Abstract:Plant apoplast plays an important role in sensing external signals and stress responses. In this study, we used physiological and biochemical, and proteomic methods to analyze the physical and chemical indexes, microstructure, and protein changes in the apoplast fluid of Euonymus japonicus leaves in autumn and winter, and to explore the molecular mechanism of the response in the apoplast fluid of E. japonicus leaves to freezing stress, to provide a basis for the study of plant antifreeze molecular mechanism. The results showed that: (1) the contents of MDA and soluble sugar in the leaves of E. japonicus in winter increased significantly, the activities of SOD and POD increased significantly, the stomatal conductance decreased, and the leaf thickness decreased. (2) The types and contents of proteins in the apoplast fluid of E. japonicus leaves in winter were significantly higher than those in autumn. (3) A total of 838 peptides and 194 proteins were identified in the apoplast fluid of E. japonicus leaves. Compared with autumn, a total of 43 differentially accumulated proteins (DAPs) were screened in the apoplast fluid of E. japonicus leaves in winter, among which 26 DAPs were significantly up-regulated and 17 DAPs were significantly down-regulated. The analysis of protein expression patterns showed that the late embryogenesis abundant (LEA) protein, iron superoxide dismutase (Fe-SOD), peroxidase, and serine carboxypeptidase were highly expressed in winter, suggesting that they may be sensitive to a winter stress response. (4) KEGG enrichment analysis showed that DAPs were mainly related to biological processes such as stress defense, cell wall modification, disease resistance, free radical scavenging, glycerol lipid metabolism, starch and sucrose metabolism, and biosynthesis of secondary metabolites. (5) The results of verification experiments showed that the expression trends of 8 DAPs were consistent with those of their corresponding genes in winter. It was speculated that the proteins accumulated in the apoplast fluid of E. japonicus leaves in winter could enhance the adaptation to the environment by scavenging reactive oxygen species and promoting the production of osmotic regulators such as monosaccharides, oligosaccharides, and free amino acids, and the accumulation of monosaccharides and oligosaccharides in the apoplast may reduce the freezing point by increasing the concentration of apoplast fluid, thereby improving the tolerance of E. japonicus to winter stress.

Abstract:Endo-1,4-β-glucanases (EGases) are involved in editing of plant cell walls and play important roles in tissue elongation, fruit ripening, and abscission. In this study, we cloned an EGases gene PnCel1 from Panax notoginseng by RT-PCR, and analyzed its expression and function. The results showed that: (1) Exogenous methyl jasmonate, salicylic acid, gibberellin, abscisic acid, and ethephon treatment significantly induced the expression level of PnCel1, while the infection of root rot fungi including Fusarium solani and Fusarium oxysporum as well as Alternaria alternata and Fusarium equiseti significantly inhibited its expression level in P. notoginseng. (2) Subcellular localization result showed that PnCel1-GFP fusion protein was localized in the cell wall of onion epidermal cells. (3) The promoter sequence ［(-1)-(-828) bp］ of PnCel1 was cloned through chromosome walking, and a plant expression vector (pBI121-PPnCel1-GUS) of β-glucuronidase driven by PnCel1 promoter was successfully constructed, which was then transferred into Nicotiana tabacum L., and 7 positive transgenic tobacco plants were identified through PCR screening. (4) GUS activity detection indicated that 5 plant hormones can induce promoter activity of PnCel1, including methyl jasmonate, but the transcriptional activity of PnCel1 promoter decreased after infection with 4 pathogens, such as F. solani. And the PnCel1 promoter was also negatively regulated by the P. notoginseng WRKY transcription factor 5/9/12/15/27. (5) Compared with wild-type tobacco, PnCel1-overexpressing transgenic tobacco increased susceptibility to the root rot and decreased lignin content, indicating that PnCel1 may be involved in altering the cell wall structure. The above results indicate that plant hormones can up-regulate the expression of PnCel1 in P. notoginseng roots, while pathogens infection reduces the expression level of PnCel1 and inhibits the PPnCel1 activity. It is speculated that PnCel1 may increase the susceptibility of P. notoginseng to root rot by modification of cell wall structure.

