Abstract:Degenerate primers based on conserved motif （P-loop and GLPL） of the nucleotide binding site （NBS） region from the cloned plant disease resistance genes were used to isolate resistance gene analogues （RGAs） from genomic DNA of the sweet potato （Ipomoea batatas （L.） Lam.） cultivar Qingnong No. 2. The desired bands （～500 bp） were purified fi＇om the gel, and then cloned by T/A cloning. After sequencing and analyzing by alignment, 15 RGAs with uninterrupted open reading flames （ORFs） were obtained. Sequence identity among the 15 RGA nucleotide sequences ranged from 41.2% to 99.4%, while the 15 RGAs deduced amino acid sequences showed identity ranged from 20.6% to 100%. The phylogenetic analyses for RGA nucleotide sequences and the deduced amino acids showed that RGAs from sweet potato were divided into two groups, TIR （Drosophila Toll or human interleukin receptor-like） type and nonTIR type. The analysis of RGAs amino acid sequence structures suggested that they contained the domains such as P-loop, Kinase-2, Kinase-3a, and GLPL. These results showed that NBS type RGAs isolated from sweet potato might have the same origin and mechanism of evolution as that in other plants.

Abstract:A total of 95 rice varieties were collected including four compatibility groups of indica compatible varieties （ICV）, japonica compatible varieties （JCV）, wide compatible varieties （WCV） and incompatible varieties （NCV）. Genetic variation and genetic structure among the four groups were evaluated by using isozyme markers. Ten isozymes gave rise to 55 alleles in 34 loci of which 15 （P = 44.12%） were polymorphic. The average expected heterozygosity ranged from 0.354 to 0.456 at the group level, and 0.454 at the species level. AMOVA analysis showed that 80.21% of genetic variance distributed within groups, and only 19.79% among groups. The variation of genetic distance between groups ranged from 0.1129 to 0.3673, and the gene flow ranged from 1.0242 to 2.5451. UPGMA cluster analysis based on Nei＇s genetic distance could divide the four groups into two clusters:( Ⅰ ) wcv and JCV, ( Ⅱ ) ICV and NCV.

Abstract:Agrobacterium-mediated transformation of Citrus medicaL, var. sarcodactlis was performed by leaf disc. The binary vector harbors the gene of interest TPS and NUFII gene driven by CaMV 35S promoter. The presence of TPS gene integration in the genome was detected and confirmed by GUS assay and PCR, respectively. Transformation parameters optimized were bacterial concentration, pre-culture period, immersion time, concentrations of antibiotics （cefotaxime, Cef and carbenicilline, Cb） and reagents （acetosyringone, AS and L-cysteine, L-Cys）. Results were obtained based on the percentage of GUS positive transient expression. A. tumefaeiens strain LBA4404 at OD_{600 nm} 0.6 showed the highest virulence on the leaf explants of C. medica with 20 rain of immersion. Two to three days ofpre-culture on MT medium in dark and 3 days of co-cultivation were optimum for C. medica. The mixture containing 250 ml L^-1 Cefand 250 ml L^-1 Cb gave the highest rate of callus induction for C. medica. Addition of 100 μ mol/L AS and 400 mol/L L-Cys enhanced the transformation efficiency of C. medica. Under the optimal condition, the percentage of GUS transient expression was 5.9%.transformation; Trehalose synthase gene.

Abstract:Photosynthetic characteristics in leaves of Castanopsis hystrix saplings in Longyandong Forestry, Guangzhou, were studied during early summer and autumn under natural conditions by leaf gas exchange and chlorophyll fluorescence techniques. The light saturation point （LSP） of sun leaves in canopy was 400 μ mol photons m^-2s^-1, and the maximum net photosynthetic rate was 4-6 μ mol m^-2s^-1. These data showed that C. hystrix saplings are sun plants. The values of chlorophyll a/b in sun leaves and shade leaves were both upto 2.4, and the content of chlorophyll b in shade leaves was higher than that in sun leaves, indicating that shade leaves in canopy had the potential ability to utilize low light intensity. The daily changes in chlorophyll fluorescence parameters recorded that maximum photochemical efficiency of PSⅡ(Fv/Fm) and photochemical quantum yield of PS Ⅱ (Yield) in sun leaves of C. hystrix canopy declined slightly at the midday, suggesting the occurrence of reversible photoinhibition. Owing to the lower maximum net photosynthetic rate in sun leaves and the ability to effectively and consistently utilize the scattered light and/or transmitted light, C. hystrix saplings could survive low light intensity, grow well at the edge of the forest and in the understorey, and eventually become one of the dominant species in upper layer of the community.

