total of 10 physiological indices of cold resistance were significantly different under low temperature stress.(2)By principal component analysis, 10 physiological indices were converted into three new physiological indices, with a cumulative contribution rate of 90.194%. Combined with the correlation analysis results, SOD, POD, SS, SP, Pro, Chlb and Chl(a+b)were selected as the main for the identification of cold resistance of macadamia.(3)Based on the results of cluster analysis and D value of comprehensive cold resistance, eight macadamia varieties were divided into three categories according to the strength of cold resistance. The first group had the strongest cold resistance, including ‘Guireyin No. 4', ‘Guire No. 7', ‘HY', and ‘JW'; the second group had moderate cold resistance, including ‘Guire No. 5' and ‘Guire No. 1'; the third group had the weakest cold resistance, including ‘A16' and ‘Guire No. 6'. Among them, ‘Guireyin No. 4' had the strongest cold resistance; while ‘Guire No. 6' had the weakest cold resistance. The observation results of leaf morphology under low temperature stress were consistent with the clustering analysis results. These results provide a theoretical basis for the study of cold resistance of macadamia, which is of great significance for planting macadamia in the cold area of Guangxi and planting in the North of China.
The JAZ(jasmonate ZIM-domain)is a repressor protein in the jasmonic acid signaling pathway,inhibiting the expression of early jasmonic acid response genes by interacting with related transcription factors.To elucidate the characteristics and activity of the HbJAZ1.0 gene promoter,this study used the rubber tree variety'CATAS 7-33-97'as material and analyzed the cis-acting elements and expression activity of the HbJAZ1.0 gene promoter through PCR amplification,PlantCARE software,and Arabidopsis thaliana transgenetic techniques.The results were as follows:(1)A total of 1 501 bp promoter sequence upstream of the HbJAZ1.0 gene was isolated from the genomic DNA of the rubber tree.(2)Several key cis-acting elements had been identified within the HbJAZ1.0 gene promoter,including ABRE for abscisic acid,TCA-element for salicylic acid,as well as ACAT-motif,Box 4,G-box,GT1-motif,TCCC-motif,TCT-motif and chs-CMA1a for light responsiveness.(3)A plant expression vector containing the GUS reporter gene under the control of the HbJAZ1.0 gene promoter had been constructed and transformed it into A.thaliana using Agrobacterium tumefaciens-mediated transformation.Histochemical GUS staining demonstrated extensive expression of the HbJAZ1.0 gene promoter throughout various tissues of Arabidopsis thaliana,including roots,stems,leaves,flowers,and fruits.In conclusion,the results indicate the HbJAZ1.0 gene promoter has a constitutive expression activity and might be regulated by light and various plant hormones.The results of the study may lay the foundation for further study on the function of HbJAZ1.0 gene.
Protein phosphatase 2C(PP2C)play important roles in growth and development, cell cycle regulation, signal transduction, and responses to environmental stress. This study focused on Artemisia desertorum, a highly drought-tolerant and multifunctional plant native to arid desert regions, to investigate the functional role of PP2C2 gene in drought tolerance. Using A. desertorum as the experimental material, the PP2C2 gene was amplified, its sequence was subjected to bioinformatic analysis, and its protein structure was predicted. Additionally, the expression patterns of PP2C2 under various water stress conditions were analyzed, and the regulatory role of the PP2C2 gene in drought stress responses was elucidated. The results were as follows:(1)The PP2C2 gene in A. desertorum contained an open reading frame(ORF)of 1 404 bp, encoding a protein of 467 amino acids. Sequence alignment demonstrated that the gene shared high homology with PP2C genes from other plants, such as Erigeron canadensis.(2)Bioinformatic analysis revealed that the PP2C2 protein was localized in the nucleus, no signal peptide, and was classified as a non-secretory protein. Its secondary structure predominantly consisted of random coils, with strong hydrophilicity, no transmembrane helical region, and multiple potential modification sites.(3)Quantitative real-time PCR(qRT-PCR)analysis showed that the expression of the PP2C2 gene was responsive to varying levels of drought stress. Under drought conditions, its expression exhibited an overall up-regulation trend, while rehydration led to a significant reduction in expression levels. This study preliminarily reveals that the PP2C2 gene plays a significant role in the drought tolerance mechanism of Artemisia desertorum, offering a theoretical reference for further understanding of its drought resistance mechanism and potential application in genetic engineering.
