哀牢山湿性常绿阔叶林及不同类型次生植被的幼苗更新特征

采用"空间代替时间"的方法,对云南哀牢山徐家坝地区湿性常绿阔叶林及不同类型次生植被中木本植物幼苗的种类组成、数量及更新方式等进行了调查.结果表明:在所有调查样地中,共记录到木本植物幼苗46种,其中乔木31种、灌木15种.荒草地、滇山杨林、栎类萌生林、原生林4种不同植被类型的幼苗密度分别是(421.9±59.5)、(34.4±8.1)、(31.6±7.2)、(18.5±6.6)株·25 m-2.随着演替的进行,灌木的比例逐渐减小,乔木的比例则逐渐增加.在森林恢复演替过程中,处于演替初期的荒草地灌木萌生更新占优势,到了演替后期则以乔木萌生幼苗更新为主.随着群落演替进程的增加,幼苗密度逐渐减少,幼苗生活型和木本植物的幼苗更新方式均发生变化.     

外源一氧化氮对镉胁迫下黄瓜幼苗生长、活性氧代谢和光合特性的影响

镉是植物生长的非必需元素,它具有很大的生物毒性,与其它重金属相比,更易被植物吸收积累。通过采用营养液水培试验的方法,研究了外源一氧化氮（Nitric oxide,NO）对不同浓度Cd^2＋（100μmol L^-1．300μmol L^-1,500μmol L^-1）胁迫下黄瓜幼苗生长、叶片光合特性以及活性氧代谢的影响。结果表明：300μmol L^-1NO供体硝普钠（Sodium nitrop russide,SNP）能显著缓解镉胁迫时黄瓜植株造成的伤害,对300μmol L^-1 Cd^2＋处理的黄瓜幼苗缓解效果最好,可提高幼苗的生长量,增强幼苗叶片超氧物歧化酶（SOD）、过氧化物酶（POD）活性;提高了叶片叶绿素和脯氨酸（Pro）含量;降低了叶片内二醛（MDA）含量。     

威胁棉花生产的外来入侵新害虫——扶桑绵粉蚧

2008年8月,在广东省广州市发现一种严重危害扶桑的害虫,经鉴定确认为扶桑绵粉蚧Phenacoccus solenopsis Tinsley。2008年12月16日调查发现,在广州市的扶桑上多点发生。扶桑绵粉蚧原产美洲,最近几年入侵印度和巴基斯坦,严重危害棉花,其暴发危害已经造成了重大损失,成为威胁世界棉花安全的重大入侵害虫。文章提供扶桑绵粉蚧的形态特征、寄主、分布、危害等情况,并对其检疫与防控措施等提出建议。     

SNP处理的辣椒幼苗对Cd^2＋胁迫的生理响应

采用溶液培养方法研究外源NO供体硝普钠（SNP）对Cd^2＋胁迫下辣椒幼苗生长和生理特性影响的结果表明：75μmol·L^-1SNP能在一定程度上缓解较高浓度Cd^2＋对辣椒幼苗生长、叶中Chla和Chlb含量以及根系活性的抑制作用,降低丙二醛（MDA）含量,增强超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、过氧化物酶（POD）的活性。     

Isolation and characterization of farnesyl diphosphate synthase from the cotton boll weevil,Anthonomus grandis

Farnesyl diphosphate synthase (FPPS) catalyzes the consecutive condensation of two molecules of isopentenyl diphosphate with dimethylallyl diphosphate to form farnesyl diphosphate (FPP). In insects, FPP is used for the synthesis of ubiquinones, dolicols, protein prenyl groups, and juvenile hormone. A full‐length cDNA of FPPS was cloned from the cotton boll weevil, Anthonomus grandis (AgFPPS). AgFPPS cDNA consists of 1,835 nucleotides and encodes a protein of 438 amino acids. The deduced amino acid sequence has high similarity to previously isolated insect FPPSs and other known FPPSs. Recombinant AgFPPS expressed in E. coli converted labeled isopentenyl diphosphate in the presence of dimethylallyl diphosphate to FPP. Southern blot analysis indicated the presence of a single copy gene. Using molecular modeling, the three‐dimensional structure of coleopteran FPPS was determined and compared to the X‐ray crystal structure of avian FPPS. The α‐helical fold is conserved in AgFPPS and the size of the active site cavity is consistent with the enzyme being a FPPS. © 2009 Wiley Periodicals, Inc.     

Influence of tannic acid and Cry1Ac toxin of Bacillus thuringiensis on larval survival, growth, and development of Helicoverpa armigera

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) causes huge economic losses in cotton production around the world. Tannin, one of the important secondary substances in cotton plants, can increase the δ‐endotoxin activity of Bacillus thuringiensis ssp. kurstaki. The mechanism of interaction between tannin and Bt toxin on H. armigera is unclear. We investigated the interaction between tannic acid and Cry1Ac toxin in H. armigera, and monitored survival, growth, and development during the larval period after treating the larvae with four concentrations of Cry1Ac toxin (0, 2, 8, and 14 μg^?1) alone or in combination with four concentrations of tannic acid (0, 0.5, 1, and 2 mg g^?1). Mortality of larvae treated with both tannic acid and Cry1Ac was higher than the mortality of larvae treated with tannic acid or Cry1Ac alone. Mortality was 47.5 and 51.5% in larvae treated with 14 μg g^?1 Cry1Ac alone or 2 mg g^?1 tannic acid alone, respectively. In contrast, larval mortality was 75% when treated with the mixture of 14 μg g^?1 Cry1Ac and 2 mg g^?1 tannic acid, suggesting that a mixture of the two enhanced the effectiveness of each one alone. The developmental time of larvae treated with the combination of tannic acid and Cry1Ac was significantly longer than when they were treated with Cry1Ac or tannic acid alone. Larval weight, pupal weight, and pupation rate were also significantly reduced in larvae treated with both toxins, compared with the larvae treated with either toxin alone. These results showed that the interactive effect of tannic acid and Cry1Ac on larval growth inhibition is additive, and that tannic acid improves Cry1Ac toxicity to insects. Tannic acid used in combination with B. thuringiensis might potentially reduce overall insecticide use, thus delaying development of insecticide resistance.     

