Characterization of phytoplasmas detected in Chinaberry trees with symptoms of leaf yellowing and decline in Bolivia

Polymerase chain reaction (PCR) assays were used to detect phytoplasmas in foliage samples from Chinaberry ( Melia azedarach ) trees displaying symptoms of yellowing, little leaf and dieback in Bolivia. A ribosomal coding nuclear DNA (rDNA) product (1·8 kb) was amplified from one or more samples from seven of 17 affected trees by PCR employing phytoplasma-universal rRNA primer pair P1/P7. When P1/P7 products were reamplified using nested rRNA primer pair R16F2n/R16R2, phytoplasmas were detected in at least one sample from 13 of 17 trees with symptoms. Restriction fragment length polymorphism (RFLP) analysis of P1/P7 products indicated that trees CbY1 and CbY17 harboured Mexican periwinkle virescence (16SrXIII)-group and X-disease (16SrIII)-group phytoplasmas, respectively. Identification of two different phytoplasma types was supported by reamplification of P1/P7 products by nested PCR employing X-disease-group-specific rRNA primer pair R16mF2/WXint or stolbur-group-related primer pair fSTOL/rSTOL. These assays selectively amplified rDNA products of 1656 and 579 bp from nine and five trees with symptoms, respectively, of which two trees were coinfected with both phytoplasma types. Phylogenetic analysis of 16S rDNA sequences revealed Chinaberry yellows phytoplasma strain CbY17 to be most similar to the chayote witches'-broom (ChWBIII-Ch10) agent, a previously classified 16SrIII-J subgroup phytoplasma. Strain CbY1 resembled the Mexican periwinkle virescence phytoplasma, a 16SrXIII-group member. The latter strain varied from all known phytoplasmas composing group 16SrXIII. On this basis, strain CbY1 was assigned to a new subgroup, 16SrXIII-C.     

Relative susceptibility of four species of African mahogany to the shoot borer Hypsipyla robusta (Lepidoptera: Pyralidae) in the moist semideciduous forest of Ghana

We examined the relative susceptibility of four mahogany species, Khaya ivorensis, Khaya anthotheca, Entandrophragma angolense, and E. utile, to Hypsipyla robusta attack. Seeds were obtained from one to three parent trees for each species. The research was conducted in the moist semideciduous forest zone in Ghana and used a randomized complete block design. Tree height and diameter and height to first branch were measured until 24 months after out-planting in the field. H. robusta damage was assessed by counting the numbers of shoots attacked, branches, and dead shoots. Khaya spp. grew better but experienced more attack than Entandrophragma spp. The relative susceptibility to H. robusta attack, from most to least, of the four species was: K. anthotheca > K. ivorensis > E. angolense > E. utile. At 24 months, the mean number of shoots attacked per tree ranged from 1.0 for an E. utile seed source to 3.6 on for a K. anthotheca seed source. At 15 months, K. anthotheca and K. ivorensis started branching at about 1.5 m, but height of clear trunk increased over time due to self-pruning. As K. anthotheca grew taller, the number of H. robusta attacks per tree declined. This suggested that selection of genotypes and species that are tolerant of H. robusta attack based on infestation of young plants may not be appropriate. Genetic factors more completely reflecting the response of different species and genotypes to H. robusta attack may manifest themselves at later growth stages.     

Antifeedant activity of fruit and seed extracts ofMelia azedarach andazadirachta indica on larvae ofSesamia nonagrioides

Methanolic extracts of seeds and fruits of the chinaberry tree,Melia azedarach L. (Meliaceae), showed strong antifeedant activity against 2nd instar larvae ofSesamia nonagrioides Lefèbvre (Lepidoptera: Noctuidae), a very serious pest of maize(Zea mays L.) in Mediterranean countries. Extracts were applied in an artificial diet at concentrations of 1000 and 2000 ppm. The parameters used to evaluate the activity were larval growth rates; quantity of food ingested; phagodepression/phagostimulation index; quantity of frass produced; quantity of material ingested; duration of larval development; and cumulative mortality. Seed extract showed high bioactivity at both doses, while fruit extract proved to be less active, and only at the higher dose used (2000 ppm) did it display a slight antifeedant activity. The activity of theM. azedarach seed extract at the higher dose (2000 ppm) was comparable to that of pure azadirachtin applied at a dose of 1.25 ppm, or to ‘Mubel’, a commercial extract ofAzadirachta indica A. Juss. (Meliaceae), applied at a dose of 75 ppm.     

Cytotoxic nor-dammarane triterpenoids from Dysoxylum hainanense

Four new nor-dammarane triterpenoids, 12β-O-acetyl-15α,28-dihydoxy-17β-methoxy-3-oxo-20,21,22-23,24,25,26,27-octanordammanran (1), 12β-O-acetyl-15α,17β,28-trihydoxy-3-oxo-20,21,22-23,24,25,26,27-octanordammanran (2), 12β-O-acetyl-15α,28-dihydoxy-3-oxo-17-en-20,21,22-23,24,25,26,27-octanordammanran (3), and 12β,15α,17β,28-tetrahydoxy-3-oxo-20,21,22-23,24,25,26,27-octanordammanran (4), were isolated from the 70% EtOH extract of Dysoxylum hainanense. The structures of the new compounds were elucidated by spectral methods. All the triterpenoids were in vitro evaluated for their cytotoxic activities against four tumor cell lines (A549, SK-OV-3, SKMEL-2 and HCT15).     

