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| Author(s): |
Joice Bissoloti Brigati
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2009-04-07 |
| Examining board members: |
Helaine Carrer;
Welington Luiz de Araujo;
Sergio Florentino Pascholati
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| Advisor: | Helaine Carrer |
| Abstract | |
The Brazilian production of oranges is mainly for the industry of concentrated juice, it is the most important citrus product, and the state of São Paulo is the largest producer and exporter of the country. Due to the low genetic variability caused by the multiplication of citrus plants by grafting, this culture became constant target of many pests and diseases. Among all the diseases that lead to elevated damage to the Brazilian citrus plantation, one is very relevant, the Black Spot disease caused by the fungus Guignardia citricarpa Kiely. The control of this disease is done by many sprays of fungicides that significantly increase the production cost to the producers. A possible alternative to control this pathogen is the development of resistant citrus plants to disease through genetic transformation. To that, it is necessary to understand the mechanisms of plant defense response and identify the genes related to the defense. In an attempt to elucidate the responses of this host both,anatomical analysis of sweet orange fruits (Citrus sinensis Osbeck cv. Pêra) inoculated with the pathogen and transcriptional analysis of two cDNA libraries of albedo section were done. One was from health fruits (BAFS) and another from albedo of fruits inoculated with the pathogen (BAFC). The analysis showed that the anatomical damage caused by the pathogen in the plant shall begin 24 hours after inoculation showing lesions on epicarp cells, and continue gradually until 72 hours also showing a decrease in the amount of starch and accumulation of phenolic compounds. It was obtained 184 valid ESTs of the BAFS and 370 from BAFC. The annotation and categorization of these sequences showed that the transcriptional profile in the two libraries were similar, however, in BAFC, were found transcripts belonging to plant defense such as catalase, the glutathione and monooxygenases. These analyses showed that the plant defense response begins with lesions in the cells, being it cost-intensive interaction for the host, (with reduction of starch reserves) and the plant defense to resistance is related to many genes. (AU) | |