No abstract

Aphids feeding on plants experience similar responses to pathogens due to the prolonged and intimate contact with the plant. Diuraphis noxia is an economically important aphid pest on wheat that exhibits such an interaction. Studies on small RNA (sRNA) that regulate genes imparting resistance to wheat against D. noxia have predicted an Argonaute 5 (TaAGO5) gene as possible role player in the resistance response. Functional characterization revealed that TaAGO5 is crucial in regulating the response to infestation by D. noxia. Knockdown of TaAGO5 by 22% in D. noxia resistant wheat resulted in a completely susceptible phenotype. The fecundity and stress levels of D. noxia feeding on these silenced plants were similar to aphids feeding on the susceptible controls. Thus, TaAGO5 is crucial in the defense response by wheat plants during aphid feeding and this is similar to Nicotiana benthaminia plants experiencing arthropod herbivory. Additionally, TaAGO5 was differentially regulated by the Barley mosaic virus (BMV) used in the functional characterization. This provides evidence that TaAGO5 could play a role during virus infection of wheat. The role of AGO5 proteins in plant responses to arthropod herbivory and virus infection is known for dicotyledonous plants. Here, we present data that indicate that this role of TaAGO5 is conserved in wheat and possibly for monocotyledonous plants. These observations extend our knowledge on the roles of AGO proteins in plant resistance.

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Microbial growth develops in stored diesel fuel. This can influence later use in emergency backup generators and vehicles through the clogging of fuel filters by the development of biomass. A mutualistic microbial community can develop in stored fuel products that degrade polycyclic aromatic hydrocarbons to the benefit of one another. This project aimed to study the bacterial community profile of diesel obtained from commercial fuel stations using culture dependent and independent methods. Bacteria and total DNA were isolated from the diesel and the community was studied using denaturing gradient gel electrophoresis of the 16S rDNA region. This resulted in the isolation of six bacterial species from two different genera (related to Bacillus and Lysinibacillus) that could grow in pure culture with diesel as carbon source. The denaturing gradient gel electrophoresis analysis indicated the occurrence of an additional eight genera in the sampled diesel. Both methods identified bacteria related to Bacillus pumilus occurring in the samples. Bacillus pumilus was the predominant species (50%) isolated from diesel samples using culture media. The identification of bacteria occurring in commercial diesel samples can be useful in determining the degree of degradation occurring during the storage of the product and also possible bioremediation agents in diesel fuels spills.