Plant architecture or plant type is one of the key target traits for crop improvement, and the stem traits play leading roles in the formation of plant architecture. Previous studies of plant developmental molecular biology showed that the formation and development of stem traits are controlled by many key genes. This review summarizes the approaches to the molecular mechanism of stem development, including its initiation, shaping and branching, to provide a theoretical basis for the modification of plant architecture.

This article reviews the progress in biotechnology research and development of Amorphophallus Blume (konjac ) in the past 20 years. At present, tissue culture is a major part of the konjac biotechnology. In vitro plant regeneration occurs mainly via organogenesis, which consists of bud or cormlet formation; the latter is the focal point of current research. Useful results have been obtained in the selection of useful somaclonal variation and germplasm conservation by konjac tissue culture. In addition, rapid progress has been made in genetic transformation, with the aim of improving disease resistance and quality. Disease- and herbicide-resistant genes have been successfully transformed into konjac plants. Meanwhile, problems remaining for biotechnology research and development are discussed, and the solutions pertinent to the problems are also put forward.

The phytolith evidence of rice together with AMS 14C dating of charcoal and charred seed from Xishanping site in Gansu shows that the rice has been cultivated about 5 000 years ago in Tianshui, Gansu province. The finding of cultivated rice with accurate dating is known the oldest record, which is also the most northwest border of cultivated rice, in northwest China. The finding extends the record of cultivated rice about 2°of longitude to the west and allows us to estimate the cultivated region of rice 5 000 years ago in Easern Asia. It will help on understanding the affection of rice cultivation and spreading on agriculture and environment.

AP2/ethylene responsive-element binding proteins (EREBPs) comprise a superfamily of AP2/EREBP domain-containing transcription factors that exist extensively in plants. They are involved in plant development and stress responses. An estimated 150 AP2/EREBP genes exist in Orzya sativa; however, most have not been characterized. To investigate the gene expression profile at the transcriptional level, we retrieved and amplified 32 putative AP2/EREBP genes from the rice genomic database on the basis of AP2/EREBP domain sequencing from Arabidopsis. The sequences of these putative genes were amplified by PCR for macro-array analysis. Results of hybridization of these putative genes with probes from different organs of O. sativa suggested that the level of expression of AP2 subfamily members differed; however, most were expressed consistently in different organs of O. sativa. On the contrary, most of the putative EREBPs were expressed intensively in young roots and mature leaves but much less in young buds and young leaves. The patterns of expression of these genes may be related to their functions.

Plants can sense changes in soil water status before obvious water deficit occurs in shoots. Abscisic acid(ABA) and pH are key signals mediating root-to-shoot signaling. Here we report that drought leads to changes in xylem pH differently in Commelina communis L., tomato(Lycopersicon esculentum Mill.) and sunflower(Helianthus annuus L.). The drought-induced changes in pH were not related to changes in xylem nitrate content. However, for the plant species tested, nitrate was able to increase the stomatal sensitivity to ABA in detached leaves. Moreover, root-splitting experiments demonstrated that supplying extra nitrate in soil increased the stomatal sensitivity to root-sourced soil-drying signals when the nitrate concentration in the xylem was lifted. Our results suggest that nitrate can enhance the root signal and thereby jointly regulate stomatal movement under drought stress.

Trehalose-6-phosphate synthase(TPS), which plays an important role in the synthesis of trehalose has received much attention in recent years. Research into TPS has mainly focused on bacteria and fungi. However, little research in plants has been reported. This paper describes the cloning and functional analysis of TPS from Arabidopsis. The Arabidopsis cDNA sequence of TPS in the pET30a(+) vector was heterogeneously overexpressed in BL21 of E. coli. Then, TPS was cloned into the plant expression vector pBI121 and transformed into tobacco. The expression of target gene in the transgenic tobacco plants was confirmed with real-time PCR. The transgenic tobacco line S5 showed higher trehalose level, which enhances the tolerance of transgenic plant to salt stress.