Susceptibility of Tree Seedlings to Biotic and Abiotic Hazards in the Understory of a Moist Tropical Forest in Panama

We evaluated temporal patterns of seedling survival of eight Neotropical tree species generated under multiple abiotic and biotic hazards (vertebrates, disease, litterfall) in the forest understory on Barro Colorado Island, Panama. Seedlings were transplanted at first leaf expansion in low densities along a 6-km transect and damage and mortality were recorded for 1 yr. We also planted and monitored small and large artificial seedlings to estimate physical disturbance regimes. During 0–2 mo after transplant, vertebrate consumers of reserve cotyledons caused high mortality of real seedlings, but little damage to artificial seedlings. On real seedlings after 2 mo, disease became an important agent of mortality, despite a decrease in overall mortality rates. Damage by litterfall remained relatively low during the 1-yr study period. Survival ranks among species showed ontogenetic shifts over time, as species changed susceptibility to the mortality agents. Survival after 2 mo was positively correlated with stem toughness, not because species with tough stems were less likely to receive mechanical damage, but because they survived better after receiving mechanical damage. Within each transplant station, artificial seedlings were not good predictors of litterfall damage experienced by real seedlings. Forest-wide litterfall damage level, however, was similar for both real and artificial seedlings ( ca 10%/yr), a moderate level compared to other tropical forests. In conclusion, species traits including biomechanical traits interact to create complex temporal patterns of first year seedling survival, resulting in ontogenetic shifts that largely reflect changes in the relative importance of vertebrate consumers relative to other hazards.     

<Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated co-transformation of multiple genes in upland cotton

Two cotton genotypes, Simian 3 (SM 3) and WC, were co-transformed using a mixture of four Agrobacterium tumefaciens cultures of strain LBA4404, each carrying a plasmid harboring the following genes, Bt + sck (for Bacillus thuringenesis protein and modified Cowpea trypsin inhibitor), bar (for glufosinate), keratin, and fibroin. The frequency of callus induction, embryogenesis, and plant regeneration were notably different between the two genotypes. However, there were no differences between the two genotypes for number of plantlets carrying multiple gene copies of different gene combinations as well as transformation frequency for different gene combinations. PCR analysis indicated that more than 80% of plantlets carried the nptII gene for kanamycin resistance. Overall, the co-transformation frequency of two or more genes was about 35%. Southern blot analysis confirmed integration of target genes into the cotton genome, and the number of copies of the transgene(s) varied from one to four. Multiple transgene expression was confirmed by RT-PCR analysis in some transgenic lines. Further analysis of T₁ plants demonstrated that multiple transgenes were inherited and expressed in progenies. Fei-Fei Li and Shen-Jie Wu are joint first authors.     

Functions of canopy-stored seeds in the dune ecosystem: conclusions from Agriophyllum squarrosum and Artemisia wudanica

Delay in seed release is found in the dune ecosystem. However, its functions have been rarely reported. We studied delayed seed release in the Agrio-phyllum squarrosum (Chenopodiaceae), an annual psam-mophyte, and the Artemisia wudanica (Asteraceae), a psammophilous subshrub in an active sand dune field in Inner Mongolia, China, to get insights into its functions in dealing with sand movement. We concluded that delay in seed release in the dune ecosystem are as follows: (1) postponing dispersal of a portion of seeds until the end of windy season and the start of growing season; (2) regulating the spatiotemporal pattern of seed bank; (3) helping psammophytes adapt to wind erosion on the active sand dune; and (4) helping psammophytes realize long-distance dispersal.     

Advances in research of induced resistance to insects in cotton

Any change in a plant that occurs following herbivory or environmental factors is an induced response. These changes include phytochemical induction, increases in physical defenses, emission of volatiles that attract predators and parasitoids of herbivores, and reduction in plant nutritional quality for herbivores, which is termed induced resistance. Induced resistance has been demon-strated ubiquitously in plants. It is one of our goals to review what is known about the induced resistance to herbivorous insects in cotton, including three resistance secondary metabolites (terpenoid, tannin, and flavonoids) that are contained at any significant levels of resistance to herbivorous insects in cotton cultivates. In many cases, the quantities or quality of secondary metabolites in plant are changed after attacked by insects. This review focuses on induced plant resistance as quantitative or qualitative enhancement of defense mechanism against insect pests, especially on the abiotic-elicitors-induced resistance in cotton plants. The abiotic-elicitor of cupric chloride, an exogenous inorganic compound, may induce the second-ary metabolites accumulation and is referred to as a copper-inducible elicitor (CIE). Finally, we discuss how copper-inducible elicitor may be used in the Integrated Pest Management (IPM) system for cotton resistance control.