Study on the Teaching Reform of Plant Physiology in the Context of Modern Education

The Plant Physiology is characterized by wide coverage,strong theories and practicality,and limited class hour.In view of these characteristics,this paper introduced the reform of teaching methods,including reform of teaching content,reform of teaching methods and means,reform of experimental teaching and examination methods.It is expected to achieve the objective of improving the teaching effect of Plant Physiology.

Comparative Analysis of Various Strains of Plant Growth Promoting Rhizobacteria on the Physiology of Garlic (Allium sativum)

Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhizobacteria (PGPR) on garlic (Allium sativum L.) growth and biochemical contents. Garlic cloves were inoculated with 3 kinds of PGPRs, Pseudomonas putida (KX574857), Pseudomonas stutzeri (Kx574858) and Bacillus cereus (ATCC14579) at 108 cells/mL prior to sowing. Under natural conditions, plants were grown in the net house. The PGPR significantly enhanced % germination, leaf and root growth and their biomass also increased the diameter of bulb and fresh and dry weight. The flavonoids, phenolics, chlorophyll, protein and sugar content were also significantly increased due to PGPR inoculation. The Pseudomonas stutzeri was found most effective for producing longer leaves with moderate sugar, high flavonoids (129%) and phenolics (263%) in bulb over control (Tap). The Pseudomonas putida exhibited a maximum increase in bulb diameter and bulb biomass with maximum phenolics and flavonoid contents.

The effect of dehydration on plant regeneration and some physiology characters in rice calli

The plant regeneration frequencies of ealli fromplant tissue and cell culture,especially that of thecalli from rice tissue culture and rice anther cul-ture,and that of the foreign-DNA-transfor-mation-derived rice calli is very low(usually 10-15%).It is therefor very important to improve theplant regeneration frequency of rice calli.A1-

Influencing in vitro clonal propagation of Chonemorpha fragrans(moon) Alston by culture media strength,plant growth regulators,carbon source and photo periodic incubation

Chonemorpha fragrans is an endangered medicinal woody climber,regarded among alternative plant sources of camptothecin.Camptothecin is a monoterpene indole anti-cancer alkaloid with annual trade value of over three billion U.S.dollars in the recent,and is used in the production of its analog drugs approved for the chemotherapy of cancer of varied types.Effects of plant growth regulators,culture media strength and photoperi-odic duration on the micropropagation ef ciency of C.fragrans from nodal segment explants were studied on Murashige and Skoog(MS)medium amended with Thidiazuron(TDZ),Benzylaminopurine(BAP)or Kinetin(Kin).Thidiazuron was more ef cient over BAP and Kin when half basal MS medium was used over full or quarter strength.Results of carbon source experiment showed sucrose as the most effective over glucose,fructose,and maltose in the clonal production.Studies on the photope-riodic incubation duration showed 12 h as the best light period and sub or supra-optimal resulted in the production of abnormal and albino micro shoots.Experimental results on the evaluation of physiological,biochemical parameters showed the role of pigment molecules and antioxidant systems in the production of albino micro shoots.

Ethanol Metabolism in Calluses of Several Selected Plant Species on Two Typical Plant-Growth-Regulator Balanced Media

For investigation on the characteristics of ethanol metabolism in tissues of different plant species, calluses from eight selected plant species were cultured on medium supplemented with ethanol in tightly sealed culture flasks. Changes of the ethanol level were detected by gas chromatography. During the culture period, the calluses of tobacco, potato and petunia were, able to catabolize exogenous ethanol, resulting in the prominent decline of the ethanol level in the medium. The calluses of melon and peanut were also able to catabolize thanol but with lower efficiency. The other three calluses of carrot, soybean and rice did not catabolize ethanol but instead produced small to large amount of ethanol, resulting in the increase of the ethanol level in the media. It was also found that changing the balance between auxin and cytokinin could influence only the ethanol metabolism efficiency but could not change the metabolism patterns on ethanol of the cultured calluses. It can be concluded that, ethanol metabolism pattern of calluses in cultures is an innate physiological characteristic of the respective plant species.

