Ultrastructure of ray parenchyma cells in the wood of Melia azedarach L. (Meliaceae)

Summary The fine structure of ray parenchyma cells in the sapwood during its transformation to heartwood in Melia azedarach L. (Meliaceae) is described. They have thick walls with electron dense and opaque lamellations. Many branched and unbranched plasmodesmatal connections are present on their lateral and end walls. The cells in the outer sapwood show abundant starch which disappears completely in the inner sapwood ant at the sapwood-heartwood boundary. The morphological features of the starch grain during its depletion are described and their association with lipid formation is indicated. It is suggested that the phenolic materials in the heartwood cells are formed at the sapwood-heartwood boundary.Abbreviations Cy Cytoplasm - ER Endoplasmic reticulum - L Lipid droplet - M Mitochondrion - ML Middle lamella - MVB Multivesicular body - N Nucleus - P Pit-field - PC Pit cavity - PD Plasmodesmata - PL Plasmalemma - St Starch - V Vacuole - VS Vesicle - W Wall The authors thank the Council of Scientific and Industrial Research and University Grants Commission, New Delhi, India for the financial assistance     

Insecticide detoxification indicator strains as tools for enhancing chemical discovery screens

BACKGROUND: Insecticide discovery screens carried out on whole organisms screen for potency resulting from chemical activity at the target site. However, many potentially insecticidal compounds are naturally detoxified in vivo and do not make it to the target site. It is hypothesised that insect strains with their xenobiotic detoxification machinery compromised could be used to identify such compounds that normally fail to show up in screens; these compounds could then be more rationally designed to increase their bioavailability. This strategy was tested with transgenic Drosophila lines with altered expression of Cyp6g1 and Dhr96. RESULTS: It was observed that Cyp6g1 knockdown transgenic lines have increased susceptibility to the test compound imidacloprid, while Dhr96 knockdown transgenic lines are resistant. Evidence was found for a systemic response to xenobiotic exposure, uncovered by piperonyl butoxide treatment and by gene expression profiling. Sex-specific gene expression regulated by DHR96 was also observed. CONCLUSION: The results confirm that this approach to chemical discovery could identify compounds that escape traditional screens. The complexity of the system means that a panel of single and multiple gene knockdown transgenic lines may be required. Copyright © 2011 Society of Chemical Industry     

Advances in physiological mechanisms of spikelet fertility in rice at flowering stage under high temperature stress

全球气候变暖产生的局部短期极端高温,会对水稻形成高温胁迫,影响水稻的各种生理代谢过程,其出现频率有增加趋势.高温胁迫对水稻的影响主要是在开花期,极易导致严重的颖花不育.水稻耐高温胁迫能力存在基因型间的差异.在当天温度较低的时段开花,花粉活性高,花药长,花药基部开裂长度较长、开裂孔较大,是水稻耐高温胁迫的重要表型指标.热激蛋白的表达,提高花药的抗氧化能力,以及维持结构蛋白、酶和细胞膜的稳定性是增强柱头及柱头上花粉粒耐高温胁迫的重要生理机制.目前,国内外学者对高温胁迫影响水稻颖花受精结实的特征、水稻耐高温胁迫的形态与生理机理方面进行了大量研究,但未深入研究缓解水稻高温胁迫伤害的方法与策略,今后应结合水稻耐高温胁迫的形态与生理机理,加强有效缓解高温胁迫方法的探索与研究.     

Study of Cotton Fibre Traits Inheritance under Different Temperature Regimes

Genetic behaviour of fibre quality parameters under heat‐stressed conditions clearly reflected the significant effect of heat stress on the phenotypic expression of fibre quality parameters. Results from the field experiments demonstrated that fibre quality was better among the upland cotton cultivars under non‐stressed (June) regime. Fibre length, strength, uniformity and fineness were substantially high under June regime when compared with that under April (heat stressed) regime. The prevalence of significant genotype × temperature regime interaction for fibre length, fineness and strength provided another evidence for the influence of temperature regimes on the expression of fibre traits. A significant effect of heat stress on the phenotypic expression of fibre quality parameters was observed.     

Evaluation of sugar and organic acid composition and their levels in highbush blueberries from two regions of China

Sweet and sour are the most important taste of blueberries, and they are produced by sugar and acid, respectively. Their contributions to the taste depend not only on the levels of sugar and acid, but also on the types and relative proportions of sugar and acid. Therefore, it is very important to evaluate the composition and levels of sugar and acid in blueberries. Regional differences and variety diversity also affect the sugar and acid characteristics of fruits. Therefore, this study selected two main producing regions in northern China(Weihai and Yingkou) to examine the sugar and acid characteristics of 11 common blueberry cultivars. The indexes measured included soluble sugars, organic acids, soluble solid content and titratable acidity. The results showed that glucose and fructose were the major sugars, and citric acid and quinic acid were the major organic acids. Correlation analysis showed that glucose, fructose, and sucrose were positively correlated with total sugar content; the citric acid content was positively correlated with the titratable acidity and total organic acids. Titratable acidity, glucose, fructose, sucrose, total sugar content, citric acid, shikimic acid and total acid content of the blueberries varied significantly between regions(P0.05). In general, compared with Weihai blueberries, Yingkou blueberries had higher sugar content and lower acid content. The results of this study may provide useful references for the evaluation of sweet and sour flavors and cultivar selection of blueberries.     

Identification of factors associated with white mould in snap bean using tree-based methods

Most processing snap bean fields are treated with fungicides at flowering to suppress white mould, one of the more significant diseases of this crop. Farmers would like to know when their fields are at sufficient risk of white mould, to plan fungicide applications or avoid spraying if the risk is below a tolerable threshold. In 2006, 2007 and 2008, observational data were collected from processing snap bean fields across western and central New York State, USA. White mould was found in 20% of fields. Boosted regression trees were used to model white mould presence or absence in a field (a binary response variable) as a function of agronomic and edaphic variables, and macroscale drought indices. The five most important predictors were canopy openness during pod development, the number of days after planting, hydrologic soil group, canopy openness during bloom and elevation. The risk of white mould increased by about 20% when canopy openness was less than 20 cm at the bloom stage and c. 30% when canopy openness was less than 30 cm at the pod stage. The most relevant interaction was between canopy openness at the pod stage and hydrologic soil group. A random forest model for predicting the presence of white mould by bloom had an estimated classification accuracy of 73%. The extension of these results to remote forecasting of white mould in processing snap bean production is discussed.     

Allelic Variation within Single Podded Gene Characterized by STMS Marker in Chickpea

Chickpea （Cicer arietinum L.）, is an important grain legume crop throughout the world especially in developing countries. However the average yield worldwide is considered to be lower than its potential yield （Singh et al., 1994）. The average yield of chickpea is much lower in Pakistan, which is about 5500-650 kg/hm^2 due to various abiotic and biotic stresses （Shah et al., 2005）.