Light energy is an important factor affecting plant growth. The hypothesis of "light-cold and heat property" holds that the original plants of traditional Chinese medicines(TCM) with cold property can obtain more energy to maintain growth in high light intensity environment, whereas the original plants of TCM with heat property prefer weak light environment. The current experiment investigated the effects of different light intensities on primary metabolites levels, energy levels, cell apoptosis, and leaves ultrastructure of Viola yedoensis, the original plants of TCM Violae Herba with cold property. There were five treatment groups of V. yedoensis, which was planted under Li1(8 500 lx),Li2(7 250 lx),Li3(6 000 lx),Li4(4 750 lx),Li5(3 500 lx)LEDs light intensity conditions, respectively. After harvest, primary metabolites levels, contents of ATP, ADP, AMP, activities of ATP synthesis and hydrolysis related enzyme, as well as cell apoptosis activation degree were measured, and transmission electron microscopy technique was used to observe leaves ultrastructure. The results showed that the total sugar, total protein, contents of ATP, ADP and AMP, activities of NADH dehydrogenase, cytochrome C reductase, ATP synthase and ATP hydrolase were positively correlated with light intensities(P<0.05). The crude fat content, activities of SDH and CCO enzyme showed a trend of increasing first and then decreasing, the highest value were found in Li2 group and Li3 group respectively(P<0.05). The vitality of caspase-3 and caspase-9 was negatively correlated with light intensities(P<0.05). The structure of chloroplast and mitochondria were normal and intact in Li1-Li3 groups, and the damage degree of Li4 and Li5 groups increased with the decrease of light intensities. The analysis of results indicated that the structure of chloroplast and mitochondria of V. yedoensis is normal under the light intensity of 6 000-8 500 lx, which can obtain more energy to maintain its growth and metabolism. When the light intensity is lower than 4 750 lx, the chloroplast morphology and mitochondrial membrane are damaged, affecting the metabolism of material and energy. There was no significant difference in energy charge of V. yedoensis in the light intensity range of 3 500～8 500 lx. The effect of light intensity on energy metabolism of V. yedoensis accords with the hypothesis of "light-cold and heat property".
Chloroplasts ; Energy Metabolism ; Medicine, Chinese Traditional ; Plant Leaves ; Viola

Light is the main source for plants to obtain energy.Asarum forbesii is a typical shade medicinal plant, which generally grows in the shady and wet place under the bushes or beside the ditches.It can grow and develop without too much light intensity.This experiment explores the effects of shading on the growth, physiological characteristics and energy metabolism of A.forbesii, which can provide reference and guidance for its artificial planting.In this experiment, A.forbesii was planted under 80%, 60%, 40%, 20% and no shade.During the vigorous growth period, the photosynthetic physiological characteristics such as fluorescence parameters, photosynthetic parameters, photosynthetic pigment content and ultrastructure, as well as the content of mitochondrial electron transport chain(ETC) synthase and nutrients were measured.The results showed that the photosynthetic pigment content, chlorophyll fluorescence parameters and net photosynthesis rate(P_n) decreased with the decrease of shading.Under 20%-40% shading treatment, the plants had damaged ultrastructure, expanded and disintegrated chloroplast, disordered stroma lamella and grana lamella, and increased osmiophi-lic granules and starch granules.The activities of nicotinamide adenine dinucleotide dehydrogenase(NADH), succinate dehydrogenase(SDH), cytochrome C oxidoreductase(CCO) and adenosine triphosphate(ATP) synthasewere positively related to light intensity.With the reduction of shading, the content of total sugar and protein in nutrients increased first and then decreased, and the content was the highest under 60% shade.In conclusion, under 60%-80% shading treatment, the chloroplast and mitochondria had more complete structure, faster energy metabolism, higher light energy-conversion efficiency, better absorption and utilization of light energy and more nutrient synthesis, which was more suitable for the growth and development of A.forbesii.
Asarum ; Chlorophyll/metabolism* ; Chloroplasts ; Energy Metabolism ; Photosynthesis/physiology* ; Plant Leaves/metabolism*

The paper adopted the JEM-100CX II transmission electron microscope to observe chloroplast ultrastructure of five kinds of dandelion (Taraxacum) leaves in northeast, and the LI-6400 portable photosynthesis system was used to compare the chlorophyll fluorescence and the photosynthesis characteristics of five kinds of dandelions in Northeast China. Chloroplast ultrastructure showed: in the five kinds of dandelion, larger chloroplast, grana with more layers, regular thylakoid, without starch grains and so on, these chloroplasts characteristics decided to bigger photosynthetic rate. The five kinds of dandelion P(n) exhibited a "double peak" diurnal curve: stomatal limitation is the main adjustment factors for the midday depression phenomenon. The P(n),G(s),C(i) content of T. mongolicum are the highest, and T. asiaticum are the lowest among them. The relation between P(n) and G(s),C(i) is direct ratio, P(n) and T(r) is in an inverse proportion among the five kinds of dandelion. In addition, P(n) is positively correlated with Chla, Chlb, and the relationship with Chlb is bigger. The paper demonstrates the Mongolian dandelion photosynthetic efficiency is the highest, it is an higher photosynthetic efficiency dandelion,it provide theoretical basis for assessment and use of the resource of dandelion.
China ; Chlorophyll ; analysis ; Chloroplasts ; ultrastructure ; Photosynthesis ; Plant Leaves ; metabolism ; ultrastructure ; Taraxacum ; metabolism ; ultrastructure