Low Doses of Ionized Radiation and Hypomagnetic Field Alter Redox Properties of Water and Physiological Characteristics of Seeds of the Highest Plants

The influence of a 40-fold attenuated geomagnetic field and its combined action with low doses of α- and γ-irradiation on the physiological characteristics of seeds of the highest plants and redox properties of water was investigated. It established the reduction of seed germination both under direct and indirect effects due to water action of attenuated geomagnetic field. A negative effect of hypomagnetic field on grown characteristics of seeds under indirect effect via water was decreased by the low doses of γ-irradiation, and was increased by low doses of α-irradiation, i.e. ionized radiation was the dominant factor in their combined action. It was revealed the increasing of the value of the oxidation-reduction potential of water under the influence of low-intensive α-ir-radiation (239Pu), γ-irradiation (137Cs) and also that the magnetic induction attenuated pointing to a natural decline. The increasing of the oxidation-reduction potential value testifies about “the regular decreasing of internal energy of water molecules” and the increasing of its oxidative properties, which, in our opinion, is caused the inhibition of the germination of seeds. It is supposed that namely water is the main component in the effects of studying factors on bio-objects, which acts due to the alterations of the properties and structural content of water.

Physiological and Biochemical Mechanisms of Salinity Tolerance in Carex morrowii Boott

Carex species are widely used in many parts of the world and contain a large number of ecologically diverse species.Among the Carex species,some of them are known to be glycophytes,while others are halophytes.Carex morrowii Boott(Cyperaceae)is resistant to trample through their root structure and has an essential ornamental value in the landscape with their leaves.However,no information was found about the level of salinity tolerance/sensitivity of the Carex morrowii among these species.In the present study,changes in trace element contents(Na,K,Ca,Cu,Mn,Mg,Ni,Fe,P,Zn,and N)and their transport from roots to leaves,osmotic regulation,alterations in chlorophyll and carotenoid contents,nitrogen assimilation(nitrate reductase activity;NRA)and total soluble protein content in both roots and leaves of Carex morrowii under different salinity concentrations(50 mM,100 mM,200 mM and 300 mM NaCl)were examined in detail.Our study provides the first detailed data concerning the responses of leaves and roots and the determination of the level of salinity tolerance/sensitivity of the Carex morrowii.The K+/Na+ratio was preserved up to 200 mM NaCl,and accordingly,the element uptake and transport ratios showed that they could control moderate NaCl levels.Ca homeostasis that is maintained even in 200 mM NaCl concentration can be effective in maintaining the structural integrity and selective permeability of the cell membranes,while 300 mM NaCl concentration caused decreased photosynthetic pigments,and deterioration in element content and compartmentation.Moreover,these data suggest that plant parts of Carex morrowii respond differently against varied levels of salinity stress.Although the decrease in NR activity at 200 mM and 300 mM NaCl concentrations in the leaves,NR activity was maintained in the roots.Consequently,Carex morrowii is moderately tolerant to salinity and the carotenoid content and osmotic regulation of Carex morrowii appears to be instrumental in its survival at different salinity levels.Especially the roots of Carex morrowii have a remarkable role in salinity tolerance.

Adaptive mechanisms of Ardisia crenata var.bicolor along an elevational gradient on Gaoligong Mountain,Southwest China