Abstract:Simulation experiments were undertaken to analyze the difference ofLarrea tridentata desert ecosystem in Phoenix, USA responses to elevated atmospheric CO₂ concentration between dry and wet years. A physiologicalbased ecosystem model, PALS-FT was used in the simulation analysis. Aboveground net primary productivity （ANPP） and annual accumulation rate of soil organic matter （SOM） increased nonlinearly with increasing [CO₂] in wet years, but linearly in normal and dry years, while N content in soil （N_soil） decreased nonlinearly with increasing [CO₂] in all types of years. The absolute changes of ANPP and SOM were always larger in wet years than in normal and dry years, and the relative changes of them were dependent greater on the [CO₂] level of interest rather than on year types （i.e., wet, normal, and dry years）. However, both the absolute and relative changes of Nsoil were always larger in wet years than in normal and dry years. The absolute changes of ANPP in different plant functional types （PFTs） responding to elevated [CO₂] were larger in wet years than in normal and dry years, but the relative changes varied also PFT-specifically. Shrub and subshrub FTs showed larger responses in dry years, whereas C₃ and C₄ annuals showed larger responses in wet years. Therefore, responses of desert ecosystems to a future elevated CO₂ would be markedly influenced by precipitation patterns.

Abstract:The Parakmeria omeiensis trees of 10 years treated by cutting root and branch in the spring, summer and autumn, 2005, were compared with those untreated in photosynthesis and transpiration to discuss the effects of physiological factors on the transplant survival rate in different seasons. In the spring, stomatal conductance sharply declined in the treatment, followed by decreasing transpiration and photosynthetic rates with the lowest rates as much as about 60% of those in the control, causing a small portion of water lost from the plants. The weakening in physiological function contributed to the transplant survival rate by metabolism balanced between underground and aboveground. In the summer, transpiration and photosynthetic rates significantlyincreased with stomatal conductance in the treatment. And the highest rates of transpiration and photosynthesis were about double those in the control, suggesting a great amount of water loss. The low transplant survival rate occurred because the lost water could not be compensated enough mainly by cutting branch. In the autumn, the treated plants were higher in stomatal conductance, transpiration and photosynthetic rates than the control. But the increments of both transpiration and photosynthetic rates were slight, relative to those in the summer, and the highest rates were 40% higher than those in the control shortly after treatment. The transplant survival rate could be improved by properly cutting branch or increasing water content in soil. It is concluded that the transplant survival rate is determined by altering physiological function relate to water metabolism, viz, plants capable of reducing water loss by rapidly manipulating their own physiological function have higher transplant survival rate, vise versa.

Abstract:The essential oils were extracted from the aerial parts of Cinnamomum japonicum Sibe by steam distillation and determined by GC-MS. Twenty-seven chemicals were isolated. Borneol was the major component accounting for 26.03% of the total oil. The essential oils exhibited significant activity against Escherichia coli, Bacillus subtilis and Staphylococcus aureus in the filter paper assay.

Abstract:The fatty acids from the seeds of Raphanus sativus were extracted with petroleum ether by Soxlet extraction. The extracted fatty acids were esterified and analyzed by gas chromatography-mass spectrometry. Twelve fatty acids were detected and identified, amounting to 99.32% of the total fatty acids, mainly including 13-docosenoic acid （32.47%）, 9-octadecenoic acid （29.07%）, 9,12-octadecadienoic acid （Z,Z） （9.45%）, 9,12, 15-oetadecatrienoic acid （8.41%）, hexadecanoic acid （4.31%）, and octadecanoic acid （2.08%）. The saturated fatty acids and unsaturated fatty acids were 9.25% and 90.07% in amount, respectively.

Abstract:Five phenolic compounds, quercitrin （1）, myficitrin （2）, afzelin （3）, (＋)-gallocatechin （4）, and 3-chloro-4-hydroxybenzoic acid （5）, together with daucosterol （6）, were isolated from ethyl acetate fraction of ethanol extract ofA ilanthus fordii twigs. Their structures were elucidated by spectroscopic evidence （IR, NMR, MS, etc） and comparison of their spectral data with those of the literatures. Compounds 1-5 were isolated from this genus for the first time.

Abstract:The volatile oil from the rhizome ofHedychiumforrestii Diels was extracted by steam distillation and analyzed by capillary gas chromatography-mass spectrometry. Sixty peaks were obtained, of which 51 compounds were identified, accounting for 97.32% of the total oil. Monoterpenoids and sesquiterpenoids consisted of a large number of chemical components in the volatile oil.

