Cloning and expression analysis of the FvNCED3 gene and its promoter from ash(Fraxinus velutina)

The 9-cis-epoxycarotenoid dioxygenase(NCED)gene is rate-limiting in abscisic acid(ABA) biosynthesis.In this study, an NCED gene, designated FvNCED3(KY008746), was cloned from velvet ash(Fraxinus velutina Torr.) with a RACE method. The full length c DNA of FvNCED3 encodes a 573-amino acid polypeptide.Sequencing analysis showed that the FvNCED3 protein was highly homologous to other NCED proteins. The expression patterns of FvNCED3 in different ash organs were analyzed by real-time PCR which revealed that FvNCED3 expression levels were highest in leaves and lowest in roots. The gene expression patterns of FvNCED3 under abiotic stress indicated that its expression increased under drought, salt and ABA stress and decreased due to high and low temperatures. There were no obvious changes under ultraviolet light. The 1094-bp upstream sequence 5' flank regulation region of the FvNCED3 gene was also cloned from ash using the Genome Walking method. To assess the activity of the FvNCED3 promoter, a p FvNCED3 p::GUS plant expression vector was constructed for tobacco transformation. GUS expression of the FvNCED3 GUS enzyme activity was detected in almost all transgenic tobacco tissues, especially in the young leaves,stigma, anther, ovule and ovary. After treating the transgenic tobacco with NaCl and placing it under drought stress, GUS staining of tobacco leaves increased compared with that under normal growth conditions. This result indicates that gene expression driven by the FvNCED3 promoter can be induced by salt and drought stress.

Photosynthetic and water-related physiological characteristics of Periploca sepium in response to changing soil water conditions in a shell sand habitat

This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats.Four-year-old Periploca sepium seedlings were used as model species.A gradient of 12 water levels was established by artificially supplying the shell sand with water up to saturation and then allowing natural evapotranspiration to occur.The photo synthetic,chlorophyll fluorescence and stem sap flow parameters of P.sepium were measured under a range of water conditions.The different soil water conditions were classified according to the responses of these parameters.(1)With the increase in the relative water content(RWC)of the shell sand,the parameters of leaf photosynthesis,chlorophyll fluorescence and water-related physiology in P.sepium showed significant critical responses.The net photo synthetic rate(Pn),transpiration rate(Tr),instantaneous water use efficiency(WUE),potential water use efficiency(WUEi),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(ΦPSII)and daily accumulation of stem sap flow all increased first and then decreased with increasing RWC,but the corresponding water conditions associated with their maximum values were not the same.An RWC of 69.40%was determined to be the optimal water condition for photosynthesis and water-related physiological activity in P.sepium.At an RWC of 36.61%,the mechanism of photosynthetic inhibition in P.sepium changed from stomatal limitation to nonstomatal limitation;this was also the minimum water requirement for maintaining normal photo synthetic processes.An RWC of 50.27%resulted in the highest WUE in P.sepium,indicating that moderate drought stress increased WUE.(2)Based on the quantitative relationship between the photo synthetic parameters of P.sepium and the shell sand water gradient,the soil water availability was classified into 6 water grades.The RWC range for maintaining strong photosynthesis and high WUE in P.sepium was 63.22-69.98%.(3)Gas exchange in P.sepium was inhibited under drought and waterlogging stresses.Under these conditions,the photosynthetic electron transport chain was blocked,and the dissipation of light energy as heat increased,which ultimately led to a decline in photo synthetic productivity;moreover,transpiration and dissipation were aggravated,and water transmission and utilization processes in P.sepium were hindered.A significant negative feedback regulation mechanism in the photosynthetic and water-related physiological processes of P.sepium was observed;this mechanism allowed P.sepium growing in shell sand to be highly adaptable to water stress.

Genetic variation in growth traits and stem–branch characteristics and their relationships to Eucalyptus clones

