| Grant number: | 13/15108-1 |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| Start date: | October 01, 2013 |
| End date: | July 31, 2016 |
| Field of knowledge: | Biological Sciences - Botany - Pant Physiology |
| Principal Investigator: | Helenice Mercier |
| Grantee: | Paulo Tamaso Mioto |
| Host Institution: | Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Associated research grant: | 11/50637-0 - Competence for Crassulacean Acid Metabolism (CAM) expression in epiphytic bromeliad: signaling, modulation of expression, transcriptional profile and interaction with the nitrogen metabolism, AP.TEM |
Abstract Crassulacean Acid Metabolism (CAM) is an important adaptation to low-water environments. Some species are capable of altering their photosynthetic metabolism in response to abiotic stresses, such as drought. CAM up-regulation in tank bromeliads occurs differently along the leaf length, since the apical portion express CAM more strongly than the basal portion of the leaf. Recently, in our laboratory, it was found that nitric oxide (NO) appears to be involved in CAM signaling in Guzmania monostachia, a tank bromeliad. NO was already linked to several processes in plants, but there are wide gaps in the knowledge of how this molecule is synthesized and its mode of action. There are two relatively well established pathways of NO synthesis: the enzyme nitrate reductase (NR) and a pathway called NOS (nitric oxide synthase), in which no enzyme has been characterized. Once synthesized, NO may be transported through S-nitroso glutathione (GSNO) or interact locally with proteins through S-nytrosilation. The aim of this work is to evaluate the production, transport and mechanism of action of NO during CAM induction in G. monostachia a C3-CAM epiphytic tank bromeliad. Detached leaves will be kept in a 30% polyethylene glycol 6000 solution (PEG) in order to simulate drought. The control leaves will be kept in distilled water. CAM induction will be assessed through quantification of phosphoenol carboxylase (PEPC) activity and expression, and nocturnal accumulation of organic acids. During the eight days of experiment, NO emission will be measured and, later, the leaves will be subjected to scavengers or donors of this compound. This approaches will determine if NO levels in the plant change in response to water deficit and if NO is indispensable for CAM up-regulation. NR and NOS pathways will be suppressed separately to determine which one of them contributes more to NO production. GSNO will be quantified to investigate if there is transport of NO along the leaf. Finally, the proteins that are S-nitrosylated in response to water deficit will be characterized, and S-nyrtisylation inhibitors will be given to the plant in order to determine if this process is indispensable for CAM induction. All analyses will be performed in at least two portions of the leaf: basal and apical. The basal portion would be a control, since it does not up-regulate CAM in response to drought. | |
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