Abstract:Saussurea inversa Raab-Straube is a typical alpine plant, having developed aerenchyma is the most representative structural feature. This study cloned the aerenchyma related gene (ShCTR1) with S. inversa using the homologous cloning and RACE technology, and by means of sequence analysis, phylogenetic analysis, expression analysis and subcellular location analysis, explored the function of the gene and its aerenchyma. The results indicated that: (1) the ShCTR1 gene cDNA was 2 891 bp (NCBI accession number: ON081649) and contains 2 550 bp open reading frame encoding 849 amino acids, the theoretical isoelectric point is 5.90, with the molecular formula C₄₀₆₆H₆₄₁₇N₁₁₅₉O₁₂₆₈S₄₃. It was a hydrophobic protein with no transmembrane structure. (2) Phylogenetic tree analysis showed that S. inversa ShCTR1 had high similarity with CcCTR1 of Cynara cardunculus L., Sequence analysis of non-coding regions identified ShCTR1 containing a large number of photoresponse elements, suggesting that ShCTR1 may be involved in the response to UV stress. (3) Quantitative real-time fluorescence analysis showed that ShCTR1 were expressed in roots, stems and leaves, with the highest expression in roots, and its expression was upregulated under UV, cold and hypoxia stresses, which demonstrated that the ShCTR1 was involved in the response to the above three stresses. (4) Subcellular localization revealed that ShCTR1 was predominantly distributed in the nucleus. It had speculated that ShCTR1 may have an important role in the formation of aerenchyma as well as in response to adversity stress.

Abstract:Salinity is one of the major environmental factors that limit the growth and development of plants worldwide. It has been documented that Na⁺/H⁺ transporters play a crucial role in salt tolerance and the development of plants. In this study, the genome-wide of NHX genes of Casuarina equisetifolia L. were identified and analyzed by bioinformatics method, and the expression of NHX genes in C. equisetifolia under salt stress was detected by qRT-PCR for exploring the biological function of CeqNHX gene family, which laid a theoretical foundation for further research on salt stress mechanism and digging out its resistance genes. The results were summarized as follows: (1) eight CeqNHXs (CeqNHX1-8) were identified, and phylogenetic analyses showed that they belong to three subfamilies (Endo, Vac, and PM), containing 1, 5, and 2 genes, respectively; the number of coding amino acids were 324-546, and the molecular weight were 34.87-60.27 kD, the theoretical isoelectric points were between 6.29-9.08, all of which were hydrophobic amino acids. (2) Gene structure and motif analysis revealed that the number of exons range from 2 to 17, and all contain Na⁺/H⁺ exchange conserved domains; the secondary structure were mainly composed of α-helix and random coil. (3) The promoter regions of CeqNHX genes contain a large number of abiotic stress and hormone response elements, among which, the CeqNHX5 promoter contains 13 kinds and 38 elements. (4) The results of qRT-PCR showed that the CeqNHX genes were expressed differently in different tissues, and most members were mainly expressed in shoots. Under NaCl stress condition, the expression of 8 CeqNHXs in C. equisetifolia was up-regulated to a certain extent. Studies had shown that CeqNHX genes might be involved in the regulation of various hormones and stress responses, and the expression of CeqNHXs was significantly responsive to salt stress, suggesting that CeqNHXs might be related to salt tolerance of C. equisetifolia.

Abstract:In this study, we used the stem bending resistance index to evaluate the resistance to stem lodging of 200 Brassica napus germplasm resources, based on which, one extreme stem lodging resistance material and one non stem lodging resistance material were screened, and then we measured the content of physical and chemical components in the stems of the two materials at maturity, and carried out the transcriptome sequencing analysis of the stems of the two extreme stem lodging resistance materials at the bud stage and full flowering stage, for laying the foundation for genetic improvement of stem lodging resistance in Brassica napus. The results showed that: (1) the stem breaking resistance and stem diameter of 200 Brassica napus germplasm resources were all normal distribution, which belonged to quantitative genetic traits. The extremely non resistant stem fall material GY172 and anti stem fall material GY199, which had similar birth dates, plant types and stem diameter, but significant differences in stem breaking resistance, were screened based on stem breaking resistance and agronomic traits. (2) The phloem of GY199 was denser than that of GY172, while the content of hemicellulose, lignin, neutral detergent fiber and total soluble sugar in the mature stem of GY172 was significantly higher than that of GY199, while the content of cellulose in the mature stem was extremely significantly lower than that of GY199. The content of cellulose in the mature stem was positively correlated with the stem bending resistance of the two materials. (3) Sequencing of stem transcriptome at bud moss stage and full bloom stage revealed that carbon metabolism, carbon fixation, pentose phosphate pathway, amino acid biosynthesis 14 genes (BnaA10G0056100ZS, BnaC08G0455100ZS, BnaA08G0262400ZS, BnaC08G0239700ZS, BnaA07G0362300ZS, BnaC02G0081300ZS, BnaC04G0273000ZS, etc.) were resistant to stem. The expression was significantly up-regulated in metamaterial GY199, these genes may be involved in regulating stem strength traits and serve as candidate genes for stem lodging resistance in rapeseed.