Plants overcome environmental stress by generating metabolic pathways.Thus,it is crucial to understand the physiological mechanisms of plant responses to changing environments.Ardisia crenata var.bicolor has an important ornamental and medicinal value.To reveal the impact of elevational gradient on the habitat soil and plant physiological attributes of this species,we collected root topsoil(0–20 cm)and subsoil(20–40 cm)samples and upper leaves at the initial blooming phase,in a survey of six elevations at 1,257 m,1,538 m,1,744 m,1,970 m,2,135 m,and 2,376 m,with 18 block plots,and 5sampling points at each site.Temperature decreases with an increase in elevation,and soil variables,and enzymatic activities fluctuated in both the topsoil and subsoil,with all of them increasing with elevation and decreasing with soil depth.Redundancy analysis was conducted to explore the correlation between the distribution of A.crenata var.bicolor along the elevational gradient and soil nutrients and enzyme activities,the soil properties were mainly affected by p H at low elevations,and governed by total phosphorus(TP)and available nitrogen(AN)at high elevations.The levels of chlorophyll,carbohydrates,and enzymatic activity except for anthocyanin in this species showed significant variation depending on physiological attributes evaluated at the different collection elevations.The decline in chlorophyll a and b may be associated with the adaptive response to avoid environmental stress,while its higher soluble sugar and protein contents play important roles in escaping adverse climatic conditions,and the increases in activities of antioxidant enzymes except peroxidase(POD)reflect this species’higher capacity for reactive oxygen scavenging(ROS)at high elevations.This study provides supporting evidence that elevation significantly affects the physiological attributes of A.crenata var.bicolor on Gaoligong Mountain,which is helpful for understanding plant adaptation strategies and the plasticity of plant physiological traits along the elevational gradients.

Effects of 17β-Estradiol on Growth, Primary Metabolism, Phenylpropanoid-Flavonoid Pathways and Pathogen Resistance in Arabidopsis thaliana

Mammalian sex hormones are spread in the environment from natural and anthropogenic sources. In the present study, the effect of estradiol on Arabidopsis thaliana growth primary metabolism, phenylpropanoid and flavonoid pathways and pathogen resistance were investigated. Treatments of Arabidopsis plants with 10 and 100 nM 17β-estradiol resulted in enhanced root growth and shoot biomass. In addition, treated plants had an increased rate of photosynthesis with a concomitant increase in carbohydrate and protein accumulation. Plants exposed to higher concentrations of 17β-estradiol (10 μM) had significantly lower root growth, biomass, photosynthesis rate, primary metabolite and phenylpropanoid and flavonoid contents indicating a toxic effect of estradiol. Treatments with increasing estradiol concentrations (10 nM, 100 nM and 10 μM) resulted in the downregulation of phenylpropanoid-flavonoid pathway genes (PAL1, PAL4, CHI and ANS) and subsequent decreased accumulation of phenolics, flavonoids and anthocyanins. Estradiol-treated plants were inoculated with Pseudomonas syringae pv. Tomato DC3000 and basal resistance was determined. Estradiol treatments rendered plants susceptible to the pathogen, thus compromising the plant defense mechanisms. These results indicate that at low concentrations, estradiol functions as a biostimulant of growth, yield and primary metabolism of Arabidopsis. However, estradiol functions as a potential transcriptional regulator of the phenylpropanoid pathway genes in Arabidopsis, having a negative effect on the phenylpropanoid and flavonoid biosynthetic pathways.

Effect of Lanthanum on Rice Growth and Phy siological Parameters with Split-Root Nutrient Solution Culture

Split-root solution culture was used to study the promoting effect of lanthanum on rice (Oryza sativa) growth and its physiological mechanisms. Results sho w that low concentration (0.05～1.5 mg·L -1) increases rice yield an d grain numbers. High concentration depresses grain formation (9～30 mg·L -1 ) and root elongation (1.5～30 mg·L -1). No significant influence on str aw dry weight was found over the whole concentration range except the 0.05 mg·L -1 treatment. With the increase of La concentration from 0.05 to 0.75 mg· L -1, catalase (CAT) activity in the first fully expandeing leaves and root s decreases. When La concentration is greater than 0.75 mg·L -1 or less than 9 mg·L -1, it significantly decreases superoxide dismutase activity ( SOD) in the leaves and roots. No significant effects were found on chlorophyll, protein and malondialdehyde (MDA) content. Possible mechanisms of La′s promotin g effect on rice growth and reduction effect of ·O- 2 were discussed.

