Constitutive expression of sense &; antisense <Emphasis Type="Italic">PtAP3</Emphasis>, an <Emphasis Type="Italic">AP3</Emphasis> homologue gene of <Emphasis Type="Italic">Populus tomentosa</Emphasis>, affects growth and flowering time in transgenic tobacco

To analyze the function of PtAP3, an APETALA3 （AP3） homologue gene isolated from Populus tomentosa Carr., the full length sequence （1797 bp） and a fragment （870 bp） of PtAP3 were fused to a CaMV 35S promoter of pBI121 to generate the sense and antisense constructs of PtAP3. These constructs were transformed into tobacco by Agrobacterium infection of leaf disks and selection on kanamycin medium. Some sense and antisense transgenic tobacco plants were obtained by PCR and Southern blot analysis. Great phenotypic differences in transgenic tobacco plants were observed. Almost all of sense PtAP3 to transgenic tobaccos showed a higher growth rate than those of antisense transformants and a few developed pregnancy earlier than wild type seedlings and antisense transformants under the same conditions.     

RAPD markers related to sex locus in Populus tomentosa

By using the methods of random amplified polymorphic DNA (RAPD) and bulked segregate analysis (BSA), we identified markers that are linked to the sex determination in the dioecious Populus tomentosa. Male and female bulks were created through rough mixing equal amounts of its five individual DNA. A total of 88 primers were screened. Twelve primers produced clear patterns with at least one band that appeared to be polymorphic between the two bulks. Subsequently, five male and female individuals were analyzed with those 12 primers, and only S60 (ACCCGGTCAC) could generate a common 1800 bp DNA fragment in all five male individuals and male pool but not in any female individuals. It can be concluded that the gender of P. tomentosa is most likely connected to the S60-1800 bp DNA fragment and RAPD markers. S60, therefore, can be used for selecting the gender of P. tomentosa. __________ Translated from Journal of Central South University of Forestry & Technology, 2008, 28(3): 80–83 [译自: 中南林业科技大学学报]     

Steady-state nutrition of hybrid poplar grown from un-rooted cuttings

Fertilizing plantations of fast-growing tree crops, in manners which supply nutrients at rates that match plant demand and maintain stable internal plant nutrient ratios, can maximize biomass production and carbon sequestration while reducing fertilizer wastage and pollution. Our objectives were to determine nutrient ratios of common hybrid poplar (Populus trichocarpa Torr. and Gray × Populus deltoides Marsh.) (T × D) clones under steady-state nutrition, and to determine if incremental additions of fertilizer were more successful than conventional (evenly-split) fertilizer additions in maximizing biomass production and inducing stable nutrient ratios. Un-rooted cuttings of three T × D clones (49–177, DTAC-7, 15–29) were grown under a conventional regime and a modified-exponential fertilization regime at three application rates (1.8, 3.7 or 7.4 g N plant⁻¹). Above- and below-ground biomass and nutrient concentrations were measured after one growing season. There were few differences in total plant biomass between conventional and modified-exponential fertilization regimes, but for one clone, biomass accumulation equivalent to the highest rate under the conventional regime was achieved with the medium rate of the modified-exponential regime. Stable nutrient ratios (at conditions consistent with steady-state nutrition) were: 100N:14P:50K (49–177), 100N:13P:49K (DTAC-7) and 100N:12P:60K (15–29).     

Cloning and RNAi construction of a LEAFY homologous gene from Populus tomentosa and preliminary study in tobacco

PtLFY, a LEAFY (LFY) gene, was cloned from Populus tomentosa (LM50) by PCR. Sequencing analysis indicated that PtLFY was 2 629 bp long, composed of three exons and two introns and encoded 378 amino acids. The splice donor sites and the splice acceptor sites were in identical positions to the LFY and its homologues. The amino acid sequence inferred was 68%-99% homologous to those of LFY and its homologues by blast analysis in GenBank. The Southern blot analysis indicated that there was a single copy of the PtLFY gene in genomic DNA of male and female P. tomentosa (LM50 and 5082). The pBI121-Ptalfy (reverse)-intron-Ptlfy-GUS-nos was constructed using RNA interference (RNAi) technique and verified by PCR and digestion identification and transformed into tobacco. Some transgenic tobacco plants were obtained by PCR and PCR-Southern identification. The growth was generally repressed in transgenic tobacco plants compared with wild-type ones and some phenotypic differences were observed. [Supported by the National Natural Science Foundation of China (Grant No. 30371175) and Postdoctoral Foundation of China (Grant No. 2002032041)]     

Prokaryotic expression analysis of an NBS-type PtDRG01 gene isolated from Populus tomentosa Carr.