The SAUR(SMALL AUXIN UP RNA)gene family is an important downstream gene family that promotes hypocotyl elongation.However,molecular mechanism by which SAURs are regulated in high temperature-induced hypocotyl elongation remains unclear.Thermomorphogenesis is defined as a series of morphological changes that occur in a mild high temperature range between the optimal temperature and the adverse high temperature in higher plants.High-temperatured-induced hypocotyl elongation is one of the most intensively researched phenomena.In this study,Arabidopsis Col wild type,hy5 mutant,35S::HY5-HA/Col overexpressed plants and tobacco were used as research materials.Inhibitor NPA(N-1-naphthylphthalamic acid)treatment,quantitative RT-PCR,chromatin immunoprecipitation and double luciferase reporter gene assay were used to explore the molecular mechanisms of high temperature regulation of SAUR1/2/3/4.The results were as follows:(1)Auxin was downstream of HY5(ELONGATED HYPOCOTYL 5)in the thermomorphogenesis signaling pathway.(2)HY5 inhibited the transcription of SAUR1/2/3/4 at 20 ℃ and 29 ℃.(3)At normal temperature and high temperature,HY5 bound to the E-box-containing regions of SAUR1/2/3/4 promoter chromatin,and these bindings were inhibited by high temperature.(4)Auxin was required for the regulation of SAUR1/2/3/4 by HY5.In summary,high temperature regulates the transcription of these four genes by affecting the binding strength of HY5 to SAUR1/2/3/4 promoter chromatin,and this regulatory process requires auxin.This study provides new insights into the molecular mechanisms of hypocotyl elongation downstream genes regulated by high temperature.
In order to understand the mechanism of exogenous methyl jasmonate(MeJA)and chemical fertilizer reduction in reducing continuous cropping strawberry obstacles from the perspective of antioxidant systems such as ascorbic acid-glutathione(AsA-GSH)cycle,this study planted'Hongyan'strawberry in soil that had been used for continuous cropping of strawberry for four years,and measured the nitrate reductase(NR)activity,nitric oxide(NO)content,as well as the non-enzymatic antioxidant content and related enzyme activity of the AsA-GSH cycle.The results were as follows:(1)Under the condition of conventional chemical fertilizer application,exogenous MeJA significantly increased the NO content in continuous cropping strawberry by 35.31％,significantly decreased the AsA content by 19.70％,significantly decreased the ascorbic acid peroxidase(APX)activity by 6.60％,significantly increased the economic yield by 6.41％,and significantly increased biomass by 7.71％.However,it did not significantly affect NR activity,GSH content,and glutathione reductase(GR)activity.(2)Under the condition of halving the amount of chemical fertilizer,exogenous MeJA significantly increased the NO content of continuous cropping strawberry by 53.31％,significantly reduced the AsA content by 45.45％,significantly reduced APX activity by 9.23％,significantly increased economic yield by 6.66％,and significantly increased biomass by 8.17％.However,it did not significantly affect NR activity,GSH content,or GR activity.(3)Under clear water spray,chemical fertilizer reduction significantly increased the NO content,AsA content,and APX activity of continuous cropping strawberry by 27.34％,86.11％,and 6.88％,respectively.However,it did not significantly affect NR activity,GSH content,or GR activity,as well as economic yield and biomass.(4)Under the condition of spraying MeJA,chemical fertilizer reduction significantly increased the NO content and AsA content in continuous cropping strawberry by 44.27％and 26.42％,respectively.However,it did not significantly affect NR activity,GSH content,APX activity,or GR activity,as well as economic yield and biomass.In summary,both exogenous MeJA and chemical fertilizer reduction have no significant effect on the GSH content and GR activity of continuous cropping strawberry.However,exogenous MeJA can alleviate the stress response of strawberry plants to continuous cropping and high salt stress,thus reducing the AsA content and APX activity.Chemical fertilizer reduction significantly increases the AsA content and APX activity,indicating that continuous cropping strawberry may mainly rely on the AsA pathway to cope with continuous cropping obstacles and excessive fertilizer stress.
