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Förslaget inkom 2006-01-18

Aphid induced callose production and phloem transport in barley, studied in South-Africa

OBS! ANSÖKNINGSTIDEN FÖR DETTA EXJOBB HAR LÖPT UT.
Plants have evolved many different mechanisms for defence against pathogens and herbivores and for the competition with other plants. An increased knowledge of these mechanisms might help in finding resistant varieties and result in the decreased use of synthetic chemicals in agriculture. One of our projects concern defence responses induced by aphids in barley. Aphids are inserting their stylet into the phloem and drain the sugar and other nutrients that are transported in the phloem. A collaborating group in South-Africa have shown that in wheat plants, the Russian Wheat Aphid induces the production of the polysaccharide callose. This compound blocks the phloem tubes and thus the transport in the plant. In a comparative study, the effect of aphids on susceptible and resistant wheat varieties were investigated. It was shown that the resistant plants did not produce callose and that the transport was not blocked. This indicates that the resistant variety was in fact tolerant to aphid feeding by ignoring the nutrient drain that they impose on the system. To find out whether similar mechanisms occur in other combinations of plant and aphid, callose production and transport function will in this project be studied in barley plants, infestated by the bird cherry-oat aphid (Rhopalosiphum padi). This aphid is a serious pest in Sweden, but it does not, as the Russian Wheat aphid, cause visible damage to the plants. The production of callose will be studied by staining plant tissue with aniline blue and recording the staining using a fluoromicroscope. The transport in phloem will be followed after the addition of the fluorescent compound 5,6-carboyxyfluorescine to the plant tissue. If time allows, callose production will be studied using electron microscopy.

A suitable background is a program in biology, biotechnology, environmental sciences or agriculture with training in plant physiology and anatomy.

The department of chemistry, biology, geography and environmental sciences at Södertörn University College has about 150 members, of which about 50 post-graduate students. The department has an active research focused on the life sciences. The proposed project will be carried out in collaboration with a research group in South-Africa, where the major part of the experimental work will be carried out.


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