The Conservation of VIT1-Dependent Iron Distribution in Seeds

One third of people suffer from anemia, with iron (Fe) deficiency being the most common reason. The human diet includes seeds of staple crops, which contain Fe that is poorly bioavailable. One reason for low bioavailability is that these seeds store Fe in cellular compartments that also contain antinutrients, such as phytate. Thus, several studies have focused on decreasing phytate concentrations. In theory, as an alternative approach, Fe reserves might be directed to cellular compartments that are free of phytate, such as plastids. However, it is not known if seed plastid can represent a major Fe storage compartment in nature. To discover distinct types of Fe storage in nature, we investigated metal localizations in the seeds of more than twenty species using histochemical or X-ray based techniques. Results showed that in Rosids, the largest clade of eudicots, Fe reserves were primarily confined to the embryo of the seeds. Furthermore, inside the embryos, Fe accumulated specifically in the endodermal cell layer, a well-known feature that is mediated by VACUOLAR IRON TRANSPORTER1 (VIT1) in model plant Arabidopsis thaliana. In rice, Fe enrichment is lost around the provasculature in the mutants of VIT1 orthologs. Finally, in Carica papaya, Fe accumulated in numerous organelles resembling plastids; however, these organelles accumulated reserve proteins but not ferritin, failing to prove to be plastids. By investigating Fe distribution in distinct plant lineages, this study failed to discover distinct Fe storage patterns that can be useful for biofortification. However, it revealed Fe enrichment is widely conserved in the endodermal cell layer in a VIT1-dependent manner in the plant kingdom

Genome-wide analysis of gene expression profiling revealed that COP9 signalosome is essential for correct expression of Fe homeostasis genes in Arabidopsis

In plant cells, either excess or insufficient iron (Fe) concentration triggers stress responses, therefore it is strictly controlled. Proteasome-mediated degradation through ubiquitination of Fe homeostasis proteins has just become the focus of research in recent years. Deactivating ubiquitin ligases, COP9 signalosome has a central importance in the translational control of various stress responses. The aim of the study was to investigate COP9 signalosome in Fe deficiency response of Strategy I plants. In silico analysis of a set of Fe-deficiency-responsive genes was conducted against the transcriptome of Arabidopsis csn mutant lines using Genevestigator software. Induced and suppressed genes were clustered in a hierarchical way and gene ontology enrichment categories were identified. In wild-type Arabidopsis, CSN genes did not respond to iron deficiency. In csn mutant lines, under Fe-sufficient conditions, hundreds of Fe-deficiency-responsive genes were misregulated. Among the ones previously characterized for their physiological roles under Fe deficiency IRT1, NAS4, BTS, NRAMP1 were down-regulated while AHA2, MTP8, FRD3 were up-regulated. Unexpectedly, from those which were regulated in opposite ways, some had been repeatedly shown to be tightly co-regulated by the same transcription factor, FIT. Two proteins from DELLA family, which were reported to interact with FIT to repress its downstream, were found to be strikingly repressed in csn mutants. Overall, the study underlined that the absence of a functional CSN greatly impacted the regulation of Fe homeostasis-related genes, in a manner which cannot be explained simply by the induction of the master transcription factor, FIT. Correct expression of Fe deficiency-responsive genes requires an intact COP9 signalosome in Arabidopsis

Evaluation of CaCO3 clogging in emitters with magnetized saline waters

High water application uniformity is essential for an effective irrigation. Clogging of emitters in drip irrigation systems is one of the most important factors decreasing uniformity. In this study, the possible effect of magnetization of water on chemical clogging of dripline emitters was investigated. Separate experiments were conducted with three different saline waters (W-1: 0.314 dS m(-1), W-2: 0.665 dS m(-1), W-3: 0.937 dS m(-1)) having a high pH and a positive Langelier saturation index (LSI). Discharge rates, electrical conductivity (EC) and pH's of discharge water from emitters in driplines were measured. Uniformity of driplines was evaluated by using the statistical uniformity coefficient (U-c) and the emission uniformity coefficient (E-u). The pH and EC values of discharge water from emitters in driplines were found to be slightly lower when operated with magnetized water. However, discharge rates under non-magnetized water were lower than those of magnetized water. Magnetic effect was observed to be decreased as the water salinity increased. The U-c and the E-u values indicated that when the medium saline water was magnetized before its release into the system, a better uniformity due to a lower emitter clogging rate can be achieved. When higher saline water was magnetized, lower U-c and the E-u values were observed

Genome-wide exploration of metal tolerance protein (MTP) genes in common wheat (Triticum aestivum): insights into metal homeostasis and biofortification

Metal transport process in plants is a determinant of quality and quantity of the harvest. Although it is among the most important of staple crops, knowledge about genes that encode for membrane-bound metal transporters is scarce in wheat. Metal tolerance proteins (MTPs) are involved in trace metal homeostasis at the sub-cellular level, usually by providing metal efflux out of the cytosol. Here, by using various bioinformatics approaches, genes that encode for MTPs in the hexaploid wheat genome (Triticum aestivum, abbreviated as Ta) were identified and characterized. Based on the comparison with known rice MTPs, the wheat genome contained 20 MTP sequences; named as TaMTP1-8A, B and D. All TaMTPs contained a cation diffusion facilitator (CDF) family domain and most members harbored a zinc transporter dimerization domain. Based on motif, phylogeny and alignment analysis, A, B and D genomes of TaMTP3-7 sequences demonstrated higher homology compared to TaMTP1, 2 and 8. With reference to their rice orthologs, TaMTP1s and TaMTP8s belonged to Zn-CDFs, TaMTP2s to Fe/Zn-CDFs and TaMTP3-7s to Mn-CDFs. Upstream regions of TaMTP genes included diverse cis-regulatory motifs, indicating regulation by developmental stage, tissue type and stresses. A scan of the coding sequences of 20 TaMTPs against published miRNAs predicted a total of 14 potential miRNAs, mainly targeting the members of most diverged groups. Expression analysis showed that several TaMTPs were temporally and spatially regulated during the developmental time-course. In grains, MTPs were preferentially expressed in the aleurone layer, which is known as a reservoir for high concentrations of iron and zinc. The work identified and characterized metal tolerance proteins in common wheat and revealed a potential involvement of MTPs in providing a sink for trace element storage in wheat grains

Microbial application with gypsum increases the saturated hydraulic conductivity of saline-sodic soils

Microbial application for the amelioration of sodic and saline-sodic soils may reduce the economic and environmental costs of chemical amendments. The effect of microbial application on saturated hydraulic conductivities of four different saline-sodic soils which were being ameliorated with gypsum was studied. Suspensions of three fungal isolates (Aspergillus spp. FS 9, 11 and Alternaria spp. FS 8) and two bacterial strains (Bacillus subtilis OSU 142 and Bacillus megaterium M3) at 10(4) spore/ml and 10(9) CFU/ml, respectively, were mixed with leaching water and applied to the soil columns. The measured saturated hydraulic conductivities of soil columns after the treatment indicated that saturated hydraulic conductivity of saline-sodic soils increased significantly (P < 0.01) by application of the microorganisms. Average increase for all soils was 68%. The data suggest that microorganisms tested in the present study may have potential to help improve water movement through saline-sodic soils