Nuclear suspension is an important foundation for a variety of molecular biology researches.To effectively prepare the nuclear suspensions of Norway spruce(Picea abies)proembryogenic masses(PEM),PEMs of Norway spruce embryonic cell lines PaVⅢ,PI3,and PI5 were used as the materials for nucleus extraction with six lysis buffers:(LB01,Otto's,Galbraith's,GPB,WPB and Tris·MgCl2).Based on detecting DNA content by flow cytometry,the quantity and quality of the nucleus suspensions were evaluated to screen for the optimal extraction buffer.Further,the stability of optimal buffer and the integrity of nucleus were measured.The results were as follows:(1)Compared with the other lysates,the number of nuclei obtained of PaV Ⅲ line PEMs from LB01 was the highest,with lower amount of cell debris.(2)In addition,coefficients of variation(CVs)of G0/G1 and G2/M nuclei,obtained from LB01,were not more than 5％.The CVs were relatively low.(3)The nuclei of different lines PEMs were extracted by LB01.There was no significant difference in the number of nuclei extracted and the proportion of cell debris among the different lines.(4)The nuclear membrane of most cells maintained in a high integrity when the nuclei of Norway spruce PEMs were extracted via LB01 through morphology investigation.To sum up,compared with other buffers,LB01 is the optimal one for Norway spruce PEMs nucleus extraction,which may provide reference for nucleus extraction from gymnosperms.
Acquiring sufficient nitrogen(N)to meet requirements for growth is a major challenge for epiphytes living in nutrient-poor canopy habitats.Cyanolichens(lichens that contain cyanobacterial symbionts)can function as the primary participants in biological nitrogen fixation in many terrestrial ecosystems due to their excellent N-fixing ability,however,it remains unclear whether fixed N from epiphytic cyanolichens can be transferred to neighboring epiphytes.To assess the N contribution of cyanolichens to epiphytes,this study focused on epiphytic ferns,bryophytes and coexisting cyanolichen Lobaria retigera in subtropical montane moist evergreen broad-leaved forests of the Ailao Mountains,Yunnan Province,southwest China.Using 15N natural abundance analysis,the N transfer between the cyanolichens and epiphytes and its impact on the nutrients of epiphytes were investigated.The results were as follows:(1)Cyanolichens significantly transferred N to epiphytes,contributing 26.18％and 35.15％of N to bryophytes and ferns,respectively.(2)The presence of cyanolichens enhanced the ability of phosphorus(P)acquisition in bryophytes,thereby significantly reducing their N:P ratio,while no significant response was observed in ferns.(3)N transfer from cyanolichens to ferns was primarily influenced by the growth direction of the cyanolichens and the diameter at breast height of the host tree,while N transfer to bryophytes was mainly affected by the growth direction and coverage of the cyanolichens.In conclusion,cyanolichens play a crucial role in supplying N to coexisting epiphyte communities and alleviating N limitation in subtropical forests.This study provides evidence for understanding the formation and maintenance of epiphyte biodiversity in more stressful canopy habitats.
To identify the key temperature and precipitation factors influencing the growth of Pinus sylvestris var.mongolica at different stand ages,this study focused on middle-aged(33 a),mature(48 a),and overmature(64 a)P.sylvestris var.mongolica stands in Zhanggutai,Liaoning Province,and analyzed the growth patterns(basal area increment,BAI)of these stands during 2003-2022.In addition,the Climwin model was used to determine the temperature and precipitation seasonal windows with the strongest influence on growth at different stand ages.The results were as follows:(1)The BAI of the three stands significantly increased from 2003 to 2022.(2)The current July-August mean temperature had the strongest influence on the growth of middle-aged stand.When the July-August mean temperature reached 23.7 ℃,the growth-climate relationship of middle-aged stand turned from positive to negative;precipitation from last November to current May showed the strongest impact on both middle-aged and mature stands.The thresholds of precipitation at which the growth-climate relationship of middle-aged and mature stands shifted from positive to negative were 124 mm and 122 mm,respectively.(3)Temperature had no significant impact on the growth of mature stand;conversely,the temperature in the current July and the precipitation from last August to current May were significantly positively correlated with the growth of overmature stand.(4)Precipitation was proved to be more important than temperature across all stand ages,with its relative importance increasing as the stands aged.Therefore,in the context of a warming and drying climate trend,developing forest management strategies that consider water balance and vary with stand age will facilitate the growth of P.sylvestris var.mongolica plantations.
