| A haustorium of Blumeria graminis in an epidermal cell of barley. The cell is dead, the protoplast has shrunken away from the wall, and the remaining space has been infused with 6-carboxyfluoroscein diacetate. The specimen came from plants about 9 days after infection.
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| the same cell... this time the maximum brightness value for each pixel of all the confocal optical sections has been plotted: note the very bright donut shaped ring. The hole in the middle is where the fungal appressorium has penetrated the cell wall; the very bright region surrounding it is most likely a papilla (or remains thereof) - a localised region of callose and phenolic deposition coupled with extensive oxidative protein cross linking acting as an induced structural defence against penetration.
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| Investigators |
| Keith Stewart (DPhil. candidate), Department of Plant Sciences, University of Oxford, U.K.
Dr. Sarah Gurr, Plant Sciences, University of Oxford, U.K.
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What is the Issue? |
| PLANT PATHOLOGY |
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The genes that help plants survive harsh environmental conditions such as drought, cold and saline (salty) soils, also help plants fight disease. When harsh conditions are reduced, plant metabolisms can change, lowering their resistance to disease (mlo breakdown). This is the case with spring barley, which becomes more susceptible to the devastating powdery mildew disease (Blumeria [Erysiphe] graminis f. sp. hordei) when environmental stress, especially drought stress, is removed. This work is investigating this relationship to better understand the interaction between stressed plants and agents of disease. Since the principles of leaf physiology (functioning) are the same in trees as they are in barley, research findings will be applicable to forest health and management.
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What is our goal? |
| UNDERSTANDING RESPONSE OF FOOD PLANTS UNDER STRESS WITH IMPLICATIONS TO GLOBAL CLIMATE CHANGE
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| Do droughts make plants stronger? The relationship between harsh environmental conditions and disease resistance in barley. |
Where we currently stand. |
| mlo breakdown occurs when barley is relieved from drought stress, but not when relieved from salt stress. Due to the differential responses of barley to these stresses, investigation has focused on understanding both the whole plant and the physiological responses of barley to salt stress. Work to date has shown that:
1) mlo resistance breakdown occurs following the relief of drought stress whether induced by withholding water, or by the presence of chemical osmotica in the rooting medium; 2) mlo resistance breakdown occurs following the relief of exposure to low temperatures; 3) mlo resistance does not occur following the relief of salt stress; 4) mlo resistance breakdown is not a consequence of differential stress tolerance between resistant and susceptible varieties; 5) fungal development is delayed following the breakdown of resistance; and 6) abiotic stress affects mlo gene expression. Ongoing and future work includes: analysis of mlo gene expression following the onset and relief of drought and cold stress; analysis of stress inducible gene expression following the onset and relief of drought and cold stress; further investigations of fungal development following the relief of abiotic stress; and development of an mlo gene promoter/green fluorescent protein reporter construct for temporal/spatial analysis of mlo gene expression. Understanding the response of plants such as barley to environmental stressors is both commercially and environmentally important, especially within the present changing global climate. It is hoped that results from this study will elucidate the differences between these two different stressors and lead to better understanding of environmental stress on plant life. This project will be completed by September, 2001.
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You can help this project - find out how. |
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