Early detection of Neophysopella tropicalis in grapevine leaves and on spore traps by qPCR

Neophysopella tropicalis, one of the causal agents of Asian grapevine leaf rust (AGLR), can cause severe epidemics in Brazil that lead to yield losses in commercial vineyards. An early detection of the pathogen by air sampling of urediniospores on spore traps or in symptomless leaves would be valuable to multiple studies, such as epidemics modelling, risk forecasting, monitoring of pathogen introductions in rust-free areas, and predicting the beginning of epidemics. This study developed a quantitative PCR (qPCR) protocol to quantify N. tropicalis urediniospores attached to adhesive tapes and in grapevine leaves before symptom appearance. A specific primer pair was designed based on the internal transcribed spacer (ITS) sequence region of the AGLR pathogen. Standard amplification curves using genomic DNA from urediniospores of N. tropicalis and from urediniospores attached to adhesive tapes were established. Grapevine leaves inoculated with N. tropicalis were collected at 2, 5, and 7 days postinoculation (dpi). One primer pair (580F/720R) amplified a 140 bp product in all AGLR isolates but did not amplify products of other rust genera, such as Phakopsora, Puccinia, Hemileia, Tranzschelia, Cerotelium, and Coleosporium. As little as 0.1 pg DNA and 10 urediniospores of N. tropicalis attached to adhesive tapes could be detected. qPCR enabled the detection of the pathogen as early as 2 dpi, before symptom appearance. This method can be used to monitor N. tropicalis inoculum in grapevine-growing areas and to quantify symptomless infections of the AGLR pathogen.     

甘蔗属及近缘属8种植物叶片下表皮的解剖研究

观察了云南省 8种甘蔗属及近缘属植物叶片下表皮的解剖结构 ,结果表明 ,肋区中刺细胞的有无、行数及形状 ,硅细胞及栓细胞的排列方式 ,表皮上附属物的类型 ,气孔的行数及副卫细胞的形状等在不同种之间是不同的 ,这些解剖特征可作为外部器官形态分类的补充 ,也可为甘蔗杂交育种提供解剖学依据     

New approaches to basic population ecology studies: Revealing more complex patterns of a small Characidae that inhabit streams

Bayesian inference was used to estimate the main population parameters (sex ratio, L₅₀, LWR and somatic growth) and to evaluate sexual dimorphism and growth patterns (isometric/allometric and monophasic/biphasic growth) of Astyanax paranae of the Upper Paraná River. This study brings three statistical differentials: (a) the reparametrisation of the logistic model as a function of L₅₀; (b) the reparameterisations of the LWR models based on the exponential of a piecewise linear regression to evaluate the hypotheses of polyphase growth; and (c) the first application of the recently proposed somatic growth models based only on length data to real data, as well as its expansion and generalisation. The models estimated L₅₀ of females at 37.75 mm and sex ratio at 1.4 females per male. LWR models showed that both sexes presented biphasic growth with a lower increase in weight for males in first stanza. In second stanza, both sexes presented a greater increase in weight. Growth models showed that the growth rates were low, equal for both sexes in early life and slightly higher for females after the eighteenth months old. The studied population inhabits streams, therefore being exposed to constraining conditions that can limit the expression of their whole growth potential since they prioritise energy allocation for reproduction and survival, including reducing L₅₀ in order to ensure the maintenance of the population. Finally, the complex biological patterns that arose from the proposed LWR and growth models demonstrated high potential and applicability for population studies.     

芥菜型油菜(Brassica Juncea)杂种优势利用的研究

1973年,本院发现芥菜型油菜雄性不育株后,经连续几年研究,1975年育成了欧新 A 不育系,欧新 B 保持系和74243—6恢复系,实现了芥菜型“三系”配套。多年来连续测定表明,育成的芥菜型“三系”表现育性稳定,欧新 A 不育系的不育株率达100%,单株自交结实指数平均在0.000—0.103之间。恢复株率为99.54～100%,F_1杂种有较强的苗期优     

Composition and biological activity of essential oils against Metopolophium dirhodum (Hemiptera: Aphididae) cereal crop pest