Estimating gross primary productivity(GPP)of vegetation is essential for exploring the flow and storage of carbon in terrestrial ecosystems and helps to explain the factors influencing global climate change.Remote sensing GPP models are important tools for simulating GPP at regional and global scales.In order to clarify the applicability of two remote sensing GPP models,TG and VI,to two typical forests in the central subtropics as well as the simulation effects of different model parameter calibration methods,the present study was conducted to calibrate the sensitive parameters of the TG and VI models based on the ground-based meteorological data and MODIS data using flux-tower measured GPP at both annual and seasonal scales,and then the GPPs of the regenerated evergreen broad-leaved forest and eucalyptus plantation in the central subtropics were simulated,and the simulation accuracies of the TG and VI models in these two ecosystems were compared and analyzed.The results were as follows:(1)The simulation accuracy of the models was improved after parameter calibration,especially in the case of seasonal calibration,the simulation accuracy was significantly better than that of the year-round calibration.(2)The correlation between the input parameters of the TG and VI models and the measured GPP of the two ecosystems was high(R2＞0.70,P＜0.001).(3)The correlation between the simulated and measured GPPs of the TG model was higher than that of the VI model,and the simulation error of the TG model was the smallest in the regenerated evergreen broad-leaved forest ecosystem(|RE|＜2％).In conclusion,both models have the potential to be applied in two typical forests in the central subtropics,and the simulation effect of the TG model is better than that of the VI model.
NAC transcription factors are widely present in plants and unique to plants, which play important roles in regulating plant growth and development, hormone signaling, and the response to adverse stress. In our previous work, a low-temperature-induced NAC gene, KoNAC25(GenBank accession number PP860407), was identified from the genome of the mangrove Kandelia obovata. To investigate whether the KoNAC25 gene of K. obovata is involved in the response to salt stress conditions, this study cloned the KoNAC25 gene from the cDNA of K. obovata leaves via RT-PCR and performed sequence characterization, phylogenetic evolution, subcellular localization, and gene expression analyses. The results were as follows:(1)The open reading frame(ORF)of the KoNAC25 gene was 858 bp in length and encoded 285 amino acids, with a molecular weight of 32.9 kDa and a theoretical isoelectric point of 8.53. KoNAC25 was a hydrophilic protein and contained no signal peptide or transmembrane structure, and its secondary structure was predominantly random coils(58.95%).(2)Amino acid sequence homology alignment showed the N-terminus of the KoNAC25 protein had a NAM superfamily structural domain, which consisted of five conserved substructural domains(ABCDE)and belonged to the NAM subfamily.(3)The phylogenetic tree revealed that the KoNAC25 transcription factor of K. obovata was similar to the transcription factors of Ricinus communis, Manihot esculenta, and Hevea brasiliensis.(4)The subcellular localization test confirmed that the protein was localized in the nucleus, which was consistent with bioinformatics prediction.(5)qRT-PCR analysis result revealed that the expression of the KoNAC25 gene was significantly greater in leaves than in flowers and could be induced to upregulate its expression by NaCl(200 mmol·L-1)and abscisic acid(ABA)(100 μmol·L-1), which peaked under 12 h treatment and 6 h treatment, respectively; however, the expression level of this gene was not induced by salicylic acid(100 μmol·L-1)and methyl jasmonate(100 μmol·L-1). In summary, KoNAC25 is involved in the related regulation of the salt stress response in Kandelia obovata, which provides a reference for further research on the function of KoNAC25 gene and its expression regulatory mechanism under salt stress in K. obovata.
