Vegetation reconstruction and restoration in the newly formed water-level-fluctuation zone (WLFZ) of the Three Gorges Reservoir Area is critically significance in ecological safety in the area and restoration of the anthropogenic-impacted ecosystem of the Yangtze River region.The natural zone and its riparian vegetation are among the most important components of the river watershed ecosystem and play a crucial role in ecological service and sustainable development for the local economy. Control of the water level in regulated rivers has led to a destroyed habitat for riparian vegetation, and the ecosystem is largely degraded, with little or no vegetation.The Three Gorges project is unavoidably destroying the riparian vegetation in the natural WLFZ and has led to the creation of a newly regulated WLFZ without vegetation. Results of extensive field surveys have revealed that exploitation of land resources in the area for the development of the local economy will be further deleterious to the environment and will have a great negative impact on the safety of the dam. Reconstruction and restoration of riparian vegetation along the newly formed WLFZ is urgently needed to gradually recover the ecological function and ecoservice in the up-stream Yangtze River.

Gravitropism of plant roots is one of the important factors determining the spatial pattern of root growth and thus may have a great effect on nutrient uptake. An understanding of the molecular mechanisms of root gravitropic response and subsequent root growth changes related to nutrient uptake would facilitate the genetic improvement of nutrient efficiency in plants. This review summarizes the molecular mechanisms of root gravitropic responses in terms of root gravity sensing, signal transduction and auxin asymmetrical distribution. It discusses the physiological basis of root gravitropic responses to nutrient stresses, especially phosphorus deficiency, and its relation to uptake of nutrients, especially phosphorus. Included are problems and perspectives for future research.

The metabolome refers to all the low-molecular-weight metabolites present in an organism or cell in a particular physiological period. The term plant metabolomics is used for defining the technology of high-throughput, nonbiased analyses of the metabolome of plant extracts. Research into plant metabolomics has advanced greatly during recent years. This review introduces the definition, history and research approaches of plant metabolomics and gives several typical examples to elucidate the application of plant metabolomics.

The cotyledons of Sacred Lotus (Nelumbo nucifeva) accumulate abundant storage reserves, including storage proteins in protein bodies, starch and DNA in amyloplasts, during seed development. Hydrolysis of these reserves provides sources for seed germination and seedling growth. Histochemical analysis revealed the entire process of reserve degradation in Sacred Lotus cotyledons, which occurs from seed germination to the stage of 4-noded vegetal body over about 45 days. Throughout this period, storage reserves are continuously involved in dynamic hydrolysis and transport activities. Protein bodies degrade before starch and aDNA hydrolysis, which mainly occurs at the trefoil stage. Amyloplasts may fuse into a large starch mass and hydrolyze gradually. In comparison with the trefoil stage, amyloplasts contain few DNA after 65 days of germination. In addition, diverse structural changes, related to transporta-tion of substances among cotyledon cells, occur in cell walls. Quantities of polysaccharide vesicles are transported in bulk through vascular bundles.

In vitro ear culture was used to determine the effect of concentrations of glutamine on grain weight and content of starch, protein and protein components in 2 wheat varieties,Yangmai 9 and Xuzhou 26, differing in grain protein content. Grain weight and starch and protein content increased with increasing glutamine concentration, and peaked at 6 g.L-1. The amino acid and protein content increased, while starch content decreased with increased glutamine.Consistent with increased total protein content, albumin and globulin content increased with increased glutamine. Grain gliadin and glutenin content increased with increasing glutamine, from 2-6 g.L-1, and leveled off after 6 g.L-1.

The effect of melatonin on the activity of arginine decarboxylase and cell viability was examined in tobacco suspension cells during cold stress. Melatonin could increase the activity of arginine decarboxylase and decrease the rate of cell death. Melatonin could enhance the resistance to chilling injury by regulating the synthesis of polyamine in plant cells.

Simulation tests of spring frost in strawberry (Fragaria ananassa) leaves and receptacles involved use of an artificial climate chamber. Leaves could tolerate intercellular freezing to some extent. At a tissue temperature of -6.4 ℃, leaves could survive 90-min freezing, but receptacles were not able to tolerate intercellular freezing. Receptacles resisted frost injury by maintaining a state of supercooling to avoid freezing. The proportion of receptacles injured was inversely related to decreased receptacle temperature, reaching 50% at -5.4 ℃. Full-blossom flowers and those with heavier fresh weight were susceptible to frost injury even at higher temperatures.

Pteris ensiformis is a perennial evergreen herbage with high ornamental and medicinal value. However, its resources have not been explored and utilized because of lack of understanding of its propagation. We successfully cultivated the spores of P. ensiformis in mixed soil and observed spore germination and gametophytic development by microscopy. The spores are brown, monolete, and bean-shaped in the equatorial view and triangular in the polar view. They germinate about 1 week after sowing. The germination is of the Vittaria type and the gametophyte development of the Ceratopteris type. The prothallial plate is formed about 3 weeks after sowing. The young prothalli are asymmetric and the mature are cordate and naked. The sex organs appear about 5 weeks after sowing. The antheridia consist of 3 cells. The archegonial neck usually consists of 4 rows and 4 columns of cells at maturity. Young embryos can be observed from the prothalli 1 month after sowing. This study reveals not only the technique of propagation of P.ensiformis with spores for horticulture but also the proper conditions for molecular biology,genetics and systematics study.