Abstract:Pteridophytes can establish stable symbiotic relationship with arbuscular mycorrhizal fungi (AMF), and significantly enhance their ability to obtain nutrients and resistance to environmental stress. To clarify the AMF colonization characteristics of different pteridophytes, a field survey and sampling of pteridophytes were conducted in Fengkai Heishiding Nature Reserve, Guangdong province. Furthermore, the microscopic and submicroscopic structures of pteridophytes-AMF symbionts were observed and analyzed by light microscope and transmission electron microscope, so as to illustrate the symbiosis characteristics between them. This study can provide valuable information for protecting and exploiting the resources of pteridophytes in South China. The results show that: (1) Hypha was the main infection form, but with the lowest infection rate of arbuscule among different pteridophytes. There were significant differences in the total AMF colonization rate among different pteridophytes. The top three highest colonization rate of AMF was Selaginella japonicum, Lepidopteris sclerotifolia and Pteris chinense, which was significantly higher than other species (P < 0.05). (2) Microstructures observation showed that hypha colonization was the main form of AMF colonization in the roots of all pteridophytes. Hypha could be found in the root cortex cells of all 9 pteridophytes, but not in the stele cells. (3) The hypha of AMF was composed by 2 to 3 layers of thin-walled cells with different thicknesses and shapes (i.e., oval and tabular). (4) AMF hypha and vesicles contained many vacuoles and lipids, which may be regarded as an important pathway for mycorrhiza to store energy. According to this study, we confirmed the widespread colonization of AMF in pteridophytes in terrestrial ecosystems. However, our study also found that the present forms of AMF in different root cells of pteridophytes were significantly different, probably due to plant physiological characteristics and interaction among habitat conditions.

Abstract:We conducted hydroponic experiments in a plant growth chamber to study the effects of exogenous methyl jasmonate (0, 20, 40, 60, 80 and 100 μmol·L^-1 MeJA) on osmotic adjustment capacity in Jatropha curcas seedlings under salt stress (150 mmol·L^-1 NaCl). J. curcas seedlings under normal and salt stress conditions were treated with 0-100 μmol·L^-1 MeJA, and tissue vitality, MDA content, water content, water potential, the concentrations of compatible solutes proline, glycinebetaine, and soluble sugars in leaves of J. curcas seedlings, as well as the activities of the key enzymes Δ¹-pyrroline-5-carboxylate synthetase (P5CS), ornithine aminotransferase (OAT) of proline biosynthesis and the key enzyme betaine aldehyde dehydrogenase (BADH) of glycinebetaine biosynthesis, and the expression level of proline and glycinebetaine biosynthesis-related genes were measured. The results showed that: (1) exogenous MeJA treatment enhanced tissue vitality and water content, but it decreased water potential and MDA content in leaves of J. curcas seedlings under salt stress, and the optimum concentration of MeJA was 60 μmol·L^-1. (2) The application of different exogenous MeJA concentrations increased the contents of proline, glycinebetaine and total soluble sugars, and the 60 μmol·L^-1 concentration had the best effect. Treatment with 60 μmol·L^-1 MeJA significantly enhanced the accumulation of jasmonic acid, proline, and glycinebetaine in J. curcas seedlings under salt stress. (3) The MeJA treatment also clearly raised the activities of BADH, P5CS and OAT, and increased the expression level of the JcBADH, JcP5CS and JcOAT in leaves of J. curcas seedlings under salt stress. However, the MeJA treatment decreased the activity of proline dehydrogenase (ProDH), and inhibited JcBADH expression in leaves of J. curcas seedlings under salt stress. The results showed that exogenous MeJA promoted the accumulation of proline in J. curcas seedlings under salt stress by activating the glutamate and ornithine pathway of proline biosynthesis, especially the ornithine pathway, and inhibiting the proline degradation pathway. Meanwhile, MeJA also activated the biosynthesis of glycinebetaine in J. curcas seedlings. These results indicated that exogenous MeJA treatment can enhance salt tolerance and osmotic adjustment capacity in J. curcas seedlings under salt stress, and osmoregulation is a key factor in MeJA-induced salt tolerance.