Eucalyptus has become an important genus in China because it displays adaptability to a wide range of site conditions and produces pulp wood and veneer on short rotations. The aim of this study was to estimate genetic parameters and relationships and consider impli- cations for development of clonal forestry. We assessed growth traits, stem-branch characteristics, crown diameter and height of fresh branch for 20 Eucalyptus hybrid clones in China measured at the age of 44 months. Analysis of variance showed that there were significant differences in growth traits, height of fresh branch and stem straightness among clones. Significant differences in height, volume, crown diameter, height of fresh branch and branch size among replicates were also recorded. Coefficients of vari- ation ranged from 9.84 to 28.54 % for growth traits, 12.03 to 17.25 % for stem-branch characteristics, 18.26 % for crown diameter and 11.73 % for height of fresh branch. Estimates of repeatabilities for height, diameter at breastheight over bark, volume, crown diameter, height of fresh branch, stem straightness and branch size at clone mean level were 0.86, 0.80, 0.80, 0.54, 0.85, 0.77 and 0.44 respectively. Diameter at breast height over bark and height had strongly positive phenotypic and genotypic correlations with volume, ranging from 0.96 to 1.00. The positive genotypic and phenotypic correlations between growth traits and other studied traits suggested that fast growing clones always had bigger crown diameter, higher height of fresh branch, straighter stems and relatively smaller branches.

Heterosis Estimation for Growth Traits and Wood Properties of Eucalyptus urophylla under Two Sites in Southern China

Heterosis is a quicker,cheaper and easier method for increasing plantation production,and heterosis studies can provide the basis for exploitation of valuable hybrid combinations in breeding programs.Growth traits,wood properties,and bark percentage were assessed for 6×6 full diallel progenies of E.urophylla in southern China measured at age 4 years.Analysis of variance showed that there were significant differences on all studied traits except dynamic modulus of elasticity among combinations.The mean diameter at breast height,wood basic density,and dynamic modulus of elasticity were 9.40 to 12.20 cm,0.45 to 0.47 g cm-3,and 5.04 to 5.72 GPa,respectively.The coefficients of variation ranged from 18.18%to 50.43%for growth traits,9.07%to 55.24%for wood properties and 22.26%to 23.93%for bark percentage.The heterosis estimation on diameter at breast height,wood basic density,and dynamic modulus of elasticity were-24.07%to 18.74%,-14.23%to 9.17%and-25.53%to 16.28%.U22×U56 generally had higher heterosis of growth traits and wood properties through three sites.Same combinations had different original and reciprocal heterosis estimation at two sites even on same traits.The combinations of same parents always had similar original and reciprocal heterosis estimation.

Present Situation of Eucalypts Breeding and Future Prospect in China

Breeding is the major procedure in forest research.The basic goal in all of breeding program is to expand the frequency of favorable alleles or the frequency of specific combinations of favorable alleles in the breeding populations through recurrent selection in order to improve the performance of individual plants.During the past three decades,an increase in research on breeding has improved Eucalyptus productivity,and to some extent our standing of their effects on tree growth and on wood properties.Unfortunately,very little information about breeding on the review of Eucalyptus grown in China has been published even though this species was introduced some 120 years ago.This paper reviews the available information regarding research status and prospect of breeding under Chinese ecological conditions and to outline some suggestions to them.According to the present research situation of breeding,we would recommend that:generalizing empirical and useful practices;developing highvalue products;creating more clones for demand;carrying out intensively research over different species and clones for different cultivation goals at different sites over time;above all,applying breeding strategy,especially for multiple generations and interspecific hybrid breeding.

Effect of organic materials on the chemical properties of saline soil in the Yellow River Delta of China

A 180-day incubation experiment was con- ducted to investigate the effect of different organic materials on the chemical properties of coastal soil with high salinity and relatively low pH. Four organic materials （three kinds of plant residues： straw, composted straw, and fresh reed; and one kind of poultry manure： chicken manure） were applied at a ratio of 15 g·kg^-1 to samples of costal saline soil from the Yellow River Delta of China. The results showed that the soil pH and exchangeable sodium percentage （ESP） decreased, whereas soil cation exchangeable capacity （CEC） and macronutrient concen- trations increased, regardless of the type of organic material used. All treatments showed a remarkable increase in soil soluble organic carbon （SOC） during the 180-day incubation. The peak values of SOC in descend- ing order were chicken manure, reed, composted straw, straw, and control soil. At the end of incubation, the highest level of SOC occurred in the straw-amended soil, followed by composted straw, reed, and chicken manure- amended soils. Soil respiration rate and available nitrogen were significantly influenced by the type of material used. Although reed-amended soil had a relatively high SOC and respiration rate, the ESP was reduced the least. Consider- ing the possible risk of heavy metals caused by chicken manure, it is proposed that straw and composted straw are the more efficient materials to use for reclaiming costal saline soil and improving the availability of macronu- trients.

