Genetic diversity among Plantagos

Summary In the progenies of the crosses between disomics and trisomies, two plants were isolated which carried an extra chromosome that was unlike any in the standard complement. The plants were not alike; while one carried a metacentric, the other had a telocentric extra chromosome. Their detailed structure and possible modes of origin are discussed.     

A unique histone 3 lysine 14 chromatin signature underlies tissue-specific gene regulation

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A rigorous yet simple quantitative risk assessment method for quarantine pests and non-native organisms

Internationally recognised guidelines for the assessment of risk posed by non‐native organisms generally suggest that the assessment is disaggregated into a series of components each being scored and then the scores added or averaged to give the final result. Assigning odds instead of scores allows a more rigorous probabilistic treatment of the data, which can offer more effective discrimination between organisms. For each component of the assessment, the odds express how likely is the evidence if the organism poses a risk as a quarantine pest. According to Bayesian theory, the odds for all components are multiplied together and the product divided by itself plus one to give the probability that the organism poses a risk as a quarantine pest given the evidence available (assuming that the prior probability is neutral). A general illustration of the different distributions of outcomes obtained from score averaging and probability is provided. The approach is then applied to a set of risk assessments for 256 potential quarantine pests compiled for Tanzania in 1997. The greater discrimination between cases may help improve communication between risk assessment scientists and regulatory decision makers.     

Cytology of the tetraploidAllium ampeloprasum with chiasma localization

Allium ampeloprasum cultivated in Kashmir is a tetraploid. The somatic complement of the cultivar consists of 32 median or submedian chromosomes, of which 8 have secondary constrictions. The tetraploid karyotype exhibits a great deal of heterozygosity which is taken as an evidence in support of the allopolyploid nature of the species. The tetraploid form is represented by the genomic formula AAAA. The three genomes show a great deal of similarity and are therefore taken to represent three varieties which have given rise to this cultivar through hybridity. — Despite this, no multivalents are formed by the species during meiosis. The shift from multivalent to bivalent type of pairing is attributed to the localization of chiasmata around the centromere. This type of chiasmata localization is a means adopted by some polyploid species to stabilize as diploids.     

Within‐field spatial distribution patterns of corn planthopper,Peregrinus maidis,and severity of hopperburn and Maize mosaic virus symptoms as influenced by sunn hemp intercropping

Habitat management (e.g., intercropping) may alter within‐field spatial distribution patterns of herbivores, from a typical pattern as observed in a monoculture, and may influence patterns of crop injury. Field trials were conducted to study the effect of intercropping maize, Zea mays L. (Poaceae), with sunn hemp, Crotalaria juncea L. (Fabaceae) strips on within‐field spatial distribution patterns of corn planthopper, Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae), and combined severity of hopperburn and Maize mosaic virus (MMV) (Rhabdoviridae: Nucleorhabdovirus) symptoms. In each field trial, spatially explicit data on P. maidis counts and ratings of severity of symptoms were obtained by sampling maize plants at weekly intervals. These data were used to examine the spatial patterns of P. maidis and severity of symptoms in maize‐intercropped and monoculture plots with Spatial Analysis for Distance IndicEs (SADIE) methodology. Spatial aggregation patterns of P. maidis in each treatment plot were not consistent among the field trials and tended to be mediated by their population densities. Interpolation of local cluster indices showed that P. maidis were more often aggregated at the field edges, irrespective of treatment. At times of MMV incidence in field trials (fall 2010 and spring 2011), the patch clusters of P. maidis and symptomatic plants were located at the field edges, but were spatially unassociated in both treatment plots. The results provided an approximation of the unpredictability of P. maidis spatial patterns at different population densities and their association with severity of symptoms in two maize‐cropping systems. However, the gap clusters of symptomatic plants were primarily located at the field interiors and were larger in intercropped than in monoculture plots. Such spatial pattern of symptomatic plants resulted in the reduced incidence of MMV in the intercropped plot compared with the monoculture plot, suggesting intercropping sunn hemp can be a useful tool in the management of MMV in maize fields.     

Cinnamate and cinnamate derivatives in plants

Cinnamic acid, an ubiquitous alpha beta unsaturated acid, upon hydroxylation yields p-hydroxy cinnamic acid or p-coumarate, a plant mono phenol. Being, precursor for the production of various di (lignans), polyphenols (lignins) and also substituted derivatives, it seems to be an important aromatic chemical in growth and development of plants. This aromatic chemical substance synthesized primarily by almost all forms of plants, seemingly involves in the regulation of various physiological processes. The presence of this ubiquitous plant alpha beta unsaturated acid and its derivatives have been adopted by plants for various mechanisms. An effort towards the consolidation of these is made here.     

Simple and Rapid Method for Detecting Biofilm Forming Bacteria

Biofilm forming bacteria play a vital role in causing infectious diseases and for enhancing the efficiency of the bioremediation process through immobilization. Different media and conditions have been reported for detecting biofilm forming bacteria, however, they are not quite rapid. Here, we propose the use of a simple medium which can be used for detecting biofilm former, and also provide a mechanism to regulate the expression of biofilm formation process.