BACKGROUND: Natural pesticides based on plant essential oils may represent alternative crop protectants. This study analysed the chemical constituents and bioactivities of essential oils from Schinus areira L., Rosmarinus officinalis L. and Tagetes terniflora Kunth against winged and wingless adults of Metopolophium dirhodum (Walk.). RESULTS: The major component of S. areira was α‐phellandrene, that of R. officinalis was 1,8‐cineole and that of T. terniflora was cis‐ocimene. Rosemary essential oil was more effective than the others in immersion method tests. In contact toxicity, the rosemary oil was the most toxic to wingless adults and the S. areira leaf oil was the most toxic to winged adults. All the EOs produced some degrees of repellency in adults and effects on the reproduction and demographic parameters. CONCLUSION: These results showed that the essential oils from S. areira, R. officinalis and T. terniflora could be used as an alternative in the management of M. dirhodum. Copyright © 2012 Society of Chemical Industry     

Spatial patterns of soil attributes and components in a mangrove system in Southeast Brazil (São Paulo)

Purpose

Among environmental factors governing innumerous processes that are active in estuarine environments, those of edaphic character have received special attention in recent studies. With the objectives of determining the spatial patterns of soil attributes and components across different mangrove forest landscapes and obtaining additional information on the cause–effect relationships between these variables and position within the estuary, we analyzed several soil attributes in 31 mangrove soil profiles from the state of São Paulo (Guarujá, Brazil).

Materials and methods

Soil samples were collected at low tide along two transects within the Crumahú mangrove forest. Samples were analyzed to determine pH, Eh, salinity, and the percentages of sand, silt, clay, total organic carbon (TOC), and total S. Mineralogy of the clay fraction (<2 mm) was also studied by X-ray diffraction analysis, and partitioning of solid-phase Fe was performed by sequential extraction.

Results and discussion

The results obtained indicate important differences in soil composition at different depths and landscape positions, causing variations in physicochemical parameters, clay mineralogy, TOC contents, and iron geochemistry. The results also indicate that physicochemical conditions may vary in terms of different local microtopographies. Soil salinity was determined by relative position in relation to flood tide and transition areas with highlands. The proportions of TOC and total S are conditioned by the sedimentation of organic matter derived from vegetation and by the prevailing redox conditions, which clearly favored intense sulfate reduction in the soils (～80% of the total Fe is Fe-pyrite). Particle-size distribution is conditioned by erosive/deposition processes (present and past) and probably by the positioning of ancient and reworked sandy ridges. The existing physicochemical conditions appear to contribute to the synthesis (smectite) and transformation (kaolinite) of clay minerals.

Conclusions

The results demonstrate that the position of soils in the estuary greatly affects soil attributes. Differences occur even at small scales (meters), indicating that both edaphic (soil classification, soil mineralogy, and soil genesis) and environmental (contamination and carbon stock) studies should take such variability into account.

     

Histopathology of black spot symptoms in sweet orange<Emphasis Type="Italic">s</Emphasis>

In Brazil, citrus black spot (CBS) caused by Guignardia citricarpa is a major disease that has different symptoms on fruit. In this study, fruit of Citrus sinensis infected by G. citricarpa and showing the symptoms false melanosis, freckle spot and hard spot were cross-sectioned and analysed anatomically and histochemically by light microscopy. Immuno-histological assays were performed. All symptoms were accompanied by a thickening of the cuticle. False melanosis lesions did not contain pycnidia and remained restricted to the epicarp or to the first layers of the mesocarp. The stomata in this type of lesion showed phenolic compounds in the guard cells and in the sub-stomatal chamber. In some samples, the guard cells and their surrounding cells lysed, and a wound meristem began to form underneath them. Freckle spot and hard spot lesions had very similar histological alterations to the epicarp and mesocarp, but in our samples only hard spot lesions contained pycnidia. Both of these symptoms were accompanied by protein inclusions. Epidermal and sub-epidermal cells located in the oil-gland region were obliterated, causing alterations in these structures. All symptoms had regions that stained strongly for lipids and phenols.     