The vegetation in Tai Lam Country Park, Hong Kong, was investigated in 35 sampling plots. Unw eighted pair-group method with arithmetic averages (UPGMA) and detrended correspondence analysis (DCA) were used to classify the forest communities into 7 types (Acacia confusa Merr. Comm., Lophostemon confertus (R. Br.) Peter G. Wilson ex J. T. Waterh Comm.,Schima superba Gardner ex Champ. Comm., Eucalyptus citriodora Hook. Comm., Pinus elliottii Engelm.+ Schefflera octophylla (Lour.) Harms . Comm., Aquilaria sinensis (Lour.) Spreng. and Eucalyptus torelliana F. Muell. Comm.) and shrub communities into 4 types (Acronychia pedunculata (L.) Miq.+ Phyllanthus cochinchinensis (Lour.) Spreng., Li tsea rotoundifolia (Nees) Hems l. var.oblongifolia (Nees) C. K. Allen + Rhodomyrtus tomentosa (Alton) Hassk. Comm., Gordonia axillaris (Roxb ex Ker Gaw l.) D. Dietr.,and Rhodomyrtus tomentosa (Alton) Hassk.+Dicranopteris dichotoma (Thunb.) Bernh. Comm.). DCA ordination revealed a weak relation between altitude and spatial distribution of species. The first axis of the DCA ordination indicated the humidity gradient and correlated with the diversity index scores of species. The diversity index showed that the species in most plantations had some tolerance to shade. Tristania conferta R. Br. plantations and a few Acacia confuse Merr. plantations had light-demanding species. The investigation showed that the east region in the park is more suitable for plant growing. In the west part of the park, the plants are mainly composed of plantation species and shrubs, with the diversity and richness indices of the plant community in this area lower. Because of poor soil and repeated fire, most shrub communities were at their pioneer succession stage.

The major traits — number of tillers , number of effective tillers, plant height, etc. — of the F2, F3 and F6 progenies derived from the rice subspecies cross Pei'ai64s/Nipponbare underwent ANOVA and correlation analysis. Both parents significantly differed in traits, with great differences in phenotypic values at different locations and years. The phenotypic coefficients of variation for plant height varied greatly, from 14.4% to 22.8%. The frequency distribution of all traits, except for percentage of tillering for F2 progeny, days to heading for F3 and plant height for F6, was fairly normally distributed. Progeny also showed tremendous bidirectional segregation beyond parents for all traits . The correlations among all traits varied slightly, but the direction of variance was relatively stable. These results provide some meaningful information for mapping of quantitative trait loci and genetic improvement for rice breeding. The research implications of agronomic traits with sequenced rice varieties as parents are discussed.

Synechocystis sp. PCC6803 and Microcystis aeruginosa were treated with the dopant nano TiO2 components 1% Ag,5% Fe2O3, 10% ZnO, and nano TiO2 alone under natural illumination and fluorescent conditions . We determined the content of chlorophyll a, carotenoids, extracellular O2 -. and superoxide dismutase activity in samples. The natural illumination condition was more effective than the fluorescent condition in the photocatalysis of nanometer material. The dopant nano materials were more effective than nano material alone in inhibiting growth of blue-green algae, 1% Ag having the best inhibitory effect. M. aeruginosa has a stronger ability to adapt to superoxide anion stress produced by photocatalysis of nano TiO2 than Synechocystis sp.

The formation and development of sporoderm of the fern Ceratopteris thalic troides (L.) Brongn. (Parkeriac eae) were studied by means of light microscopy, scanning electron microscopy and transmission electron microscopy. The mature spores are radially symmetrical and trilete. The surface of spores is smooth and shows a rib-shaped (costate) ornamentation. The sporoderm consists of endospore, exospore and perispore. The exospore, which is formed by sporopollenint, is prominent; it is about 3-5 μm thick, and its rib-shaped ridges are about 5-7 μm high. The surface is smooth and the texture is uniform. The perispore is formed by the tapetal residues, which deposit on the outside of the exospore. The perispore is very thin, about 0.1 μm thick, with many small rod-like projections in the surface of perispore. The results will contribute to a better understanding of the origin, development and formation process of the sporoderm of ferns. They can also provide basic information about the palynology and phylogeny of ferns.

