Efectos de la sobreexpresión de S-Adenosil-L-metionina descarboxilasa1 en la respuesta a estrés en Arabidopsis.
Polyamines are a group of low molecular weight molecules implicated in a lot of different and essential proceses in plants like the promotion of plant growth and development by activating the synthesis of nucleic acids. Polyamine metabolism has long been known to be altered in plants responding to abiotic environmental stress and to undergo profound changes in plants interacting with fungal and viral pathogens. The most important polyamines are spermidine, spermine and putrescine. These small compounds are positively charged at physiological pH and are known to bind to negatively charged molecules, e.g. nucleic acids, acidic phospholipids and various types of proteins. The biosynthesis of polyamines in Arabidopsis thanliana is a well-known process in which S-adenosylmethionine decarboxylase (SAMDC) contitutes an important metabolic control point. This enzyme catalizes de decarboxylation of S-adenosylmethionine which is also an intermediate product in the synthesis of ethylene. Changes in SAMdC expression have been observed as a response to environmental factors. In this work we have studied the effects of the constitutive overexpression of SAMDC1 under the control of the CAMV-35S promoter in Arabidopsis thaliana plants. Results show that the transgenic lines show a direct increase in levels of spermine. Furthermore, these SAMDC1 overexpressing plant show an induction in the expression levels of a series of genes related to response during salt or drought stress and pathogen infection. There are as well, changes in the expression levels of genes involved in Abcisic acid (ABA) and jasmonic acid biosynthesis. These changes result in a higher tolerance against abiotic and biotic stresses, increased production of ABA, lower levels of ethylene biosynthesis and a series of estructural differences with Col 0 wildtype plants. Further studies in this work have established a direct relationship between the higher levels of espermine and the changes observed in the transgenic plants.
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Advisor:Carrasco Sorlí, Pedro Miguel
School:Universitat de València
Source Type:Master's Thesis
Keywords:bioquímica i biologia molecular
Date of Publication:05/26/2005