Assessment of organic compost and biochar in promoting phytoremediation of crude-oil contaminated soil using Calendula officinalis in the Loess Plateau, China

The Loess Plateau,located in Gansu Province,is an important energy base in China because most of the oil and gas resources are distributed in Gansu Province.In the last 40 a,ecological environment in this region has been extremely destroyed due to the over-exploitation of crude-oil resources.Remediation of crude-oil contaminated soil in this area remains to be a challenging task.In this study,in order to elucidate the effects of organic compost and biochar on phytoremediation of crude-oil contaminated soil(20 g/kg)by Calendula officinalis,we designed five treatments,i.e.,natural attenuation(CK),planted C.officinalis only(P),planted C.officinalis with biochar amendment(PB),planted C.officinalis with organic compost amendment(PC),and planted C.officinalis with co-amendment of biochar and organic compost(PBC).After 152 d of cultivation,total petroleum hydrocarbons(TPH)removal rates of CK,P,PB,PC and PBC were 6.36%,50.08%,39.58%,73.10%and 59.87%,respectively.Shoot and root dry weights of C.officinalis significantly increased by 172.31%and 80.96%under PC and 311.61%and 145.43%under PBC,respectively as compared with P(P<0.05).Total chlorophyll contents in leaves of C.officinalis under P,PC and PBC significantly increased by 77.36%,125.50%and 79.80%,respectively(P<0.05)as compared with PB.Physical-chemical characteristics and enzymatic activity of soil in different treatments were also assessed.The highest total N,total P,available N,available P and SOM(soil organic matter)occurred in PC,followed by PBC(P<0.05).C.officinalis rhizospheric soil dehydrogenase(DHA)and polyphenol oxidase(PPO)activities in PB were lower than those of other treatments(P<0.05).The values of ACE(abundance-based coverage estimators)and Chao 1 indices for rhizospheric bacteria were the highest under PC followed by PBC,P,PB and CK(P<0.05).However,the Shannon index for bacteria was the highest under PC and PBC,followed by P,PB and CK(P<0.05).In terms of soil microbial community composition,Proteiniphilum,Immundisolibacteraceae and Solimonadaceae were relatively more abundant under PC and PBC.Relative abundances of Pseudallescheria,Ochroconis,Fusarium,Sarocladium,Podospora,Apodus,Pyrenochaetopsis and Schizothecium under PC and PBC were higher,while relative abundances of Gliomastix,Aspergillus and Alternaria were lower under PC and PBC.As per the nonmetric multidimensional scaling(NMDS)analysis,application of organic compost significantly promoted soil N and P contents,shoot length,root vitality,chlorophyll ratio,total chlorophyll,abundance and diversity of rhizospheric soil microbial community in C.officinalis.A high p H value and lower soil N and P contents induced by biochar,altered C.officinalis rhizospheric soil microbial community composition,which might have restrained its phytoremediation efficiency.The results suggest that organic compost-assisted C.officinalis phytoremediation for crude-oil contaminated soil was highly effective in the Loess Plateau,China.

Impact of Asarum Essential Oils on Physiological and Biochemical Indicators of Two Agricultural Pests

[Objective]The paper was to study the effects of asarum essential oils on physiological and biochemical indices of two agricultural pests. [Method]Asarum essential oils were extracted by different methods,and their effects on physiological and biochemical indices related to the structure of body wall（ chitin and phenoloxidase）,the physiological and biochemical indices acting on the nervous system（ Acetylcholinesterase）,and the physiological and biochemical indices acting on the digestive system（ protease,amylase and lipase） of Ostrinia furnacalis and Mythimna seperata were studied. [Result]Asarum essential oils had no effect no chitin content of body wall under the experimental concentration,and had no inhibitory effect but activated effect on polyphenol oxidase activity. Asarum essential oils could act on the nervous system of insect,and had strong inhibitory effect against acetylcholinesterase activity of O. furnacalis larvae,with inhibition rates of 24. 86%- 38. 79%. Asarum essential oils showed a significant activated effect on pepsin activity in midgut,but the activated amplitude became smaller with the prolongation of treatment time. Asarum essential oils showed a significant inhibitory effect on activities of amylase and lipase,indicating that it could play an insecticidal effect by inhibiting activity of amylase and lipase,and it could act on digestive system of insect. [Conclusion]The study laid the foundation for further development of asarum as botanical pesticide.