Abstract:With the pumpkin variety ‘Yong’ an No.2’ seedlings as the tested material, we adopted the indoor pot experiment, sprayed different concentrations (0, 50, 100, 150, 200 and 300 μmol·L^-1) of melatonin (MT), and then carried out low temperature (10 ℃/7 ℃) stress treatment, to investigate the changes of seedling growth index, relative electric conductivity, antioxidant enzyme activity, osmoregulation substance content and other physiological indexes of stress resistance, and preliminarily explore the physiological mechanism of exogenous melatonin alleviating chilling injury of pumpkin seedlings. The results showed that: (1) under cold stress, pumpkin seedlings showed symptoms of chilling injury such as leaf wilting, water loss, edge chlorosis and discoloration, inward curling, etc. The growth indexes such as plant height, stem diameter, fresh weight, dry weight and strong seedling index and the relative chlorophyll content of leaves were significantly decreased. The relative electric conductivity, MDA content and O₂^-· production rate of leaves were significantly increased by more than 50%, and the activities of superoxide dismutase, peroxidase, catalase, ascorbic acid peroxidase, glutathione reductase, dehydroascorbic acid reductase, soluble sugar, soluble protein and proline were also significantly increased. (2) Compared with the cold stress treatment, the chilling injury symptoms of pumpkin seedling leaves were recovered to different degrees after spraying different concentrations of melatonin on the leaves, and the growth state of 100 μmol·L^-1 MT treatment was the best, and there was no significant difference between the plant morphology and phenotype and the control. The seedling growth index, the relative chlorophyll content of leaves, the activities of six antioxidant enzymes, and the contents of three osmoregulatory substances all increased to varying degrees, and all increased first and then decreased with the increase of MT concentration, and all were the highest under 100 μmol·L^-1 MT treatment. The study found that exogenous melatonin could increase the chlorophyll content of leaves, enhance the activities of antioxidant enzymes, increase the accumulation of osmoregulation substances, significantly reduce the degree of membrane peroxidation caused by low temperature chilling injury, effectively reduce the damage of cold stress on pumpkin seedlings, enhance their ability to resist low temperature, and restore the normal growth of seedlings, and the spraying concentration of 100 μmol·L^-1 had the best effect.

Abstract:To reveal the response strategy of carbon and nitrogen allocation in shrub and herb layers to warming in the alpine shrublands, in this study, we conducted a simulating warming experiment (+1.2 ℃) using the open-top chambers to analyze the influences of warming on carbon and nitrogen allocation among the above- and belowground organs of shrubs and herbs in an alpine shrubland dominated by Sibiraea angustata shrubs on the eastern Qinghai-Tibetan Plateau. The results showed that: (1) warming significantly increased the carbon pool of shrub leaf, coarse roots and fine roots of S. angustata by 18.8%, 7.7% and 139.4%, respectively, as well as the nitrogen pool of shrub fine roots by 153.9%. Warming significantly increased the carbon pool of the above- and belowground parts of herbs by 60.4% and 130.5%, respectively, as well as the nitrogen pool of the above- and belowground parts of herbs by 46.1% and 124.0%, respectively. (2) Warming significantly decreased the carbon allocation proportions of shrub stem and coarse roots by 18.9% and 16.2%, respectively, and significantly decreased nitrogen allocation proportions of shrub leaf, stem and coarse roots by 25.2%, 23.3% and 14.4%, respectively. However, warming significantly increased carbon and nitrogen allocation proportions of shrub fine roots by 86.5% and 96.2%, respectively. While warming decreased the carbon and nitrogen allocation proportions of the aboveground parts of herbs by 19.5% and 18.9%, respectively, but significantly increased the carbon and nitrogen allocation proportions of the belowground parts of herbs by 15.6% and 24.8%, respectively. (3) Pearson correlation analysis and multiple linear regression analysis showed that the air temperature and soil microbial biomass were the main factors influencing the aboveground carbon and nitrogen allocation of shrubs, which could explain more than 72.0% of the variance. While the soil temperature, soil organic carbon and soil urease activity were the main factors influencing the belowground carbon and nitrogen allocation of shrubs, which could explain more than 92.0% of the variance. Whereas the soil organic carbon, soil invertase and urease activities were the main factors influencing the above- and belowground carbon and nitrogen allocation of herbs, which could explain more than 92.8% of the variance. (4) Soil nitrogen availability had no effect on carbon and nitrogen allocation of alpine shrubs and herbs. These findings indicated that as the climate warms in the future, the alpine shrub and herb plants in the S. angustata shrudlands will enhance the carbon and nitrogen allocation to belowground parts to better adapt to the rise in ambient temperature in these alpine shrublands on the eastern Qinghai-Tibet Plateau.