Submergence stress, a major environmental constraint in agriculture, causes oxygen deficiency in plant tissues, thereby impairing plant growth, development, and survival. One notable adaptive response of plants to submergence is the accumulation of anthocyanins — flavonoid pigments with strong antioxidant properties that help mitigate reactive oxygen species(ROS)-induced damage. These compounds also play important roles in stress signaling and metabolic reprogramming. Although enhanced anthocyanin accumulation under submergence has been observed in multiple plant species, the underlying regulatory mechanisms, particularly at the transcriptional level, remain poorly understood. To clarify the molecular mechanism of submergence-induced anthocyanin biosynthesis, this study investigated the role of ERF-Ⅶ(ethylene response factor group Ⅶ)transcription factors in Arabidopsis thaliana. Anthocyanin levels were measured in various genotypes exposed to submergence treatment conditions. In addition, protein-protein interaction assays, including yeast two-hybrid(Y2H)and bimolecular fluorescence complementation(BiFC), were conducted to examine physical interactions between ERF-Ⅶ members and known regulators of anthocyanin biosynthesis. In addition, to elucidate its regulatory pathway, a systematic analysis of the role of RAP2.12 in regulating anthocyanin biosynthesis was conducted at both genetic and molecular levels. The results were as follows:(1)Anthocyanin accumulation under submergence depended on MBW complex, composed of MYB, bHLH, and WD40 proteins, which served as a central regulatory hub in flavonoid biosynthesis.(2)RAP2.12 physically interacted with MYB75, MYB90, and MYB113, and these interactions synergistically activated the expression of anthocyanin biosynthetic genes such as DFR and LDOX, indicating a transcriptional co-activation mechanism.(3)The rap2.2 2.3 2.12 triple mutant exhibited reduced sensitivity to submergence-induced anthocyanin accumulation, while (MA)RAP2.12-HA overexpression lines showed hypersensitivity, indicating that RAP2.12 promotes anthocyanin biosynthesis under submergence and acts as a positive regulator in this stress-adaptive pathway.(4)Genetic analysis revealed that the regulatory function of RAP2.12 was primarily dependent on MYB transcription factors, as RAP2.12 alone could not activate downstream gene expression in the absence of functional MYB proteins. In conclusion, RAP2.12 regulates anthocyanin biosynthesis and accumulation in A. thaliana seedlings under submergence stress by physically interacting with MYB75. It enhances the transcriptional activity of the MBW complex, thereby promoting the expression of key structural genes in the anthocyanin biosynthetic pathway. These findings expand our understanding of the roles of ERF-Ⅶ transcription factors in plant adaptation to hypoxic environments. Furthermore, this work provides novel insights into how environmental signals are integrated through transcriptional regulators to coordinate secondary metabolism and stress responses. It also provides a theoretical basis for understanding the molecular mechanism of plant response submergence stress and crop breeding.
Climate warming affects the plant-pollinator interactions by altering flowering phenology,reproductive allocation,and floral traits of plants,which ultimately leads to changes in reproductive success of plants.Alpine regions are the most sensitive areas to global warming.To explore the ecological effects of temperature increase on the plant reproductive process in these regions,this study focused on Delphinium caeruleum,a typical alpine plant species in the alpine meadows of the Qinghai-Tibet Plateau.By using an open top chamber(OTC)for warming treatment,the effects of warming on the flowering phenology,biomass allocation patterns,typical floral characteristics,and reproductive success of D.caeruleum were investigated,as well as changes in pollinator visiting behavior and pollination efficiency.The results were as follows:(1)Warming advanced the flowering phenology of D.caeruleum and significantly shortened individual flowering duration and floral longevity.(2)After warming,the resource investment to vegetative growth increased,resulting in an increase in plant height.However,the reproductive allocation decreased,leading to reductions in flower diameter,nectar spur length,pollen vitality and nectar volume.(3)The changes in floral traits after warming resulted in shortened visitation duration and reduced pollen deposition per visit by its only effective pollinator,Bombus sushikini,which consequently decreased pollination efficiency and ultimately exerted negative impacts on reproductive success.This study reveals the evolution of reproductive characteristics of D.caeruleum and its altered interactions with pollinators under global climate warming,providing a reference for clarifying the ecological effects of climate change on plant reproductive progresses.
