Rice (Oryza sativa L.) feeds more than half of the world’s population and is rich in genetic diversity, with thousands of varieties grown throughout the world. Iron (Fe) deficiency is a major abiotic stress in crop production, since in calcareous soils, which account for about 30% of the world’s cultivated soils, Fe form soluble complexes and is not readily available for uptake. For a long time plants have been divided into two distinct groups, by their capacity for Fe uptake: dicotyledoneas, that belong to Strategy I and utilize an Fe reduction and Fe2+ transporter system; and graminaceous monocotyledoneas, strategy II plants, that use an phytosiderophore (PS)-based system. Recently, evidences suggest that rice, in addition to use Strategy II, can also use an Fe2+ transporter, typical in Strategy I plants, that could confer advantage in flooded soils where Fe2+ is more available. The aim of this study was to understand if rice plants have or not the capacity to upregulate Strategy I mechanisms for Fe uptake. To meet these purposes, two different rice cultivars with different susceptibilities to Fe deficiency, were grown hydroponically, namely, Nipponbare (whose genome has already been sequenced) and Bico Branco (never studied before) to analyze various parameters at a physiological and molecular level. The results obtained showed that Bico Branco cultivar accumulated more minerals in roots and Nipponbare in shoots and that when Fe uptake is decreased there is an increase on the uptake of some other minerals, mainly zinc (Zn), manganese (Mn) and copper (Cu). In what concerns the photosynthetic pigments, the Bico Branco cultivar showed to be more susceptible to Fe deficiency than the Nipponbare cultivar, as the first developed more chlorosis than the latter. Furthermore, the Nipponbare cultivar revealed the highest Fereductase activity under Fe deficient conditions and revealed higher levels of expression of OsFRO2 gene in the roots, a gene that is responsible for Fe reduction. These new findings show that some rice cultivars may utilize the Fe-reduction system, mainly because rice is known for producing PS in low amounts and grow in aerobic/upland where Fe3+ is more available. Also, new candidate genes in rice were identified, namely OsFPN1, OsFPN2, OsMYB2 and OsMYBS3, and they revealed to be important in Fe homeostasis in rice.
Date of Award | 2014 |
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Original language | English |
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Awarding Institution | - Universidade Católica Portuguesa
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Supervisor | Marta Wilton de Vasconcelos (Supervisor) & Ana Gomes (Supervisor) |
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- Mestrado em Microbiologia Aplicada
Study of the Fe uptake systems in two different rice cultivars
Pereira, A. M. P. (Student). 2014
Student thesis: Master's Thesis