To confirm the most appropriate pharmaceutical source and harvest time and provide a scientific basis for exploiting Rumex gmelini, we used HPLC to examine the dynamic distribution of 7 components (resveratrol, polydatin, chrysophanol, chrysophaein, emodin, physcion and musizin) in organs, tissues and development stages of 1- or 2-year-old Rumex gmelini. The kind and content of active components varied in roots as compared with other plant parts, with roots being the most appropriate pharmaceutical source. Musizin was not found in 1-year-old plants. All 7 active components were found in roots of 2-year-old plants, and the content was higher during August and September, so this period is the most appropriate harvest time for R. gmelini.

Alliinase (EC.4.4.1.4) of fresh garlic (Allium sativum) was purified 14-fold by gel filtration on a SephadexG-200 system. SDS-PAGE revealed a molecular weight of 53 kD, with Km and Vmax values of 0.693 mmol.L-1 and 0.353 mol.L-1, respectively. The optimal temperature for activity was 30 ℃, with stable activity below 50 ℃. The activity was inhibited by Zn2+ stimulated by 0.1 mol Mn2+.

Camptothecin (CPT) content in organs of Camptotheca acuminata and young shoots from different areas of China was determined by HPLC. CPT content in leaves, seeds and young shoots was higher than that in xylem, lowest in piths and highest in young shoots from Sichuan province. CPT content in young biennial shoots was higher than that in annual shoots and that in caulody was higher than that in subbranches.

The growth and nicotine biosynthesis of hairy roots of Nicotiana tabacum in suspension culture are influenced by various factors such as basal medium, hormone content and the pH value. The maximal production of nicotine at 0.241 mg.mL－1 was obtained when one tip of hairy root was cultured in 40 mL liquid 1/2 Murashige Skoog medium supplemented with 1.0 mg.L－1 indolacetic acid at 26-28 ℃ under natural scattered light. This result suggests the potential application of a hairy root suspension culture system for the production of the second metabolic substance of Nicotiana tabacum.

Fluorescent-based real-time PCR is widely used for quantification of nucleic acids. It is becoming one of the most important techniques for molecular biology and biotechnology.Real-time PCR assay is easy to perform, capable of high throughput, and can combine high sensitivity with reliable specificity. The technique is evolving rapidly with the knowledge of new enzymes, chemistry and instrumentation. The principle of real-time PCR and its application in quantifying plant nucleic acids is reviewed.

Leaf-shape is a significant feature for plant recognition. Establishing computer recognition system is an essential topic for identifying plants. Image processing, feature abstraction and classification of plant leaf shape with computer recognition system were discussed in this paper. The system has been developed with Microsoft Visual Basic.Net under Windows 2000/XP system. It can accomplish leaf image input, transform, smoothness, segmentation and finding leaf margin, etc. The performance of the system to recognize leaf shape has been demonstrated with 93.8% precision rate through testing 337 samples which belong to 14 species of plants. This work is very essential for further studies.

We review and summarize the progress of studies of LEAFY genes. Sequence comparative analysis of the orthologs of genes isolated from a wide variety of plant species showed high similarity in coding sequence at the nucleotide and amino acid levels but different copy numbers, especially in diploid angiosperms. Orthologous genes, however, have variant expression patterns in different plants. Phylogenetic analysis of the predicted protein sequences of the orthologs supported the currently accepted theory of phylogenetic partnerships of plant species. The information summarized here is helpful not only for better understanding the mechanisms of plant flowering but also for further promoting studies of the evolution of flowering plants.

With the rapid industry development and population expansion since the beginning of the 20th century, the concentrations of heavy metals in agricultural soils have become increasingly high in China. Heavy metal pollution in paddy soil not only results in retardation of rice growth and development and subsequent yield losses but also is readily absorbed and accumulated by rice plants. By entering the food chain, it could threaten human health and damage the food safety in China. This paper reviews research advances into absorption, translocation and distribution of heavy metal in rice crops and its mechanisms and offers suggestions for future research.

This review describes recent progress in genetic engineering to produce edible vegetable oils with predefined modified compositions. The genetic modification of plant oil for improving nutritional properties has made great strides over the past decade. Because plant lipid biosynthetic pathways are being rapidly elucidated, many new plant oils containing novel fatty acids with creditable health benefits can be enhanced in transgenic oilseed crops.

We review hypotheses on the limitation of tree height growth. The tree maturation hypothesis considers that the change in genetic expression as tissue ages and the number of cell divisions increases may slow growth. The nutrient limitation hypothesis suggests that decreasing nutrient supply from the soil with tree growth leads to a shift in carbon allocation to root production or reduced physiological capacity and, consequently, suppression of height growth. The tissue-respiration hypothesis considers that the fraction of assimilates available for wood production declines as wood biomass and respiration of living cells increases. The hydraulic limitation hypothesis considers that the total hydraulic resistance between the soil and leaves, which induces the leaf stomata closing earlier during the day to avoid cavitation in xylem and lowered time-integrated photosynthesis, increases as trees grow taller. However, several compensation mechanisms, including changes in leaf characteristics with tree height, decreased leaf/sapwood area, increased xylem permeability, and water storage in the stems, may also contribute to maintaining plant water balance under height growth. Although it has strongly been debated, the hydraulic limitation hypothesis has gained much support from empirical results.