Abstract:In order to reveal the differences in the absorption and accumulation characteristics of metal elements in Azolla Lam., we determined and analyzed the contents of 12 metal elements in 21 strains from 8 species of Azolla. by ICP-MS. The differences and enrichment characteristics of metal elements in different species of Azolla. were compared. The characteristic metals of Azolla. were determined by principal component analysis, and the tested resources were classified by clustering method. The results showed that: (1) the variation coefficient of metal element contents in 8 species of Azolla was greater than 30%. The difference of Mo content between strains was the largest (127.73%), and the difference of Ca content between strains was the smallest (18.94%). (2) The enrichment ability of different kinds of Azolla to different metal elements in soil was different, and the enrichment coefficient was Mn > Mg > Mo > K > Cd > Ca > 1. (3) There were significant differences in the enrichment ability of different Azolla to metal element K, Mg, Mn, Zn and Mo among different species (P < 0.05). (4) The characteristic metal elements of Azolla are Cd, Hg, Ca, Mn, Cu, Zn, K and Cr. (5) The clustering results based on the contents of characteristic metal elements showed that when the genetic distance was 15, the 21 Azolla resources could be divided into 3 groups, which was basically consistent with the traditional classification. Among them, the strains ‘3006’ and ‘MH3-1’ had strong enrichment ability for heavy metals Cd, Cr and Hg, and were clustered into one category. The study suggests that there are interspecific differences in the enrichment of metal elements in Azolla, and this difference could be used as a reference for the classification of Azolla varieties.

Abstract:In order to explain the resource allocation characteristics of plant leaves and their adaptation strategies with soil factors, the study carried out in a pure plantation of Pinus tabuliformis and Pinus sylvestris and a mixed forest of Caragana korshinskii in Xinrong District, Datong City, Shanxi Province, on the northeastern edge of the Loess Plateau, using the sample method to collect branches in the four directions of east, west, north and south from the well-grown whorls in the middle of the canopy of the sample trees, and to select representative annual and perennial leaves at three locations on each branch: inside, middle and outside; nine sampling points were selected in each sample square using the “S” sampling method. The soil samples were collected by soil auger from 0 to 20 cm at each site; the functional characteristics, soil physical and chemical properties and the relationship between the two were determined and analysed under different silvicultural patterns of P. tabuliformis and P. sylvestris. The results showed that: (1) the differences in leaf functional traits between different afforestation modes of P. tabuliformis and P. sylvestris were concentrated between stoichiometry; as leaf age increased, P. tabuliformis and P. sylvestris both showed an increase in dry matter content and a decrease in N and P contents. (2) Soil total P and total N contents were the main explanatory factors for current year and perennial leaves of P. tabuliformis, respectively. Soil total P was significantly and positively correlated with current year leaf C∶N ratio, organic C and C∶P ratio, and negatively correlated with total N, leaf area and leaf dry matter content, while soil total N was positively correlated with perennial leaf total P content, and negatively correlated with leaf organic C, C∶P ratio and C∶N ratio. (3) The key soil factors for the functional traits of annual leaves of P. sylvestris were soil bulk and total P content, which were positively correlated with the ratio of leaf C, N and P, dry matter content and C content, and negatively correlated with N and P contents; the key soil factors for the functional traits of perennial leaves were soil bulk, water content and pH, which were positively correlated with leaf N and P contents, and negatively correlated with C content, dry matter content and specific leaf area, etc. (4) Leaf functional traits in pure stands of P. tabuliformis and P. sylvestris were more likely to be shifted towards higher levels of key soil factors, suggesting that the mixture with Caragana korshinskii can effectively differentiate the concentrated demand for key soil factors for leaf growth. However, the growth of the stands was weakened in the mixed afforestation mode, which was combined with the lack of resources in the study area and the high planting density of the stands, and the competition increased the survival pressure resulting in the restricted growth of the stands.