In order to investigate the protein features of an NBS gene (PtDRG01, EF157840) isolated from Populus tomentosa Carr., the full-length open reading frame was fused into a prokaryotic expression vector pGEX-KG. PCR analysis and double endonuclease digestion showed that the recombinant vector was successfully constructed and transferred into an expression host E. coli strain XA₉₀. It was indicated by SDS-PAGE analysis that IPTG treatment successfully induced the expression of a fusion protein of about 79 kD, which was consistent with the predicted value. In addition, the prokaryotic expression system was also optimized. The result suggests that 1 mmol/L IPTG treatment for 4 h at 37°C was most effective, and the product was predominately soluble and not extra-cellular secreting. Moreover, the fusion protein was purified with an affinity chromatography column using Glutathione Sepharose 4B. This work will lay a foundation for further studies on biological functions of the PtDRG01 gene. __________ Translated from Acta Botanica Boreali-Occidentalia Sinica, 2008, 28 (5): 0882–0888 [틫自: 컷놱횲컯톧놨]     

Variation of leaf characteristics in Populus tomentosa Carr.

An investigation was conducted to determine the extent of variations among nine provenances of Populus tomentosa Carr. in terms of leaf characteristics. A total of 263 accessions were studied under field conditions in the National Gene Bank of P. tomentosa in 2003. All of the accessions were characterized by 17 indices from 1 to 2-dimension constructions. Variance analysis of all characteristics showed that there were significant differences among the nine provenances and among individuals within each provenance. This study reveals that the evaluated germplasm appears to have a wide genetic base and high potential for further genetic improvements and it also indicates that abundant gene resources of P. tomentosa have been collected and preserved in the National Gene Bank. [Supported by the “Tenth Five-year Plan” National Key Project in Science and Technology (Grant No. 2002BA515B0303) and the National “863” Project (Grant No. 2002AA241071)]     

Improvement of wood properties by urea-formaldehyde resin and nano-SiO2

In order to improve wood properties of triploid clones of Populus tomentosa, urea-formaldehyde (UF) resin was compounded with nano-SiO₂, coupling agents and flame retardants in different ways to prepare five kinds of modifiers. The poplar wood samples were impregnated with the modifiers and heated to prepare UF-SiO₂-wood composites. The antiswelling efficiency, resistance of water absorption, oxygen index and hardness of the composites were measured. Results show that all of the modifiers reduced water absorption of poplar wood and enhanced flame resistance and hardness. Nano-SiO₂ showed a marked effect in improving the hardness of wood. In addition, all of the modifiers, except UF-C-SiO₂-polymer, improved the dimensional stability of poplar wood. The UF resin and nano-SiO₂ compound improved general properties of poplar wood. __________ Translated from Journal of Beijing Forestry University, 2006, 28(2): 123–128 [译自: 北京林业大学学报]     

Lignin characterization of triploid clones of Populus tomentosa Carr.

In order to understand the structural characteristics of lignin in triploid clones of Populus tomentosa and its changes in the processes of pulping and bleaching, milled wood lignin (MWL), lignin carbohydrate complex (LCC) and the residual lignin from kraft pulp (KP) and sulfite pulp (SP) were isolated and analyzed by Fourier transform infrared (FTIR) spectrum and ¹³C nuclear magnetic resonance (NMR). The most diagnostic peaks were assigned and the differences were discussed. The spectral patterns reveal that triploid P. tomentosa shows the specific features of hardwood from temperate areas, but in the spectrum of FTIR, the strength ratio of A 1270 cm⁻¹ to A1226 cm⁻¹ is 0.88, higher than the average of hardwood from temperate areas, which will make the lignin delignification more difficult during pulping and bleaching. The LCC from triploid P. tomentosa is mainly composed of xyloglucan and glucuronic acid, and other glucides have much lower ratio. In LCC FTIR, there are three peaks at 1 427, 1 329 and 1 046 cm⁻¹, indicating that both semi-cellulose and cellulose could exist in LCC, and that there might be relationships between cellulose and lignin. Compared with the residual lignin from KP and SP, the condensed structure in KP is more than that in SP.     

