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| Author(s): |
Adriana Yepes Mayorga
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2010-12-09 |
| Examining board members: |
Marcos Silveira Buckeridge;
Marília Gaspar;
Sergio Tadeu Meirelles;
Helenice Mercier;
Henrique Pessoa dos Santos
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| Advisor: | Marcos Silveira Buckeridge |
| Abstract | |
The continuous rise in anthropogenic CO2 concentration has the potential to lead to an approximate 3°C increase in temperature worldwide and these is thought as being important factors that affect the plants productivity and distribution. Hymenaea courbaril L., jatobá, is a late-successional species that is recognized by its ecological importance and by their distribution from central America to the south of Brazil. This plant species has been used as a model for the studies of cell wall storage carbohydrates mobilization, as well as for the studies of Neotropic species responses to enrichment CO2 atmosphere. It is known that XG mobilization products are driven primarily to expanding leaves. Elevated temperatures promote this mobilization process. In the present work, he initial development of seedlings of Hymenaea courbaril was investigated in order to understand aspects of physiological bevavior and carbon metabolism under elevated CO2 concentrations (e CO2) and/or elevated temperature (eT, +3°C). The results showed that the e CO2 and eT, when associated, actively improved H. courbaril L. young plants development, promoting the maturation of its delayed greening leaves with a higher and a faster chlorophyll accumulation. Such interaction seems to block the reduction of XG mobilization and the photosynthesis acclimation, previously observed to be promoted by the elevated CO2 atmosphere. It was observed that eCO2 increases net assimilation CO2 rates and the non structural carbohydrates production, like starch. Elevated temperatures improved the metabolism in general and this seems to depend on the carbohydrates status. Elevated temperatures enhanced the sucrose synthesis, diminished the starch production, and the starch/sucrose ratio during the night. The metabolic features observed for Hymenaea courbaril are likely to be associated he sugar sensing mechanism, which reduces the photosynthetic enzymes synthesis reduction (photosynthesis acclimation). The jatobas initial development showed two phases determined by its storage compounds in the cotyledons. The first is a linear growth period during which XG mobilization, photosynthesis and a high starch level is stored in the stem, the latter possibly used as a supplementary carbon source until photosynthesis is fully established. The second phase is growth stabilization, once the stem starch reserves are utilized. At that point, the growth sink forces diminish and consequently an increased concentration of starch is obseved in the completed expanded leaves. Considering those strategies, without water stress, the conditions of elevated CO2 and elevated temperature promote growth of young H. courbaril plants. (AU) | |
| FAPESP's process: | 06/61544-4 - Physiological and metabolic responses of three species of tropical legumes to global climate changes |
| Grantee: | Adriana Yepes Mayorga |
| Support Opportunities: | Scholarships in Brazil - Doctorate |