Abstract:The mixed evergreen and deciduous broad-leaved forest in karst is a non-zonal climax forest community in southwest China. This study used three structural parameters based on the relationship between adjacent trees to analyze the spatial structural characteristics of the overall, canopy, and understory and dominant species in a 25 hm² fixed monitoring plot of the mixed evergreen and deciduous broad-leaved forest, in order to reveal the spatial structural status of the forest and provide a scientific basis for karst vegetation restoration and reconstruction. The results showed that: (1) the overall distribution pattern of the plot community was slightly aggregated and close to random distribution, with highly mixed species and similar size differentiation among individuals. The upper wood layer showed random distribution, mixed intensity, and moderate subdominant, while the lower wood layer showed aggregated distribution, mixed intensity, and moderate partial dominance. (2) Most of the dominant species in the plots were in the state of mild aggregation distribution, mixed intensity, and moderate to inferior. (3) The ratio of tree size was significant negatively correlated with DBH and tree height, while the degree of mixing was significant positively correlated with DBH and tree height. With the growth and development of trees, the dominance of tree species gradually increased, and species diversity gradually increased.It was concluded that the spatial structural of the mixed evergreen and deciduous broad-leaved forest has not been completely stable, is in the middle and late succession, and has the potential to develop into a climax community.

Abstract:Caragana roborovskyi is a strong arid dwarf shrub, mainly distributed in desert steppe and steppe desert. This research is based on sampling-point map of distribution records of C. roborovskyi, generated from 130 records obtained from herbals and digital specimen databases, and used ensemble model to simulate the potential geographical distribution of C. roborovskyi during the LGM, Mid-Holocene, current and future climate scenarios (2030s), and used ArcGIS to calculate the suitable area and centroid migration trajectory to discuss the effects of climatic variation since the Last Glacial Maximum on the distribution of C. roborovskyi. The impact of climate change on the distribution of C. roborovskyi will provide a theoretical basis for the protection of C. roborovskyi under the background of climate change. The results showed that: (1) the effect of precipitation factor on the distribution of C. roborovskyi was higher than that of temperature factor and terrain factor; (2) In the current, the medium and high suitable regions of C. roborovskyi was 10.172×10⁵ km², and the centroids were located in Alxa Left Banner; (3) The centroid of LGM moved southeast to the centroid of Mid-Holocene, and then moved northeast to current centroid. C. roborovskyi could better adapt to the cold and dry environment of Last Glacial Maximum; (4) Under the future RCP2.6, RCP4.5 and RCP6.0 scenarios, the area of medium and high suitable regions significantly increased, but under the condition of RCP8.5, the area was decreased by 1.981×10⁵ km² compared with the current situation. It is speculated that the mild climate warming was beneficial to the survival and distribution of C. roborovskyi.

Abstract:A newly recorded species Meehania urticifolia (Miq.) Makino was found in Miyun District, Beijing. This species, and its corresponding genus Meehania Britton were both new records from Beijing. Its morphological characteristics and habitat were described. The voucher specimen was deposited in Zhejiang University Herbarium (HZU). Meehania urticifolia was first discovered in Japan in 1899 and was distributed in Northeast Asia. In China, it was only known Northeast China previously. Its discovery in Yunmeng Mountain of Beijing was obviously the westernmost distribution of this species in China. They may have come from Northeast Asia during the ice age.

Abstract:There are various types of membraneless organelles in cells, which play important roles in sensing environmental signals, regulating gene expression, RNA processing, etc.. Biomolecular phase separation has been proven to be the main way of forming membraneless organelles. This article introduces the concept and characteristics of biomolecular phase separation, summarizes research progress of phase separation in plants response to environmental signals, and categorizes the biological functions of phase separation in plants in order to analyze the mechanisms by which phase separation plays a role in plant growth and development and adaptation to adversity, thereby to understand the natures and functions of plant membraneless organelles.