Effect of tree-crop intercropping on a young Populus tomentosa plantation

In order to study the effect of tree crop intercropping on a young plantation of Populus tomentosa in the plains along the Yellow River, field experiments were conducted by observing the growth of the plantation, the nutrient content in leaves, the nutrient and water content in the soil, and the output of crops. The relationship between forest growth and nutrient content in the tree leaves and the soil were analyzed. Results show that tree crop intercropping in young plantations can not only improve soil water content, but also enhance the contents of organic matter and the available nitrogen, phosphorus and potassium in soil resulting in the vigorous growth of the individual trees. Diameter at breast height (DBH) was positively related to the contents of organic matter in the soil, and the contents of N, P and K in the tree leaves had correlation coefficients of 0.967, 0.955, 0.988 and 0.972, respectively. Whole tree leaf area, crown width, number of branches and the mean length of branches in the intercropped plantation (intercropped with watermelon and vegetables, peanut and winter wheat, and soybean) were, respectively, 1.70–3.0 times, 2.22–2.47 times, 1.0–1.41 times and 1.70–2.32 times of those of CK (without intercropping). Diameter at breast height (DBH) and tree height in the intercropped plantation were 50.5%–136.7% and 27%–59.5% higher than those of the CK, respectively. The study also showed that intercropping with watermelon and vegetables proved to have the highest economic return among the treatments adopted. Tree crop intercropping in young plantations is an effective measure to increase forest growth and economic benefit. __________ Translated from Journal of Beijing Forestry University, 2006, 28(3): 81–85 [译自: 北京林业大学学报]     

Molecular cloning of a cellulose synthase gene PtoCesA1 from Populus tomentosa and its genetic transformation in tobacco

A 3 125 bp cellulose synthase gene, PtoCesA1, which has a 98% identity to PtrCesA1 from Populus tremuloides, was cloned from cDNA prepared from secondary xylem of P. tomentosa. Four anti-expression vectors with different fragments of PtoCesA1, named as pBIPF, pBICC1, pBIPR and pBIBR, were constructed. Some traits of transformed tobacco of pBICC1, pBIPR and pBIBR differed from wild types, such as small leaves, “dwarf” phenotype and thinner xylem and fiber cell walls than wild plants consistent with a loss of cellulose. It indicated that the growth of transgenic tobacco was restrained by the expression of anti-PtoCesA1. Transgenic tobacco was obtained and the contents of cellulose and lignin were analyzed as well as the width and length of fiber cells, and xylem thickness for both transgenic and control plants. Transformed tobacco showed a different phenotype from control plants and it implied that PtoCesA1 was essential for the cellulose biosynthesis in poplar stems. [Supported by the Hi-Tech Research and Development Program of China (863) (2001AA244060 and 2003AA244020) and National Basic Research Program of China (973) (J1999016003)]     

Duplication of locus coding of malate dehydrogenase in Populus tomentosa Carr.

Horizontal starch-gel electrophoresis was used to study crude enzyme extraction from young leaves of 234 clones of Populus tomentosa Carr. selected from nine provenances in North China. Ten enzyme systems were resolved. One hundred and fifty-six clones showing unusual allozyme band patterns at locus Mdh-1 were found. Three allozyme bands at locus Mdh-1 were 9:6:1 in concentration. Further studies on the electrophoretic patterns of ground mixed pollen extraction of 30 male clones selected at random from the 156 clones were conducted and it was found that allozyme bands at locus Mdh-1 were composed of two dark-stained bands and a weak band. Only one group of the malate dehydrogenase (MDH) zymogram composed of two bands was obtained from the electrophoretic segregation of pollen leachate of the same clones. A comparison of the electrophoretic patterns one another suggested that the locus Mdh-1 coding malate dehydrogenase in diploid species of P. tomentosa was duplicated. The duplicate gene locus possessed three same alleles and was located in mitochondria. The locus duplication of alleles coding malate dehydrogenase in P. tomentosa was discovered and reported for the first time. [Supported by the “Tenth Five-year Plan” National Key Project in Science and Technology (Grant No. 2002BA515B0303) and the National “863” Project (Grant No. 2002AA241071)]     

Cross breeding of Populus and its hybrids for cold resistance

Populus tomentosa was crossed with P. tremuloidis, P. grandidentata, P. alba × P. grandidentata and P. alba × Ulmus pumila in order to maintain its rapid growth and high wood quality and improve its resistance to cold. Two methods were used to increase the germination rate from 1.5% to 41.1% and the remaining rate from 1.7% to 44.2%. Forty crossing combinations were conducted and 2 744 hybrid seedlings were obtained. MX₄ × P. grandidentata (G-1-58), MX₃ × P. tremuloidis (T-44-60), MX₂ × P. tremuloidis (1-13-87-37) and MX₂ × (P. alba × P. grandidentata) were regarded as superior combinations after analysis and selection. Thirty seedlings of these combinations and 11 triploid seedlings identified by counting their chromosomes were selected as super plants. [Supported by the Doctoral Foundation of Ministry of Education (Grant No. 200220022004) and the National “863” Project (Grant No. 2002AA241071)]     

