Biosynthesis of sesquiterpenes in Hymenaea inferred from their quantitative co-occurrence

Leaf pocket resins of 11 species of the tropical arborescent genus Hymenaea are virtually identical qualitatively, but of widely varying quantitative proportions. Within this large range of variability, several strong positive quantitative correlations between resin constituents were found, especially between caryophyllene and β-humulene and between γ-muurolene and δ-cadinene. These data lead to clarification of sesquiterpene biosynthetic routes in Hymenaea. In addition, quantitative relationships found among caryophyllene, α- and β-selinene, γ-muurolene and δ-cadinene are explained only with difficulty by long accepted biosynthetic pathways, and the intermediacy of germacrenes is suggested.     

Effect of papaya (Carica papaya) leaf extract as dietary growth promoter supplement in red hybrid tilapia (Oreochromis mossambicus × Oreochromis niloticus) diet

The purpose of this experiment was to examine the potential use of Carica papaya leaf extract as a supplement to promote growth and improve feed utilization in red hybrid tilapia. Five diets were formulated containing isolipidic (80 g/kg) and isonitrogenic (350 g/kg) levels. All feeds contained similar types and amounts of raw materials but differed in the inclusion of papaya leaf extract (0, 5, 10, 20 and 40 g/kg feed). The initial size of fish used was 2.3 ± 0.01 g. Each diet was performed in triplicate tanks, and the feeding period was 12 weeks. Fish fed diet containing 2% papaya leaf extract (PLE) had the highest final weight, 31.14 ± 1.47 g, followed by 1% PLE (27.27 ± 1.75 g). These two diets (1% and 2%) were also showed significant improvements of weight gain, SGR, and feed efficiency of the red hybrid tilapia (p < 0.05). However, papaya leaf extract did not affect the HSI, VSI, PER, digestive enzymes activity, blood composition, and survival rate. Supplementing the diets with papaya leaf extract lowered serum urea. Findings of this research suggest that adding papaya leaf extract to the diet of red hybrid tilapia improves growth and feed efficiency without adversely affecting blood parameters. Therefore, an inclusion level between 1% and 2% of the papaya leaf extract is recommended as a feed additive to promote red hybrid tilapia fry growth.     

Leafminers help us understand leaf hydraulic design

Leaf hydraulics of Aesculus hippocastanum L. were measured over the growing season and during extensive leaf mining by the larvae of an invasive moth (Cameraria ohridella Deschka et Dimic) that specifically destroy the palisade tissue. Leaves showed seasonal changes in hydraulic resistance (R_lamina) which were related to ontogeny. After leaf expansion was complete, the hydraulic resistance of leaves and the partitioning of resistances between vascular and extra‐vascular compartments remained unchanged despite extensive disruption of the palisade by leafminers (up to 50%). This finding suggests that water flow from the petiole to the evaporation sites might not directly involve the palisade cells. The analysis of the temperature dependence of R_lamina in terms of Q₁₀ revealed that at least one transmembrane step was involved in water transport outside the leaf vasculature. Anatomical analysis suggested that this symplastic step may be located at the bundle sheath where the apoplast is interrupted by hydrophobic thickening of cell walls. Our findings offer some support to the view of a compartmentalization of leaves into well‐organized water pools so that the transpiration stream would involve veins, bundle sheath and spongy parenchyma, while the palisade tissue would be largely by‐passed with the possible advantage of protecting cells from short‐term fluctuations in water status.     

A comparison of direct and indirect methods for measuring leaf and surface areas of individual bushes

Indirect estimates of leaf area from measurements with three commercially available instruments (DEMON, LAI-2000 and Sunfleck Ceptometer) were compared with directly measured areas of individual Retama sphaerocarpa bushes. The three indirect methods gave good estimates of the total surface area of individual bushes. For the DEMON, the method of log-linear averaging of transmitted radiation gave estimates closer to directly measured surface area than the method of averaging transmission linearly. For the LAI-2000, estimated surface area index multiplied by canopy projected area gave the best agreement with directly measured values. For measurements with the Sunfleck Ceptometer, values of surface area estimated from the transmission of photosynthetic quantum flux density, without correcting for diffuse radiation, gave the best agreement with directly measured values. Surface areas estimated by the three instruments were not significantly different from directly measured total (leaf + branch + stem) surface areas. Leaf surface area could be calculated from estimated total surface area minus directly measured branch surface area. Measured branch surface area was linearly related to canopy projected area.     

