Solubility of iron is limited in calcareous soil although it is one of the most common elements in earth’s crust. Therefore, plants growing in this kind of soil are constantly exposed to the stress of iron deficiency. When untreated, iron deficiency restricts agricultural production because one third of the agricultural land in the world is made up of this type of soil. Different iron fertilizers are used in the treatment of iron deficiency observed in plants. However, the use of these fertilizers increases production costs. In order to reduce the cost, plants must be able to use the most effective way to extract iron from the soil. For this reason, it is necessary to first examine how the plants take iron into roots from the soil. It has been discovered that during the last three decades, different plant groups used three different iron uptake mechanisms. The purpose of this review is to talk about the transporters responsible for the uptake of iron into the root, and the current developments about these transporters.

Salinity stress is one of the most important and common abiotic stress factors that cause significant physiological and metabolic changes in plants, negatively affecting plant growth and development, and causing decrease in product quality and quantity. The elucidation of the molecular control mechanisms associated with salt stress tolerance is based on the activation and /or inactivation of various stress-related genes. Salt Overly Sensitive (SOS) tolerance mechanism under salt stress is of great importance in terms of salt tolerance of the plants. Although this mechanism has been studied for many years, the physiological changes that the plants give as a result of mutation of the genes in the pathway under different levels of sodium chloride (NaCl) during development have not been examined comparatively. In this study, we found that the Arabidopsis thaliana sos1-1 mutant plant showed sensitivity to 10 mM NaCl while the sos3-1 and hkt1-1 mutants showed tolerance. The sos1-1, sos3-1 and hkt1-1 mutants showed increasing sensitivity when NaCl was applied beyon 50 mM of concentration. In addition, plants did not show significant sensitivity for 1 day of stress application, while significant effects were observed in plant root length when exposed to salinity for 3 to 4 days. Col-0, hkt1-1 and sos3-1 roots treated with low levels of NaCl for a short term were positively affected in length. In the light of these results, the amount and duration of salt stress is very critical in Arabidopsis thaliana's responses to the stress and determination of molecular tolerance pathways.

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Iron (Fe) is an important trace mineral for plant development, and plants grown in Fe deficiency experience yield losses due to the leaf chlorosis. In addition to agronomic measures that can be taken to minimize these losses, new plant genotypes can be developed effectively through genetic engineering. While dicots such as Arabidopsis thaliana use a reduction-based strategy to uptake high amounts of iron from the rhizosphere, the chelation strategy has evolved in Gramineous plants including barley (Hordeum vulgare). In this study, barley NICOTIANAMINE SYNTHASE1 (HvNAS1) gene, which is responsible for the production of nicotianamine that can complex with iron, was cloned and expressed at a constitutive high level in Arabidopsis plants. The expression levels of Arabidopsis genes encoding for the proteins involved in iron uptake increased together with HvNAS1 in the T3 Arabidopsis plants. Moreover, the root lengths, root and stem fresh weights, ferric chelate reductase enzyme activities of the plants also increased in the transgenic Arabidopsis plants under Fe deficiency. In addition, significant increases in iron and zinc levels were determined in the roots and shoots of transgenic Arabidopsis plants. As a result, transgenic Arabidopsis plants overexpressing the barley HvNAS1 gene can take up more iron from the rhizosphere and carry this iron to the shoots. This study demonstrates the power of genetic engineering to develop Arabidopsis plants overexpressing the HvNAS1 gene and therefore tolerate iron deficiency.

Temel mikro-besin elementi demir (Fe) bitkide önemli rolleri bulunan birçok metalloproteinin aktif bölgesinde kofaktör olarak yer alır. Öte yandan aşırı reaktif olduğundan, hücre içerisinde fazla birikimi reaktif oksijen türlerinin üretimini tetikleyerek hücre ölümlerine neden olur. Dolayısıyla hücre içerisindeki demir homeostazı bitki gelişimi için çok önemlidir. Bitkiler demiri kök içerisine aldıktan sonra hücre içi kompartmanlara dağıtımını yaparlar. Hücre içi demir taşınımı ve dolayısıyla hücresel demir homeostazı farklı membran protein ailelerinin senkronize kontrolü sayesinde yürütülmektedir. Bu membran proteinlerinin demir eksikliği altında ifade seviyelerinin arttığı keşfedilmiştir. Bu taşıyıcıların görev ve regülasyonlarının irdelenmesi bitkilerdeki demir alım ve dağıtım mekanizmalarının anlaşılması açısından çok önemlidir. Bu yüzden bu derlemede hücre içerisine alınan demirin organellere dağıtımından sorumlu taşıyıcılar ile bu taşıyıcılar hakkındaki güncel gelişmelerden bahsedilmektedir. Subcellular Iron Localization Mechanisms in Plants A R T I C L E I N F O A B S T R A C T Review ArticleReceived 13 May 2017 Accepted 11 October 2017The basic micro-nutrient element iron (Fe) is present as a cofactor in the active sites of many metalloproteins with important roles in the plant. On the other hand, since it is excessively reactive, excess accumulation in the cell triggers the production of reactive oxygen species, leading to cell death. Therefore, iron homeostasis in the cell is very important for plant growth. Once uptake into the roots, iron is distributed to the subcellular compartments. Subcellular iron transport and hence cellular iron homeostasis is carried out through synchronous control of different membrane protein families. It has been discovered that expression levels of these membrane proteins increase under iron deficiency. Examination of the tasks and regulations of these carriers is very important in terms of understanding the iron intake and distribution mechanisms in plants. Therefore, in this review, the transporters responsible for the uptake of iron into the cell and its subcellular distribution between organelles will be discussed with an emphasis on the current developments about these transporters.