Plant E3 Ligases： Flexible Enzymes in a Sessile World

Since its discovery in the late 1970s, the ubiquitin proteasome pathway appears to be omnipresent in many research fields. Although originally discovered in animals, the pathway has a very central role in plants, which may be correlated to their sessile lifestyle. E3 ligases function as flexible and highly diverse key regulators within the path- way by targeting substrate proteins for ubiquitylation, and often proteolytic degradation via the 26S proteasome. This review provides a concise overview on the most common classes of E3 ligases so far described in plants, and emphasizes recent findings regarding these interesting and flexible enzymes and their diverse functions in plant biology.

Hydrogen sulfide, a signaling molecule in plant stress responses

Gaseous molecules, such as hydrogen sulfide(H_2S)and nitric oxide(NO), are crucial players in cellular and(patho)physiological processes in biological systems. The biological functions of these gaseous molecules, which were first discovered and identified as gasotransmitters in animals, have received unprecedented attention from plant scientists in recent decades. Researchers have arrived at the consensus that H_2S is synthesized endogenously and serves as a signaling molecule throughout the plant life cycle.However, the mechanisms of H_2S action in redox biology is still largely unexplored. This review highlights what we currently know about the characteristics and biosynthesis of H_2S in plants. Additionally,we summarize the role of H_2S in plant resistance to abiotic stress. Moreover, we propose and discuss possible redox-dependent mechanisms by which H_2S regulates plant physiology.

Ion Channels in Plant Bioenergetic Organelles, Chloroplasts and Mitochondria： From Molecular Identification to Function

Recent technical advances in electrophysiological measurements, organelle-targeted fluorescence imaging, and organelle proteomics have pushed the research of ion transport a step forward in the case of the plant bioenergetic organelles, chloroplasts and mitochondria, leading to the molecular identification and functional characterization of several ion transport systems in recent years. Here we focus on channels that mediate relatively high-rate ion and water flux and summarize the current knowledge in this field, focusing on targeting mechanisms, proteomics, electrophysiology, and physiological function. In addition, since chloroplasts evolved from a cyanobacterial ancestor, we give an overview of the information available about cyanobacterial ion channels and discuss the evolutionary origin of chloroplast channels. The recent molecular identification of some of these ion channels allowed their physiological functions to be studied using genetically modified Arabidopsis plants and cyanobacteria. The view is emerging that alteration of chloroplast and mitochondrial ion homeostasis leads to organelle dysfunction, which in turn significantly affects the energy metabolism of the whole organism. Clear-cut identification of genes encoding for chan- nels in these organelles, however, remains a major challenge in this rapidly developing field. Multiple stra- tegies including bioinformatics, cell biology, electrophysiology, use of organelle-targeted ion-sensitive probes, genetics, and identification of signals eliciting specific ion fluxes across organelle membranes should provide a better understanding of the physiological role of organellar channels and their contribution to signaling pathways in plants in the future.

Single-Cell Transcriptome Analysis in Plants:Advances and Challenges

The rapid and enthusiastic adoption of single-cell RNA sequencing(scRNA-seq)has demonstrated that this technology is far more than just another way to perform transcriptome analysis.It is not an exaggeration to say that the advent of scRNA-seq is revolutionizing the details of whole-transcriptome snapshots from a tissue to a cell.With this disruptive technology,it is now possible to mine heterogeneity between tissue types and within cells like never before.This enables more rapid identification of rare and novel cell types,simultaneous characterization of multiple different cell types and states,more accurate and integrated understanding of their roles in life processes,and more.However,we are only at the beginning of unlocking the full potential of scRNA-seq applications.This is particularly true for plant sciences,where single-cell transcriptome profiling is in its early stage and has many exciting challenges to overcome.In this review,we compare and evaluate recent pioneering studies using the A rabidopsis root model,which has established new paradigms for scRNA-seq studies in plants.We also explore several new and promising single-cell analysis tools that are available to those wishing to study plant development and physiology at unprecedented resolution and scale.In addition,we propose some future directions on the use of scRNA-seq technology to tackle some of the critical challenges in plant research and breeding.

