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Title: The effect of salicyclic acid on the responses of plants to heat stress and virus infection
Author: Carson, R.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2000
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Salicyclic acid (SA) is an important signalling molecule in plants that is involved in resistance to biotic and abiotic stresses. I examined the effect of SA on induced thermotolerance and heat shock protein (HSP) gene expression in plants. At the beginning of this project a number of studies had already been carried out with animal cells that indicated a link between salicylates and heat shock. However, no similar studies had been conducted in plants. In this study I demonstrated that SA inhibits the acquisition of induced thermotolerance in tobacco (Nicotiana tabacum L.). I investigated the possibility that SA exerts this effect by decreasing Hsp70 gene expression. However, no consistent relationship between Hsp70 gene expression and the SA-induced breakdown in thermotolerance was found. This suggests that SA is interfering with the gene expression or activity of some other HSP family, or of unknown factors. In addition to this work I have investigated the effect of SA on a plant DNA virus. It had already been shown that SA induces resistance to several positive-sense RNA viruses. I found that in Arabidopsis thaliana SA caused a significant delay in the development of symptoms induced by cauliflower mosaic virus (CaMV), a plant DNA virus. This correlated with inhibition of CaMV coat protein, as well as viral DNA and RNA, accumulation within whole Arabidopsis plants. Dissection of SA-treated, CaMV-inoculated plants revealed that SA was either suppressing CaMV replication, or cell-to-cell movement, leading to prevention of the exit of the virus from the inoculated leaf. In tobacco, SA-induced resistance to RNA viruses is antagonised by watering the plants with salicylhydroxamic acid (SHAM), an inhibitor of the mitochondrial alternative oxidase. In this study, watering Arabidopsis plants with SHAM did not antagonise SA-induced resistance to either CaMV, or to an RNA virus, turnip vein clearing virus.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available