Triterpenes and steroids from the leaves of Aglaia exima (Meliaceae)

A study on the leaves of Aglaia exima led to the isolation of one new and seven known compounds: six triterpenoids and two steroids. Their structures were elucidated and analyzed mainly by using spectroscopic methods; 1D and 2D NMR, mass spectrometry, UV spectrometry and X-ray. All the triterpenoids and steroids were measured in vitro for their cytotoxic activities against eight cancer cell lines; lung (A549), prostate (DU-145), skin (SK-MEL-5), pancreatic (BxPC-3), liver (Hep G2), colon (HT-29), breast (MCF-7) and (MDA-MB-231). The new cycloartane triterpenoid, 24(E)-cycloart-24-ene-26-ol-3-one 1, showed potent cytotoxic activity against colon (HT-29) cancer cell line (IC₅₀ 11.5 μM).     

Antifungal activity of limonoids from Khaya ivorensis

Chemical investigation of the diethyl ether extract of the stem bark of Khaya ivorensis A Chev (Meliaceae) afforded ten limonoids of angolensates, ring D-opened limonoids and mexicanolides. The structures of the limonoids isolated were determined by comparison of their (1)H and (13)C NMR data with those reported in the literature. These compounds were evaluated for their antifungal activity against the plant pathogenic fungus Botrytis cinerea Pers. Methyl 6-hydroxyangolensate and 3,7-dideacetylkhivorin were also tested for their antifungal and antibacterial activities on several fungal and bacterial species. Methyl angolensate and 1,3,7-trideacetylkhivorin displayed the highest antifungal activity against B. cinerea, with respectively 62.8 and 64.0% mycelial growth inhibition at 1000 mg litre(-1), and 73.3 and 68.6% mycelial growth inhibition at 1500 mg litre(-1). 3,7-Dideacetylkhivorin showed stronger antifungal and antibacterial activities than methyl 6-hydroxyangolensate against all of the test fungi and bacteria except Penicillium expansum Link. This is the first report on the antifungal and antibacterial effects of these limonoids. Structure-antifungal activity relationships of the limonoids isolated are discussed.     

Poor regulatory capacity limits the ability of science to influence the management of mahogany

Decades of research have had virtually no impact on harvesting rates or harvesting practices for mahogany (Swietenia spp.), among the most valuable timber species of Latin America. Despite the existence of science-based regulations, mahogany is rapidly and often illegally harvested to the point where its density is so depleted that logging is no longer commercially viable. The lack of influence of science on forest management is not a result of scientific deficiency; rather, it is a political and economic failure to implement existing forest management policies. Until political will and regulatory capacity for enforcement exist or until buyers insist on meaningful verification that shipments were legally obtained, there is little incentive for reform and policies regulating the use of mahogany will not be implemented. Thus, under present conditions, there is little opportunity for science to influence the fate of mahogany. The case study of mahogany provides an excellent example not only of the difficulty for research to inform forest management, but also of demonstrating the key elements necessary for effective implementation of any forest policy.     

Insecticidal activity of crude seed extracts of<Emphasis Type="Italic">Annona</Emphasis> spp.,<Emphasis Type="Italic">Lansium domesticum</Emphasis> and<Emphasis Type="Italic">Sandoricum koetjape</Emphasis> against lepidopteran larvae

Crude ethanolic seed extracts ofAnnona muricata, A. squamosa (Annonaceae),Lansium domesticum andSandoricum koetjape (Meliaceae) collected from different locations and years in Maluku, Indonesia, were screened for inhibition of larval growth against the polyphagous lepidopteranSpodoptera litura (Noctuidae). Extracts ofA. squamosa were significantly more active (20-fold) than those ofA. muricata. A. squamosa collected from Namlea yielded the extracts with the greatest inhibitory activity. There were significant differences among locations for bothA. squamosa andA. muricata but not forL. domesticum andS. koetjape. Extracts ofA. squamosa, collected from Namlea, inhibited larval growth in a dose-dependent manner, with a dietary EC₅₀ (effective concentration to inhibit growth by 50% relative to controls) of 191.7 ppm fresh weight. Extracts ofA. squamosa collected from individual trees in Namlea also varied in growth inhibitory effect againstS. litura andTrichoplusia ni larvae. This species is a candidate for development of a botanical insecticide for local use in Indonesia. http://www.phytoparasitica.org posting Dec. 1, 2003.     

苦楝内生真菌的初步分离和筛选

从苦楝（Meliaazedarach L．）的根、茎、叶、果实中分离得到99株14个属的内生真菌（33株因不产孢子未鉴定）。其中7月分离得到7个属，10月得到14个属的内生真菌。由分离结果可知，根、茎中内生真菌的属多于叶和果实，且曲霉属的灰绿曲霉组、链格孢属和未见孢子Ⅰ在全株均有分布。对各菌株次生代谢物进行检测，可知O-L-5、O-SCⅡ-4和O-RC-3能产生较多的苦楝素，为目的菌株。     

割舌树属植物的化学成分及生物活性研究进展

对割舌树属植物化学成分及生物活性进行了综述。研究表明,从割舌树属中共分离得到47个化合物,包括三萜、酚类和甾体等结构类型。一些三萜和酚类单体成分显示了较好的细胞保护、抗氧化和抗疟疾活性。