Leaf traits of natural populations of <Emphasis Type="Italic">Adiantum reniforme</Emphasis> var. <Emphasis Type="Italic">sinensis</Emphasis>, endemic to the Three Gorges region in China

Leaf mass per unit area (LMA), carbon and nitrogen contents, leaf construction cost, and photosynthetic capacity (P _max) of Adiantum reniforme var. sinensis, an endangered fern endemic to the Three Gorges region in southwest China, were compared in five populations differing in habitat such as soil moisture and irradiance. The low soil moisture and high irradiance habitat population exhibited significantly higher LMA, area-based leaf construction (CC_A), and carbon content (C_A), but lower leaf nitrogen content per unit dry mass (N_M) than the other habitat populations. The high soil moisture and low irradiance habitat populations had the lowest CC_A, but their cost/benefic ratios of CCA/P _max were similar to the medium soil moisture and irradiance habitat population due to their lower leaf P _max. Hence A. reniforme var. sinensis prefers partially shaded, moist but well-drained, slope habitats. Due to human activities, however, its main habitats now are cliffs or steeply sloped bare rocks with poor and thin soil. The relatively high energy requirements and low photosynthetic capacity in these habitats could limit the capability of the species in extending population or interspecific competition and hence increase its endangerment.     

烟粉虱携带番茄黄化曲叶病毒检测及其传入山东省的考证

【背景】番茄黄化曲叶病毒（TYLCV）是由媒介昆虫烟粉虱传播的一种双生病毒,对蔬菜及烟草等经济作物造成严重危害。前人资料表明,该病毒于2006年传人我国南方地区,2007年传人山东省,2008年后在山东各地逐渐蔓延扩散。【方法】为了考证TYLcV传人山东省的时间,本研究利用mtCOI基因对于2005和2006年7—8月份在山东省不同地区作物上共采集的15份烟粉虱样品进行了生物型鉴定,并进一步检测了烟粉虱携带TYLCV情况,同时对PCR扩增产物进行了测序分析。【结果】2005年的4份样品烟粉虱生物型均为B型,均不携带TYLCV。2006年的11份烟粉虱样品为B型与Q型混合样品,其中,2份烟粉虱样品检测到TYLCV,进一步证实该病毒为TYLCV。【结论与意义】本研究首次证实了TYLCV早在2006年就已经传入山东省。研究结果不仅对于防控该病毒具有重要指导意义,而且对于其入侵生物学研究也具有重要参考价值。     

The Association of Phytoplasma with Stunting, Leaf Necrosis and Witches' Broom Symptoms in Magnolia Plants

In 1999–2000 a severe disease was observed on plants of four Magnolia spp. cultivated in a commercial nursery in Poland. Affected plants showed a progressive loss of vigour, were stunted, and had severely malformed leaves, leaf necrosis and witches' broom. Phytoplasma was detected in magnolias with severe symptoms and in dodder-inoculated Catharanthus roseus seedlings by nested polymerase chain reaction (PCR) assay with primer pair R16F1/R0 followed by universal (rA/fA) and group specific (R16(I)F1/R1) primer pairs which amplified a fragment of phytoplasma 16S rDNA. The PCR products (560 bp or 1.1 kb) of all samples used for restriction fragment length polymorphism analysis after digestion with endonuclease enzymes Alu I and Mse I produced the same profile which corresponded to that of an aster yellows phytoplasma reference strain. Phytoplasma DNA was detected throughout the growing season in roots, stems and young but not mature leaves. Electron microscope examination of the ultra-thin sections of the leaf and stem of diseased magnolias showed collapsed and degenerated sieve tube elements with wall thickening. The reduced lumen of these sieve elements contained numerous vesicles and membrane-bound structures, but no typical phytoplasma cells. This is the first report of aster yellows phytoplasma in magnolia identified by molecular assays.     

华南五针松叶发育的研究

利用光学显微镜和电子显微镜对华南五针松叶的生长和发育进行研究,结果表明:华南五针松叶为单脉序的三棱形针状叶,气孔分布在腹面,为单环型;皮下层一到两层;内皮层明显;转输组织为松型;树脂道三个,出现两个边生、一个中生或缺,三个中生,三个边生,仅二个中生等类型;叶缘的细齿由表皮细胞壁形成。气孔器发育方向是先中央后两端,在部分区域具有合并及不连续的现象。