GLKs (GOLDEN 2-LIKEs) are a group of plant-specific transcription factors regulating the chloroplast biogenesis, differentiation and function maintains by triggering the expression of the photosynthesis-associated nuclear genes (PhANGs). The GLKs also play important roles in nutrient's accumulation in fruits, leaf senescence, immunity and abiotic stress response. The expression of GLK genes were affected by multiple hormones or environmental factors. Therefore, GLKs were considered as the key nodes of regulatory network in plant cells, and potential candidates to improve the photosynthetic capacity of crops. Since numerous researches of GLKs have been reported in plants, the biological function, molecular mechanism of GLKs genes and its applications in breeding were summarized and a GLK-mediated signaling network model was developed. This review may facilitate future research and application of GLKs.
Chloroplasts/genetics* ; Gene Expression Regulation, Plant ; Photosynthesis/genetics* ; Plant Breeding ; Transcription Factors/metabolism*

OBJECTIVETo reveal the effects of UV-B radiation on the growth of medical plant Mentha piperita, simulate an enhanced UV-B radiation and evaluate intensity of radiation on the photosynthesis of M. piperita.

METHODThree different levels of UV-B radiation were set in the experiment which included: natural light control (0 W x m(-2)), light UV-B radiation stress (0.15 W x m(-2)) and heavy UV-B radiation stress (0.35 W x m(-2)). The chloroplast ultrastructure, photosynthesis indexes and chlorophyll fluorescence parameters of the M. piperita were observed under the three treatments.

RESULTAlthough the chloroplast ultrastructure was destroyed to some degree under the light UV-B radiation stress, F(v)/(F)m, F(v)/F(o), qP, phiPS II and ETR could resume to the comparative level of natural light control. At the same time, qN increased firstly and decreased thereafter. But under the high strength UV-B radiation stress, the photosynthetic structures were badly destroyed, which could not recover through protecting mechanism by itself.

CONCLUSIONIt was showed that M. piperita was able to protect photosynthetic structures by increasing respiration and dissipation when photosynthetic capacity reduced under light UV-B radiation stress. It is demonstrated that M. piperita has high adaptation to light UV-B radiation stress, which is kind of promising medical plant for area with higher UV-B radiation.

Chlorophyll ; metabolism ; Chloroplasts ; metabolism ; radiation effects ; ultrastructure ; Mentha piperita ; metabolism ; radiation effects ; ultrastructure ; Photosynthesis ; radiation effects ; Ultraviolet Rays

Thermostable alpha-amylase from Pyrococcus furious is an important industrial enzyme in brewing and alcohol production. Eexpression of the thermostable a-amylase in plants can reduce greatly costs in the production of alcohol using crop plants. A chloroplast expression vector, p64A, containing the thermostable alpha-amylase gene from Pyrococcus furious, was constructed with clpP-trnL-petB-chlL-rp123-rpl2 as Chlamydomonas reinhardtii plastid homologous recombinant fragments and spetinomycin-resistant aadA gene as select marker. The plasmid p64A was transferred into the chloroplast genome of C. reinhardtii by the biolistic method. Nine independently transformed lines were obtained by 100 mg/L spectinomycin selection. PCR amplification, Southern blot analysis of the transgene and cultivation in the dark all showed that the a-amylase gene had been integrated into chloroplast genome of C. reinhardtii. The activity of amylase expressed in the chloroplast of C. reinhardtii was detected by amylase activity assay and found to be as high as 77.5 u/g fresh weight of cells. These experimental results demonstrated the possibility of using transgenic chloroplasts of plant as bioreactors for production of industrial enzymes.
Chlamydomonas reinhardtii ; genetics ; Chloroplasts ; genetics ; Enzyme Stability ; Plasmids ; Polymerase Chain Reaction ; Pyrococcus furiosus ; enzymology ; alpha-Amylases ; chemistry ; genetics ; metabolism