Vegetation pattern in Shell Ridge Island in China＇s Yellow River Delta

In general, coastal habitat conditions are extremely harsh, with the ecological equilibrium inextric- ably related to the plant community. Understanding the natural vegetation features of a coastal zone with little human disturbance could provide a reference for future vegetation restoration and ecosystem maintenance ser- vices. In this study, the vegetation patterns of Wangzi Shell Ridge Island in the Yellow River Delta were investigated. A total of 35 taxa of vascular plants were documented, representing 15 families and 33 genera （of which most were mono-specific）. Surveys identified only one to eight taxa in each plot. From sea to land, the vegetation showed a typical zonal distribution pattern. There was a correlation between the landform and important factors that influenced the plants including soil factors and distance from the sea. Thus, the taxa distribution and vegetation had a significant correlation with landform. The dune crest, backdune and interdune lowlands were areas with weak storm surges and were the important locations for the taxa to be become established. Plants along the high-tide line formed important defenses from large waves and high winds. The significant protection provided a suitable living environment for many organisms with high medicinal value. Special attention and protection could be provided to this area by reducing the use of the beach road and enclosing the complete section from sea to land with a protective fence. In addition, vegetation protection and restoration on Shell Ridge Island would aid in the formulation and implementation of reintroduction strate- gies for similar vegetation in similar habitats.

Topsoil dichlorodiphenyltrichloroethane and polychlorinated biphenyl concentrations and sources along an urban-rural gradient in the Yellow River Delta

The Yellow River Delta （YRD） is a typical agricultural and petrochemical industrial area of China. To assess the current status of soil dichlorodiphenyltrichloroethane （DDT） and polychlorinated biphenyls （PCB） residues, topsoil samples （0-15 cm） （n = 82） were collected in Bincheng District, at the geographic center of the YRD. The total concentrations of six DDT homologues were within 3.3-3819 ~tg/kg, with a mean concentration of 191 ~tg/kg, showing significant increase along urban-rural gradient. Soil concentrations of seven indicator PCBs in the area ranged from non-detectable to 87.0 ~g/kg, dominated by heavily chlorinated PCBs （PCB-101 and -118）. Soil PCBs concentrations were significantly greater in urban than suburban and rural areas. Principal component and multiple linear regression analysis suggest that 86.4% of soil DDTs originate from past DDT usage, and 13.6% originate from dicofol application. Soil PCBs most likely originate from the petrochemical industry （77.1%）, municipal solid waste disposal （16.5%）, local commercial PCB homologues usage （5.2%）, and long-range atmospheric deposition （1.2%）. In general, soil DDTs pollution was classified as low level, and mean PCBs concentrations were below the severe contamination classification range. Because PCB-118 is a dioxin-like congener, monitoring and remediation is advised to assess and reduce negative environmental and human health effects from soil DDTs and dioxin-like congeners in the study area.

Flora characteristics of Chenier Wetland in Bohai Bay and biogeographic relations with adjacent wetlands

A key step towards the restoration of heavily disturbed fragile coastal wetland ecosystems is determin- ing the composition and characteristics of the plant communities involved. This study determined and char- acterized the community of higher plants in the Chenier wetland of Bohai Bay using a combination of field surveys, quadrat approaches, and multivariate statistical analyses. This community was then compared to other adjacent wetlands （Tianjin, Qinhuangdao, Laizhouwan, Jiaozhou- wan, and Yellow River Delta wetland） located near the Huanghai and Bohai Seas using principal coordinate analysis （PCoA）. Results showed a total of 56 higher plant species belonging to 52 genera from 20 families in Chenier wetland, the majority of which were dicotyledons. Single-species families were predominant, while larger families, including Gramineae, Compositae, Leguminosae, and Chenopodiaceae contained a higher number of species （cache〉6 species）. Cosmopolitan species were also dominant with apparent intrazonality. Abundance （number of species） of temperate species was twice that of tropical taxa. Species number of perennial herbs, such as Gramineae and Compositae, was generally higher. Plant diversity in the Chenier wetland, based on the Shannon- Wiener index, was observed to be between the Qinhuang- dao and Laizhouwan indices, while no significant difference was found in other wetlands using the Simpson index. Despite these slight differences in diversity, PCoA based on species abundance and composition of the wetland flora suggest that the Bohai Chenier community was highly similar to the coastal wetlands in Tianjin and Laizhouwan, further suggesting that these two wetlands could be important breeding grounds and resources for the restoration of the plant ecosystem in the Chenier wetland.