Glucose is not only the basic energy source for organisms but also serves as a precursor in various synthetic metabolic processes. Glucose transport proteins(GLUTs)can regulate glucose levels within organisms and play a crucial role in maintaining glucose homeostasis. Currently, the functions of the GLUT family in rubber trees(Hevea brasiliensis)and their roles in key biological processes such as sugar homeostasis and latex regeneration remain unclear. Therefore, this study employed bioinformatics methods to identify GLUTs in rubber trees and systematically analyzed the physicochemical properties, protein structures, conserved motifs, phylogenetic development, cis-acting element structural features, and gene expression patterns of the gene family members. The results were as follows:(1)A total of 31 members of the HbGLUTs family members(HbGLUT1-HbGLUT31)were identified, all located in the cell membrane, with the number of transmembrane domains ranging from 9 to 24(both HbGLUT1 and HbGLUT2 contained 24 transmembrane domains), and the secondary structure was primarily composed of α-helix.(2)Evolutionary analysis revealed that HbGLUTs were functionally similar to human GLUTs in terms of classification. Type I subfamily members(such as HbGLUT8 and HbGLUT15)had conserved hexose transport functions and maintained latex production homeostasis by rapidly supplementing glucose during latex regeneration; it is speculated that Type Ⅱ and Type Ⅲ subfamily members evolved diverse transport capabilities for substrates such as fructose and myo-inositol. Among them, Type Ⅲ subfamily members(such as HbGLUT3, HbGLUT17, HbGLUT18)were highly expressed in various tissues, and their promoters contained stress-related elements, indicating their involvement in plant stress responses.(3)Tissue-specific expression analysis showed that HbGLUTs were generally expressed at low levels in latex, but some genes of Type I subfamily were crucial for latex regeneration. Additionally, several members(such as HbGLUT21 and HbGLUT28, etc.)were highly expressed specifically in flowers, supporting the high energy requirements of the reproductive process. This study provides important clues for elucidating the functions of HbGLUTs in latex regeneration and stress responses, laying a foundation for further research on sugar transport proteins in rubber trees.
Sphingomyelin phosphodiesterase(SMPD)plays a crucial role in the sphingolipid metabolism process by hydrolyzing sphingomyelin into phosphatidylcholines and ceramides.To investigate the functions related to drought tolerance and high-temperature tolerance of an SMPD gene(RcSMPD)in the strongly desiccation-tolerant plant Racomitrium canescens,quantitative real-time PCR(qPCR)was employed to detect the expression of RcSMPD under dehydration stress and high-temperature treatments.The coding sequence of RcSMPD was cloned,and bioinformatics analysis was carried out to predict the protein encoded by RcSMPD.Furthermore,transgenic Arabidopsis thaliana lines overexpressing RcSMPD were constructed to evaluate the drought tolerance and high-temperature tolerance of RcSMPD.The results were as follows:(1)RcSMPD was found to respond to the dehydration stress and high-temperature treatments of Racomitrium canescens to different degrees.(2)RcSMPD had a total of 326 amino acid residues and was a hydrophilic protein.it could be an acidic or neutral SMPD and was predicted to be located in chloroplasts or vacuoles.(3)Compared with wild-type plants,the morphology of the RcSMPD overexpression transgenic Arabidopsis thaliana showed differences,yet there was no significant difference in stress resistance under simulated drought stress and high-temperature stress treatments among the A.thaliana lines.In conclusion,RcSMPD can participate in the response of Racomitrium canescens to dehydration and high-temperature stress.Overexpression of RcSMPD can change the morphology of Arabidopsis thaliana,but has no significant impact on its drought tolerance and high-temperature resistance.
To investigate the relationship between biomass variation in Halophila ovalis and its environmental factors, this study systematically analyzed response relationship of H. ovalis biomass to multiple environmental factors using literature data(1990 — 2025)from the South China coast. Structural equation modeling(SEM)and linear mixed-effects model(LMM)were employed to quantify direct and indirect factors, such as water temperature, salinity, nutrients, suspended solids, and pH on biomass. The results were as follows:(1)Suspended solids in water significantly inhibited biomass accumulation and represented a widespread limiting factor across the region.(2)Water temperature, salinity, and nutrients [including dissolved inorganic nitrogen(DIN)and reactive phosphate in water(PO43-)availability] were key environmental factors leading to biomass differences.(3)Nitrogen and phosphorus nutrients, particularly ammonium nitrogen(NH4+-N), imposed critical constraints on biomass accumulation in each province(region), but dominant factors varied regionally. This study emphasizes that in the future, it is necessary to pay attention to the interaction effects of multi-scale environmental factors and formulate regional adaptive protection strategies based on environmental threshold management. The results of this study provide a scientific basis for the protection and restoration of the seagrass bed of H. ovalis.