Abstract:The pedicel segments from Narcissus tazetta var. chinensis were treated with IAA and GA3 for 48 hours, and the length of the segment elongation was determined. The interactions between the two hormones were also discussed. Both 50 μ mol/L IAA and 30 μ mol/L GA₃ were found to promote the elongation of pedicel segments. Moreover, IAA performed more effectively than GA₃. Both 2,3,5-triiodobenzoic acid (TIBA) (an IAA polar transport inhibitor) at 200 μmol/L and uniconazole (S-3307) (a gibberellin biosynthesis inhibitor) at 65 μ mol/L significantly inhibited the elongation of pedicel segments. Following the 50 μ mol/L IAA treatment GA₁₊₃ content in the segments increased 3.4-fold as much as that in the control, whereas IAA content in the segments treated with 30 μmol/L GA₃ was slightly varied. It is suggested that IAA plays an important role in maintaining the level of active GA in pedicels and regulates the elongation of the pedicel segments together with GA.

Abstract:Following the low dose of chlorine dioxide （1.0, 1.5,2.0,2.5 mg L^-1） treatment of Phaeocystis globosa for 96 h and the high dose （2.5,6.0,8.0, 16.0 mg L^-1） treatment for 60 min, the contents of chlorophyll a, proteins, amino acids and DNA in cells were determined. Meanwhile, changes in cell morphology after 24 h treatment of chlorine dioxide （0.5 mg L^-1, 0.8 mg L-^-1） was observed by transmission electron microscope. Contents of chlorophyll a, proteins and DNA in the treated P. globosa were lower than those in controls. In the present of chlorine dioxide over 2.0 mg L^-1, chlorophyll a, proteins, DNA in content and cysteine, tyrosine, lysine in relative percentage remarkably decreased, whereas histidine, valine and phenylalanine in relative percentage increased. The leakage rate of DNA was in the range of 13%-18% after treated with chlorine dioxide of 2.5-16.0 mg L^-1 for 3 min. We observed that the substance damaged the cell membranes, causing the leakage of cellular content. These results suggested that chlorine dioxide might deform chlorophyll a and proteins in P. globosa by single molecular diffusion, damage the cell membrane system by lipid peroxidation, and eventually led to the death of cells.

Abstract:The vessel element in the secondary xylem of Casuarina cunninghamiana was observed under an electron microscope. Three types of the vessel elements were found, a tail on each side, one tail only and no tail. Four types of perforation plates were present as follows： the scalariform perforation plate, the simple perforation plate, the scalariform-simple perforation plate, the simple and scalariform perforation plates symmetrically arranging on the same side of vessel, as well as some transitional types. The evolution of perforation plates in the vessel elements is discussed.

Abstract:Ficus and their species-specific pollinator wasps （Agaonidae） form a remarkable plant-insect obligate mutualism. The studies on co-evolution of them caused much attention to the classification of Ficus. For further study of the systematics and evolution of the genus, the present authors introduce the taxonomic history and some known classification systems in this review. In addition, some unresolved problems in Ficus taxonomy are discussed and some advices on the future study are given.

Abstract:miRNAs are approximately 22-nucleotide endogenesis noncoding regulated RNAs in eukaryotes that have phosphate group at 5＇end and hydroxy group at 3＇end, which attract extensive attention in recent years. Scientists are now on the threshold of a better understanding how miRNAs works, miRNAs plays an important role in controlling plant development, florescence time, metabolism, response to stress, etc. Plant miRNAs are known to repress gene expression post-transcriptionally, mainly by guiding mRNA cleavage but also by attenuating the translation of target transcripts. In addition, it has been shown that plant miRNAs can also act at the transcriptional level by directing the methylation of target chromosomal loci. This paper reviews recent researches on the function and mechaism of plant microRNA.

Abstract:miRNAs are approximately 22-nucleotide endogenesis noncoding regulated RNAs in eukaryotes that have phosphate group at 5＇end and hydroxy group at 3＇end, which attract extensive attention in recent years. Scientists are now on the threshold of a better understanding how miRNAs works, miRNAs plays an important role in controlling plant development, florescence time, metabolism, response to stress, etc. Plant miRNAs are known to repress gene expression post-transcriptionally, mainly by guiding mRNA cleavage but also by attenuating the translation of target transcripts. In addition, it has been shown that plant miRNAs can also act at the transcriptional level by directing the methylation of target chromosomal loci. This paper reviews recent researches on the function and mechaism of plant microRNA.