基于cpDNA rps16序列分析兰考泡桐与白花泡桐和毛泡桐的遗传关系

【目的】通过测序法分析兰考泡桐与白花泡桐和毛泡桐在叶绿体rps16序列上的遗传差异,旨在分析三者之间在叶绿体基因上的变化特点和规律,探讨其种间的遗传关系。【方法】选取兰考泡桐、白花泡桐和毛泡桐各15个样本,对其提取的DNA用PCR扩增获得特异片段,并将其纯化与测序。利用软件Clustal X 2.0对所得序列进行排序;运行MEGA 4软件,进行多序列比对,分析其序列特征,并计算出K2P遗传距离。【结果】(1)对获得的rps16序列进行测定分析,得兰考泡桐序列长度分别为932 933 bp;白花泡桐序列长度为932 bp;毛泡桐序列长度分别为916918 bp。对所得rps16序列进行排序后的长度为938 bp,平均GC含量为34.31%。3个种所代表的个体之间共有10个变异位点,占整个序列长度的1.07%。其中有9个变异位点属于碱基插入或缺失类型,占变异位点总数的90%,占整个序列长度的0.96%。有1个变异位点属于碱基替换类型,占整个变异位点总数的10%,占整个序列长度的0.11%。(2)整个rps16片段的序列共有10个变异位点,其中兰考泡桐与白花泡桐在总的变异位点上,具有一致的碱基位点9个,占总变异的90%。而兰考泡桐与毛泡桐相比,没有相同的碱基。【结论】根据三种泡桐的rps16序列的序列特征和变异位点的分析,表明在叶绿体遗传方面,兰考泡桐具有与白花泡桐更多相似的遗传物质,其亲缘关系较近。综上所述,推测兰考泡桐与白花泡桐可能来自同一母系遗传。     

Successful <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation of <Emphasis Type="Italic">Populus tomentosa</Emphasis> with apple <Emphasis Type="Italic">SPDS</Emphasis> gene

The problem of salinized soils has become one of the most serious constraints to agricultural and forest productivity. With the purpose of enhancing salt stress tolerance of Populus tomentosa, we transformed this tree species with spermidine synthase （SPDS） genes derived from an apple by an Agrobacterium-mediated method. Four transgenic clones were confu＇med by PCR and Southern blot analysis. As well, the expression of introduced SPDS genes was analyzed by real-time quantitative PCR.     

Evaluation of the sap flow using heat pulse method to determine transpiration of the Populus euphratica canopy

The sap flow of the sampled Populus euphratica stems at different radial depths and directions had been studied in Ejina Oasis, in the lower reaches of the Heihe River. Based on sap flow measurements, the transpiration of the entire canopy was calculated. Results showed a linear correlation between the sap flow and the sapwood area of the P. euphratica. Through the analysis of the diameter at breast height in the sample plot, it was found that the distribution of the diameters and the corresponding sapwood area was exponentially correlated, with the coefficient of correlation being 0.976,7. The calculated transpiration of the Populus euphratica canopy was 214.9 mm based on the specific conductivity method. Translated from Scientia Silvae Sinicae, 2006, 42(7): 28–32 [译自: 林业科学]     

Growth analysis of the competition–density effect in non-self-thinning Populus deltoides and Populus?×?euramericana plantations

The competition–density (C–D) effect for non-self-thinning Populus deltoides and Populus × euramericana plantations from 3 to 9 years was analyzed using the reciprocal equation of the C–D effect. The C–D effect was well described by the reciprocal equation, and with the progress of time the C–D curve, on logarithmic coordinates, of the P. × euramericana plantations shifted upward faster than that of the P. deltoides plantations. With increasing physical time t, the biological time τ, i.e. the integral from zero to t of the coefficient of growth λ(t) in the general logistic curve with respect to t, increased rapidly during early growth stages and the increases in τ gradually became slow during later growth stages. This trend was more evident in the P. deltoides plantations than in the P. × euramericana plantations. The coefficients A and B included in the reciprocal equation were calculated at each growth stage. With increasing τ, the coefficient A, the reciprocal of which means the asymptote of yield (=wρ) at a given growth stage, increased abruptly to a maximum value and then tended to decrease gradually to a constant level. On the other hand, the coefficient B, the reciprocal of which means the asymptote of mean stem volume at a given growth stage, decreased exponentially and tended to be close to zero with increasing τ. The λ(t) decreased with increasing stand age, whereas the final yield Y(t) defined as W(t) ρ, where W(t) is the asymptote of w in the general logistic growth curve, increased gradually with increasing stand age. The differences in coefficients A, B, and λ(t) between the two species were reported.     