Choline oxidase gene (codA) was introduced into the haploid plants of Populus simonii × P. nigra by Agrobacteri ummediated approach, with axenic leaves used as explants. PCR and Southern blot analysis confirmed four kanamyc in-resistant transgenic plants, in which codA successfully integrated into the genome of Populus simonii × P. nigra haploid plants. Real-time quantitative PCR revealed that the transgene was expressed in the transgenic plants at different levels. Salt tolerance test demonstrated that the 4 transgenic plants could grow normally at 0.6% salinity, but nontransgenic plants suffered severely from the same salinity. Thus, the expression of codA gene improves the salt-stress tolerance of these transgenic poplar plants.

We used somatic embryogenes is to regenerate snow lotus (Saussurea involucrata Kar.et Kir.). For induction of calli,cotyledons were cultured on solid MS medium with 0.5 mg.L-1 2,4-D and 0.05-1 mg.L-1 BA. Globe-shaped yellow is h-green calli were chosen from the first subculturing for suspension culture in liquid MS medium containing 0.05-0.1 mg.L-1 2,4-D. After 20 days of culture, many globular embryoids were produced. Polyethylene glycol and gibberellic acid (GA) were added during subculture for differentiation and growth of somatic embryos. Plantlets were regenerated when somatic embryos were transferred to MS medium with 5 mg.L-1 GA3.

APETALA2/ethylene responsive-element binding proteins (AP2/EREBPs) are an ancient superfamily of transcription factors. AP2/EREBPs are distinguished by containing one or two conserved DNA binding domains, the so-called AP2/ERF DNA binding domain, which consists of approximately 60-70 amino acid residues. According to the number of AP2/ERF domains, the AP2/EREBP family is divided into two subfamilies : EREBPs, which contain one AP2/ERF domain, and AP2s, which contain two AP2/ERF domains. The main function of the AP2 subfamily is regulation of development of flowers, ovules, and seeds etc., and the EREBP subfamily plays important roles in regulating the response to plant hormones (ethylene, ABA etc.) , pathogen attack and stresses (cold, drought and high salt etc.). This paper reviews the progress of research into the AP2/EREBP family of transcription factors in the development and stress response of plants.

DNA methylation is one of the most important issues in epigenetics and plays a key role in plant research. This review introduces the progress of research into the mechanisms of DNA methylation, such as histone methylation, RNA-dependent DNA methylation, and demethylation, and discusses the functions of DNA methylation in plants, including defending the genome against transposons and regulating gene expression. The role of DNA methylation in transgene silencing and epigenetics is covered, as is approaches to study DNA methylation in plants, including high performance liquid chromatography, bisulphite sequencing, methylation- sensitive amplified polymorphisms, restriction enzyme digestion and Southern blot analysis.

In recent years, gene trapping mediated by T-DNA has provided a pow erful tool to isolate and identify genes. As the sequencing of the Arabidopsis and rice genomes has been completed, gene trapping mediated by T-DNA is likely to play an increasingly important role in determining gene function. In this review, we describe the types of gene trapping mediated by T-DNA,the advances in gene cloning, and the mutant pool and its applications. Problems in plant functional genomics are also discussed.

The phenomenon ‘somaclonal variation’ refers to genetic and/or epigenetic changes in cells or regeneration that arise through the culture of plant cells, tissues and organs. Some genetic bases underlye the plant somaclonal variation, which can be integratively determined and identified at morphological, cytological, biochemical and molecular biological levels. Plant somaclonalvariation is one of available resources in plant breeding, but it is an unw elcome puzzle to be won through in plant micropropagation in vitro and genetic transformation. This paper reviews the progress in study of the genes is and identification of plants omaclonal variation at both cytological level and molecular biological level, and discusses the problems and prospects of applying somaclonal variation in breeding and improving plant varieties.