Immunogenicity in dogs of three recombinant antigens (TSA, LeIF and LmSTI1) potential vaccine candidates for canine visceral leishmaniasis

Control of canine visceral leishmaniasis (VL) remains a difficult and serious problem mostly because there is no reliable and effective vaccine available to prevent this disease. A mixture of three recombinant leishmanial antigens (TSA, LeIF and LmSTI1) encoded by three genes highly conserved in the Leishmania genus have been shown to induce excellent protection against infection in both murine and simian models of cutaneous leishmaniasis. A human clinical trial with these antigens is currently underway. Because of the high degree of conservation, these antigens might be useful vaccine candidates for VL as well. In the present study, using the dog model of the visceral disease, we evaluated the immunogenicity of these three antigens formulated with two different adjuvants, MPL-SE and AdjuPrime. The results were compared with a whole parasite vaccine formulated with BCG as the adjuvant. In order to investigate if sensitization with the recombinant antigens would result in recognition of the corresponding native parasite antigens upon infection, the animals were exposed for four weeks after the termination of the immunization protocol with the recombinant antigens to a low number of L. chagasi promastigotes, an etiological agent of VL. Immune response was evaluated by quantitative ELISA in the animal sera before and after exposure to the viable parasites. Both antigen specific IgG1 and IgG2 antibody levels were measured. Immunization of dogs with the recombinant antigens formulated in either MPL-SE or AdjuPrime resulted in high antibody levels particularly to LmSTI1. In addition, this immunization although to low levels, resulted in the development of antibody response to the whole parasite lysate. Importantly, experimental exposure with low numbers of culture forms of L. chagasi promastigotes caused a clear boost in the immune response to both the recombinant antigens and the corresponding native molecules. The boost response was predominantly of the IgG2 isotype in animals primed with the recombinant antigens plus MPL-SE. In contrast, animals primed with the recombinant antigens formulated in AdjuPrime as well as animals vaccinated with crude antigen preparation responded with mixed IgG1/IgG2 isotypes. These results point to the possible use of this antigen cocktail formulated with the adjuvant MPL-SE in efficacy field trials against canine VL.     

Dams in the Amazon: The importance of maintaining free-flowing tributaries for fish reproduction

1. Free-flowing tributaries are important for the maintenance of fish diversity in dammed systems. In relation to the reproduction of fish species, the role of a free-flowing tributary was evaluated and compared with that of a dammed tributary downstream of large dams in the Madeira River, one of the main tributaries of the Amazon River.
2. Two hypotheses were tested: (i) the densities of the ichthyoplankton differ between the dammed and the free-flowing tributaries; and (ii) the free-flowing tributary contributes a greater diversity of fish larvae species to the assemblage structure of the main stem than the dammed tributary.
3. Fish eggs and larvae were sampled at five sites: one in each tributary (Jamari – dammed – and Machado – free-flowing) and three in the main stem (Madeira River), upstream and downstream from the mouth of each tributary.
4. Fitted Bayesian models showed that the densities both of eggs and larvae were more than twice as high in the free-flowing tributary than in the dammed tributary. The results also indicated that the free-flowing tributary makes a major contribution to the fish assemblage structure of the Madeira River, whereas the dammed tributary does not have a significant influence on the main stem assemblage structure.
5. The results demonstrate the importance of conservation and maintenance not only of the Machado River but also of other free-flowing tributaries in dammed basins, especially those basins with high biodiversity, such as the Amazon. Moreover, this study helps inform the decision-making process regarding the location of new dams, which is critical in fish diversity conservation.

     

甘蔗近缘野生种蔗茅EfGRAS基因克隆及表达分析

为深入挖掘甘蔗品种的抗旱性能,本研究挑选甘蔗品种中参与调控抗旱机制的主要转录因子GRAS的基因进行表达分析。从转录组数据库中调取GRAS转录因子基因序列信息,采用RACE-PCR和qRT-PCR技术从‘蔗茅99-2’中克隆得到1个GRAS基因,将其命名为EfGRAS（GenBank登录号MT499789）,并对其进行生物信息学分析与干旱胁迫表达分析。结果表明,EfGRAS基因编码547个氨基酸,CDS全长1644 bp,该蛋白的分子式为C₂₆₄₅H₄₁₄₉N₇₄₇O₈₁₆S₂₁,相对分子质量为60.14 kDa,不稳定系数为54.85,脂肪系数为84.37,GRAVY值为?0.293,是一类不稳定蛋白和亲水蛋白;亚细胞定位表明其位于细胞核内,EfGRAS蛋白主要的二级结构是α-螺旋和无规则卷曲,与高粱亲缘关系最近;qRT-PCR分析显示,受到干旱胁迫后,‘蔗茅99-2’中基因表达量相比于对照组上调约57.6倍,‘滇蔗01-58’中基因表达量相比于对照上调约27.4倍,‘崖城89-9’中基因表达量相比于对照组上调倍数较低。本研究结果为进一步研究EfGRAS基因在甘蔗中的功能提供理论基础。