Full text
| |
| Author(s): |
Isabela Amaral de Camargo
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB) |
| Defense date: | 2013-08-05 |
| Examining board members: |
Antonio Vargas de Oliveira Figueira;
Hugo Bruno Correa Molinari;
Rafael Vasconcelos Ribeiro
|
| Advisor: | Antonio Vargas de Oliveira Figueira |
| Abstract | |
Sugarcane cultivars with drought tolerance and high yield are highly desirable to the rapid expansion of sugarcane plantings to regions characterized by a period of prolonged water deficit. Water deficit stress in plants induces oxidative damage due to the increase of the production of reactive oxygen species (ROS) without their subsequent control. Drought tolerance may derive from distinct mechanisms that allow plants to maintain metabolism at normal levels, requiring a robust antioxidant system to inactivate ROS, which consists of enzymatic pathways including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST) and glutathione peroxidase (GPX). The elucidation of the biochemical and molecular mechanisms adopted by sugarcane in response to water deficit would be relevant to the development of tolerant cultivars, contributing to the reduction in the requirement for irrigation. Two cultivars selected based on their contrasting behavior in response to drought were evaluated, \'IACSP94-2094\' selected as tolerant, and \'IACSP97-7065\' as more sensitive to drought. Water deficit was imposed by withholding water in plants 4 months after planting in the greenhouse. Water stress was indicated by both leaf water potential and the leaf relative water content (CRA), together by the reduction in CO2 assimilation (A), stomatal conductance (gS), transpiration (E) in both cultivars. A decrease in quantum yield of photochemistry from photosystem II corroborated the occurrence of water deficit for \'IACSP94-2094\', together with results from lipid peroxidation analysis, indicator of oxidative stress. In relation of the specific activity and gene expression of antioxidant enzymes system, it was demonstrated that superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR) were the key enzymes controlling oxidative stress triggered by drought in the tolerant cultivar. SOD isoform activity profiles showed that the tolerant cultivar (\'IACSP94-2094\') displayed more isoforms than the sensitive cultivar (\'IACSP97-7065\'), with the Fe-SOD being the most representative. Proline and phenolic compound contents in leaves did not show direct relationship with response to drought for \'IACSP94-2094\', and only under maximum water deficit \'IACSP97-7065\' presented increments in the phenolics content, suggesting that cultivars can adopt alternative mechanisms to overcome the harmful effects of dry (AU) | |
| FAPESP's process: | 10/13579-9 - Sugarcane antioxidative system in response to drought |
| Grantee: | Isabela Amaral de Camargo |
| Support Opportunities: | Scholarships in Brazil - Master |