Chloroplast-based expression system is promising for the hyper-expression of plant-derived recombinant therapeutic proteins and vaccines. To verify the feasibility of obtaining high-level expression of the SARS subunit vaccine and to provide a suitable plant-derived vaccine production platform against the severe acute respiratory syndrome coronavirus (SARS-CoV), a 193-amino acid fragment of SARS CoV spike protein receptor-binding domain (RBD), fused with the peptide vector cholera toxin B subunit (CTB), was expressed in tobacco chloroplasts. Codon-optimized CTB-RBD sequence was integrated into the chloroplast genome and homoplasmy was obtained, as confirmed by PCR and Southern blot analysis. Western blot showed expression of the recombinant fusion protein mostly in soluble monomeric form. Quantification of the recombinant fusion protein CTB-RBD was conducted by ELISA analysis from the transplastomic leaves at different developmental stages, attachment positions and time points in a day and the different expression levels of the CTB-RBD were observed with the highest expression of 10.2% total soluble protein obtained from mature transplastomic leaves. Taken together, our results demonstrate the feasibility of highly expressing SARS subunit vaccine RBD, indicating its potential in subsequent development of a plant-derived recombinant subunit vaccine and reagents production for antibody detection in SARS serological tests.
Chloroplasts ; metabolism ; Cholera Toxin ; Protein Interaction Domains and Motifs ; Recombinant Fusion Proteins ; biosynthesis ; SARS Virus ; Spike Glycoprotein, Coronavirus ; biosynthesis ; Tobacco ; metabolism ; Vaccines, Subunit ; biosynthesis

The heat shock protein ClpB is a member of the Clp family and functions as molecular chaperones. ClpB is related to the acquired thermotolerance in organisms. A cDNA of 3144 bp was screened out of a tomato cDNA library. The polypeptide deduced from the longest ORF contains 980 amino acid residues, and was classified into HSP100/ClpB family based on the result of molecular phylogenesis analysis. Thus it was named as LeHSP110/ClpB according to its calculated molecular weight. LeHSP110/ClpB was characteristic of heat-inducibility but no constitutive expression, and was demonstrated to locate in chloroplastic stroma. An antisense cDNA fragment of LeHsp110/ClpB under the control of CaMV 35S promoter was introduced into tomato by Agrobacterium tumefactions-mediated method. At high temperature, the mRNA levels of LeHsp110/ClpB in antisense transgenic plants were lower than those in control plants. The PS II of transgenic plants is more sensitive to high temperature than that of control plants according to data of Fv/Fm. These results clearly showed that HSP110/ClpB plays an important role in thermotolerance of high plants.
Adaptation, Physiological ; genetics ; Chloroplasts ; metabolism ; Cloning, Molecular ; Genes, Plant ; genetics ; HSP110 Heat-Shock Proteins ; genetics ; metabolism ; Hot Temperature ; Lycopersicon esculentum ; genetics ; physiology ; Photosystem II Protein Complex ; metabolism ; Plant Proteins ; genetics ; metabolism ; Plants, Genetically Modified ; genetics ; physiology

Rice leaf color mutants play a great role in research about the formation and development of chloroplasts and the genetic mechanism of the chlorophyll (Chl) metabolism pathway. pgl3 is a rice leaf color mutant derived from Xiushui11 (Oryza sativa L. spp. japonica), treated with ethyl methane sulfonate (EMS). The mutant exhibited a pale-green leaf (pgl) phenotype throughout the whole development as well as reduced grain quality. Map-based cloning of PGL3 revealed that it encodes the chloroplast signal recognition particle 43 kDa protein (cpSRP43). PGL3 affected the Chl synthesis by regulating the expression levels of the Chl synthesis-associated genes. Considerable reactive oxygen species were accumulated in the leaves of pgl3, and the transcription levels of its scavenging genes were down-regulated, indicating that pgl3 can accelerate senescence. In addition, high temperatures could inhibit the plant's growth and facilitate the process of senescence in pgl3.
Chlorophyll/metabolism* ; Chloroplasts/metabolism* ; Cloning, Molecular ; Gene Expression Regulation, Plant ; Genes, Plant ; Hot Temperature ; Mutation ; Oryza/physiology* ; Phenotype ; Photosynthesis ; Plant Leaves/metabolism* ; Plant Proteins/genetics* ; Reactive Oxygen Species/metabolism*

OBJECTIVETo study the mutagenic effect of gamma-rays on Coix lacryma-jobi var. ma-yuen.

METHODPhysiological and mutagenic effects of gamma-rays on C. lacryma-jobi var. ma-yuen dormant seeds were studied. The germination percentage, seeding survival, seeding height and root length of M1 plants and the frequency of chlorophyll mutation in M2 generation were selected as criteria.

RESULTThe gamma-rays showed obvious inhibitory action to the seedling growth, and a strong ability in inducing the chlorophyll mutation.

CONCLUSIONThe gamma-rays is one kind of C. lacryma-jobi var. ma-yuen effective mutagen. The appropriate dose of gamma-rays is 450 Gy for C. lacryma-jobi var. ma-yuen dormant seeds.

Chlorophyll ; metabolism ; Chloroplasts ; genetics ; metabolism ; radiation effects ; Cobalt Radioisotopes ; Coix ; genetics ; growth & development ; radiation effects ; Gamma Rays ; Germination ; genetics ; physiology ; radiation effects ; Inclusion Bodies ; Mutagenesis ; radiation effects ; Mutation ; radiation effects ; Plant Roots ; genetics ; growth & development ; radiation effects ; Radiation Dosage ; Seedlings ; genetics ; growth & development ; radiation effects ; Seeds ; genetics ; growth & development ; radiation effects