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- Comparative analysis of Iron Deficiency Chlorosis responses in soybean (Glycine max) and barrel medic (Medicago truncatula)Publication . Santos, Carla S.; Serrão, Inês; Vasconcelos, Marta W.Legume grains have an important socio-economical role, being highly utilized in human and animal nutrition. Although iron (Fe) is abundant in the earths crust, its limited solubility makes it poorly bioavailable for plants, contributing to iron deficiency chlorosis (IDC). In this work the physiological and molecular mechanisms associated with IDC were studied, namely, the mechanisms involved on Fe deficiency response, as well as a new Fe metabolism related gene in two important legume crops, Glycine max and Medicago truncatula. Fe deficient plants developed: decreased root and shoot length, increased number of secondary roots and lower chlorophyll levels. Fe shoot content decreased six- and 11-fold for G. max and M truncatula in Fe-deficiency. Whilst in G. max roots no significant differences were detected, in M. truncatula roots Fe decreased nine-fold in Fe-deficiency. Genes involved in Fe uptake (FRO2-like and IRT1-like), were over-expressed in roots of Fe-sufficient G. max and in Fe-deficient M. truncatula. VIT1-like, YSL1-like and ferritin presented higher expression levels in Fe-sufficient shoots and roots, whereas NRAMP3-like and GCN2-like showed higher expression values in Fe-deficiency.
- Effect of tris(3-hydroxy-4-pyridinonate) iron(III) complexes on iron uptake and storage in soybean (Glycine max L.)Publication . Santos, Carla S.; Carvalho, Susana M.P.; Leite, Andreia; Moniz, Tânia; Roriz, Mariana; Rangel, António O. S. S.; Rangel, Maria; Vasconcelos, Marta W.Iron deficiency chlorosis (IDC) is a serious environmental problem affecting the growth of several crops in the world. The application of synthetic Fe(III) chelates is still one of the most common measures to correct IDC and the search for more effective Fe chelates remains an important issue. Herein, we propose a tris(3-hydroxy-4-pyridinonate) iron(III) complex, Fe(mpp)3, as an IDC corrector. Different morphological, biochemical and molecular parameters were assessed as a first step towards understanding its mode of action, compared with that of the commercial fertilizer FeEDDHA. Plants treated with the pyridinone iron(III) complexes were significantly greener and had increased biomass. The total Fe content was measured using ICP-OES and plants treated with pyridinone complexes accumulated about 50% more Fe than those treated with the commercial chelate. In particular, plants supplied with compound Fe(mpp)3 were able to translocate iron from the roots to the shoots and did not elicit the expression of the Fe-stress related genes FRO2 and IRT1. These results suggest that 3,4-HPO iron(III) chelates could be a potential new class of plant fertilizing agents.
- Transcriptomic analysis of iron deficiency related genes in the legumesPublication . Santos, Carla S.; Silva, Ana I.; Serrão, Inês; Carvalho, Ana L.; Vasconcelos, Marta W.Among the mineral elements required by humans, iron (Fe) is the most common cause of nutritional deficiencies, particularly anaemia. Legume plants are extremely important in the world's diet and they are major sources of mineral nutrients. However, when these plant foods are grown in calcareous soil, their production is severely affected by Fe deficiency chlorosis (IDC), and when less Fe is available for absorption, less amount of this element will be available for accumulation in the edible plant parts. As Fe plays critical roles in photosynthesis and respiration, when lacking this element, plants develop chlorosis and their growth is drastically reduced. IDC morphological symptoms were monitored in soybean (Glycine max), common bean (Phaseolus vulgaris) and the model crop barrel medic (Medicago truncatula). When compared to the other two legumes, G. max presented lower Fe-reduction rates and severe chlorosis, associated with lower SPAD values. Transcriptome analysis was performed in roots of the three species when grown in Fe deficiency and Fe sufficiency, and 114,723 annotated genes were obtained for all samples. Four IDC-related genes were up-regulated in common by the three species and can be considered key players involved in the IDC response, namely, metal ligands, transferases, zinc ion binding and metal ion binding genes. With regards to the genes most highly expressed under iron deficiency individually by each species, we found that the most highly expressed genes were a defensin in P. vulgaris, a phosphatase in M. truncatula and a zinc ion binding gene in G. max.