寄生小蜂对小青×黑杨树皮及杨圆蚧挥发油的行为反应

Four-armed airflow olfactometer was used to determining the foraging behavior ofPteroptrix longgiclava (Girault) (Hymenoptera: Aphelinidae) andEncarsia gigas (Tshumakova) (Hymenoptera: Aphelinidae) to the essential oils which emitted from the healthy bark ofPopulus pseudo-simonii×P. nigra, the infested bark injured byQuadraspidiotus gigas (Thiem & Gerneck), the body and scale of fixed 1st-instar-nymph ofQ. gigas. The results from these experiments showed that the volatile oils produced from the injured bark and from the scale of fixed 1st-instar-nymph had a higher attractive ability to female adults of the two species of wasps. The essential oil produced from the scale of the pest at dosages of 3–7 μL and the essential oil emitted by injured bark at dosages of 5–9 μL had a stronger alluring effect on the host searching behavior ofPteroptrix longgiclava. The essential oil from the body of fixed 1st-instar-nymph ofQ. gigas also had certain effect on the host locating effort ofPteroptrix longgiclava andEncarsia gigas. Those two wasps did not shown any reaction to the essential oil produced by the healthy bark of poplar. Foundation item: This paper was supported by National Natural Science Foundation of China (39970620) and the “TRAPOYT” Biography: CHI De-fu (1962-), male, Ph.D., Professor in Northeast Forestry University, Harbin 150040, P.R. China Responsible editor: Chai Ruihai     

Plant growth, biomass production and nutrient accumulation by slash/mulch agroforestry systems in tropical hillsides of Colombia

Planted fallow systems under ‘slash and mulch’ management were compared with natural fallow systems at two farms (BM1 and BM2) in the Colombian Andes. The BM1 site was relatively more fertile than the BM2 site. Planted fallow systems evaluated included Calliandra calothyrsus CIAT 20400 (CAL), Indigofera constricta (IND) or Tithonia diversifola (TTH). During each pruning event slashed biomass was weighed, surface-applied to the soil on the same plot and sub-samples taken for chemical analyses. While Indigofera trees consistently showed significantly greater (p < 0.05) plant height and collar diameter than Calliandra trees at both study sites, only collar diameter in Indigofera was significantly affected at all sampling times by differences between BM1 and BM2. After 27 months, TTH presented the greatest cumulative dry weight biomass (37 t ha^–1) and nutrient accumulation in biomass (417.5 kg N ha^–1, 85.3 kg P ha^–1, 928 kg K ha^–1, 299 kg Ca ha^–1 and 127.6 kg Mg ha^–1) among planted fallow systems studied at BM1. Leaf biomass was significantly greater (P < 0.05) for CAL than IND irrespective of site. However, CAL and IND biomass from other plant parts studied and nutrient accumulation were generally similar at BM1 and BM2. At both sites, NAT consistently presented the lowest biomass production and nutrient accumulation among fallow systems. Planted fallows using Calliandra and Indigofera trees had the additional benefit of producing considerable quantities of firewood for household use. This revised version was published online in June 2006 with corrections to the Cover Date.     

Root biomass and underground C and N storage of the primitive Korean pine and broad-leaved forest and its different succession stages in Changbai Mountain, northeast China

This paper studied root biomass and underground carbon (C) and nitrogen (N) storage of a more than 200-year-old primitive Korean pine and broad-leaved forest and its two 20-and 80-year-old secondary Populus davidiana and Betula platyphylla forests in Changbai Mountain, northeast China. The results showed that with forest succession, the root biomass of 20-year-old, 80-year-old, and primitive forests was 2.437, 2.742, and 4.114 kg/m², respectively. The root C storage was 1.113, 1.323, and 2.023 kg/m², soil C storage was 11.911, 11.943, and 12.587 kg/m², and underground C storage was 13.024, 13.266, and 14.610 kg/m², respectively, while the root N storage was 0.035, 0.032, and 0.038 kg/m², soil N storage was 1.208, 1.222, and 0.915 kg/m², and underground N storage was 1.243, 1.254, and 0.955 kg/m², respectively, which indicated that along with forest succession, the forest underground became a potential “carbon sink,” whereas underground N storage did not change obviously. __________ Translated from Chinese Journal of Applied Ecology, 2005, 16(7): 1,195–1,199 [译自: 应用生态学报, 2005, 16(7): 1,195–1,199]