Recent projects

 

Exploring the physiological and molecular aspects of Guzmania monostachia (Bromeliaceae): studying the functional pathways of photosynthesis and nutrient responses

Supported by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) – Proc. n° 2018/12667-3

 

 

Guzmania monostachia is an epiphytic bromeliad with tank and C3-CAM facultative metabolism that survives to intensive environmental variations such as the intermittency of water and nutrient availabilities. Previous researches of our group have shown that this bromeliad is inducible to CAM in water scarcity and under low N availability and can revert to C3 when rehydrated. Considering its photosynthetic plasticity, this bromeliad represents an excellent model to understand the interconnection of CAM (i) with the photochemical phase of photosynthesis and (ii) its regulation by nutrients, mainly by nitrogen and potassium. Since the CAM metabolism allow plants have a higher water use and N efficiencies and that we are already facing an increase of the arid and oligotrophic areas in the Earth, it becomes essential to unravel the physiological strategies that certain bromeliads have to withstand the water and nutritional stresses. In this sense, from the sequencing and reassembling of the G. monostachia transcriptome previously made by our group, we could notice different transcriptional profiles along the foliar limb due to variations in nutritional and water availabilities, and we selected two functional pathways from these results to continue our physiological and molecular researches: photosynthesis and nutrient responses.

 

Nitrogen metabolism and its interaction with the Crassulacean Acid Metabolism (CAM) in Guzmania monostachia (Bromeliaceae): a physiological and molecular approach

Supported by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) – Proc. n° 2016/09699-5

 

 

The Crassulacean Acid Metabolism (CAM) allows the assimilation of CO2 with a greater water use efficiency rather than the C3 and C4 metabolisms. In the epiphytic C3-CAM facultative bromeliad Guzmania monostachia (Bromeliaceae, Tillandsioideae), the C3 maximizes its growth under favorable environmental conditions, while CAM is manifested in stressful conditions. Since different nitrogen sources (i.e., inorganic and organic) are available in the nutrient-poor epiphytic environment, changes in the availability of nutrients and water can modulate physiological and molecular responses in G. monostachia in order to improve the nitrogen use efficiency and the expression of CAM. In this context, this project aims to investigate differences in the physiology and molecular biology related to nitrogen metabolism (absorption and assimilation) in different nitrogen sources (ammonium, nitrate or urea), and their role in photosynthetic modulation in G. monostachia in variable scenarios of nitrogen and water availability. Specifically, this study intends to answer the following questions: (1) Does G. monostachia have a preference for some source of nitrogen? Would it be organic or inorganic? (2) How do the transport and assimilation of different forms of nitrogen occur and where are they processed? (3) Is there a change in gene expression activating high-affinity transporter genes at low nitrogen concentrations? (4) Does nutritional preference of G. monostachia change over time by the combined presence of more than one form of nitrogen? (5) Do different nitrogen sources modulate CAM photosynthesis in this bromeliad species, showing an association between nitrogen and CAM expression under drought conditions? Does the expression of the specific CAM-PEPc gene be variable?

 

Improving the efficiency of water- and nitrogen-use by crop plants

Supported by FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) – Proc. n° 2015/50109-4

 

This project consists of two annual components: one visit each year by a postgraduate student from USP to University of Oxford (UK) and one visit each year by the two main researches (from São Paulo to Oxford and from Oxford to São Paulo). Reflecting this structure, the aims of the project will be subdivided into three main components:(a) the visiting postgraduate researcher from USP will conduct tests in Oxford to determine whether the newly suggested model for regulation of CAM photosynthesis (and hence plant water-use) by nitrogen availability,endogenous hormones and ROS is broadly applicable to inducible CAM plants. (b) As part of the project to be developed in Brazil, during the visit of the Oxford researcher to USP, we will initiate a systematic screening of bromeliads endemic to Southeastern Brazil to identify further species that are potentially capable of switching between CAM and C3 photosynthesis. (c) As part of the project to be developed in Oxford, during the visit of the Brazilian researcher to University of Oxford, we will discuss the newly obtained results and plan other assays. During this period we will also begin writing manuscripts and research/funding projects.