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| Author(s): |
Rodolfo Augusto Maniero
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB) |
| Defense date: | 2019-06-28 |
| Examining board members: |
Antonio Vargas de Oliveira Figueira;
Marie Anne van Sluys;
Marcelo Menossi Teixeira
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| Advisor: | Antonio Vargas de Oliveira Figueira |
| Abstract | |
In the growing world demand for clean energy, sugarcane (Saccharum spp.) represents an important crop for low-cost renewable energy generation with low environmental impact. To meet this demand, the use of nitrogen-based fertilization is essential to maintain the productivity levels of the sugarcane crop. However, sugarcane plants present low response to the application of nitrogen-based fertilizers, contributing to environmental pollution and consequent negative impacts on the energy and economic balance for this crop. Ammonium is the preferred source of N absorbed by sugarcane, but knowledge about the regulation of the transport process and the distribution of ammonium in this species remains limited. Ammonium transport in plants is mediated by the AMMONIUM TRANSPORTER (AMT) gene family, but the impact of the functionality of these carriers on the N use efficiency (NUE) in sugarcane requires elucidation. In previous studies, BAC (Bacterial Artificial Chromosome) libraries of AMT2 subfamily with expression in different organs in this species were identified in order to understand the function of these genes in the plant. The present study aimed at the functional characterization of the ScAMT3;3 gene from the AMT2 subfamily of sugarcane in heterologous systems using mutants of yeast (Saccharomyces cerevisiae) and Arabidopsis thaliana, defective in ammonium transport. Yeast complementation with ScAMT3;3 was able to restore the growth of the mutant, besides indicating its functionality for NH3/H+ transport. Experimental localization of ScAMT3;3 promoter activity in Arabidopsis using GUS and GFP reporter genes indicated preferential expression in leaf tissue, mainly in phloem cells, being poorly regulated by the status and source of N. These data corroborate the results obtained from the analysis of relative expression of the gene in sugarcane. Transgenic plants expressing ScAMT3;3 under regulation of the constitutive 35SCaMV promoter generated in the genetic background of the qko mutant (AtAMT1;1; AtAMT1;2; AtAMT1;3 and AtAMT2;1) of Arabidopsis demonstrated that the ectopic expression of ScAMT3;3 helps the influx of 15N-ammonium roots and increases the accumulation of biomass in shoots in the presence of ammonium. Transgenic plants expressing the endogenous promoter and coding region for ScAMT3;3 also presented accumulation of fresh mass in shoots in the presence of ammonia. 15N-ammonium accumulation experiments on leaves indicated that the function of ScAMT3;3 is not associated to the remobilization process in N deficiency, but to the possible translocation process in N availability (AU) | |
| FAPESP's process: | 17/00460-2 - Functional characterization of gene encoding ammonium transporter ScAMT3.3 in sugarcane (Saccharum spp.) |
| Grantee: | Rodolfo Augusto Maniero |
| Support Opportunities: | Scholarships in Brazil - Master |