Reducing residues of tetracycline and its resistance genes in soil-maize system and improving plant growth:Selecting the best remediation substance

Tetracycline(TC)and tetracycline resistance genes(TRGs)in plant edible tissues pose a potential risk to the environment and then to human health.This study used a pot experiment to investigate the effects of different remediation substances(worm castings,fungal chaff,microbial inoculum,and biochar)on the physiological characteristics of maize and the residues of TC and TRGs in the soil-maize system under TC stress.The results showed that TC significantly inhibited growth,disrupted the antioxidant defense system balance,and increased proline and malondialdehyde contents of maize plants.Tetracycline residue contents were significantly higher in root than in shoot,and followed the order root>stem-leaf>grain,which was consistent with the distribution of bioconcentration factors in the different organs of maize plants.The TC residue content in the soil under different treatments was 0.013–1.341 mg kg-1.The relative abundances of different antibiotic resistance genes in the soil-maize system varied greatly,and in maize plants followed the order intI1>tetW>tetG>tet B>tetM>tetX>tetO.In the soil,tetX had the highest relative abundance,followed by tetG and tetW.A redundancy analysis(RDA)showed that TC was positively correlated with TRGs.The addition of different remediation substances alleviated the toxicity of TC on maize physiological characteristics and reduced the TC and TRG residues in the soil-maize system,with biochar being the best remediation substance.These results provide new insights into the effect of biochar on the migration of TC and TRGs from soil to plants.

Arabidopsis Thylakoid Formation 1 Is a Critical Regulator for Dynamics of PSII-LHCII Complexes in Leaf Senescence and Excess Light

In higher plants, photosystem II （PSII） is a large pigment-protein supramolecular complex composed of the PSII core complex and the plant-specific peripheral light-harvesting complexes （LHCil）. PSli-LHCII complexes are highly dynamic in their quantity and macro-organization to various environmental conditions. In this study, we reported a critical factor, the Arabidopsis Thylakoid Formation 1 （THF1） protein, which controls PSII-LHCII dynamics during dark- induced senescence and light acclimation. Loss-of-function mutations in THF1 lead to a stay-green phenotype in path- ogen-infected and senescent leaves. Both LHCII and PSll core subunits are retained in dark-induced senescent leaves of thfl, indicative of the presence of PSII-LHCII complexes. Blue native （BN）-polyacrylamide gel electrophoresis （PAGE） and immunoblot analysis showed that, in dark- and high-light-treated thfl leaves, a type of PSII-LHCII megacomplex is selec- tively retained while the stability of PSII-LHCII supercomplexes significantly decreased, suggesting a dual role of THF1 in dynamics of PSII-LHCII complexes. We showed further that THF1 interacts with Lhcb proteins in a pH-dependent manner and that the stay-green phenotype of thfl relies on the presence of LHCII complexes. Taken together, the data suggest that THF1 is required for dynamics of PSII-LHCII supramolecular organization in higher plants.

The Blue Light-Dependent Phosphorylation of the CCE Domain Determines the Photosensitivity of Arabidopsis CRY2

Arabidopsis cryptochrome 2 （CRY2） is a blue light receptor that mediates light inhibition of hypocotyl elongation and long-day promotion of floral initiation, CRY2 is known to undergo blue light-dependent phosphorylation, which is believed to serve regulatory roles in the function of CRY2. We report here on a biochemical and genetics study of CRY2 phosphorylation. Using mass spectrometry analysis, we identified three serine residues in the CCE domain of CRY2 （S588, S599, and S605） that undergo blue light-dependent phosphorylation in Arabidopsis seedlings. A study of serine-substitution mutations in the CCE domain of CRY2 demonstrates that CRY2 contains two types of phosphorylation in the CCE domain, one in the serine cluster that causes electrophoretic mobility upshift and the other outside the serine cluster that does not seem to cause mobility upshift. We showed that mutations in the serine residues within and outside the serine cluster diminished blue light-dependent CRY2 phosphorylation, degradation, and physiological activities. These results support the hypothesis that blue light-dependent phosphorylation of the CCE domain determines the photosensitivity of Arabidopsis CRY2.