Biology subjects

Vogel-Mikus, K.

Publications and source records attributed to Vogel-Mikus, K..

3 recordsLinked to original sources

bioRxiv2024

Element partitioning, element localisation and transcriptome responses of date palms exposed to NaCl

Date palm (Phoenix dactylifera L.) is an economically important fruit crop in many (semi)arid regions. Large intra-species variation in susceptibility to NaCl has been reported. Controlled experiments were conducted to evaluate sodium (Na) and chlorine (Cl) partitioning in two-year old plants of six date palm varieties and to determine tissue location of Na and Cl and transcriptome responses to NaCl of two varieties. The largest Na concentrations were found in secondary roots, especially under NaCl treatment. By contrast, only small differences in within-plant partitioning of Cl were observed with less differences between varieties than for Na. Variety Sultana had the largest Na translocation factor. The variety Khalas exhibited better restriction of Na mobility, which may be a consequence of Na hotspots in roots, presumably immobilising Na in roots, which were absent in Sultana. In the root, shoot base and lower part of leaves, Cl accumulated in fibre bands and sclerenchyma sheaths of vascular bundles. RNAseq analysis revealed that Sultana and Khalas respond very differently to NaCl: Khalas modified expression of NaCl-specific genes in both roots and leaves, while Sultana responded manly in leaves. Gene ontology analysis showed that the expression changes for genes linked with photosynthesis and carbohydrate metabolism predominated as a response to NaCl. In Khalas, differentially expressed genes encoding for metal transporters and those reported to be involved in heat, salt and osmotic stress response were found. Large variability in Na and Cl accumulation in different date palm varieties may have practical agronomical consequences.

plant biology↗

bioRxiv2023

Improved sample preparation for fruits allowed histochemistry and X-ray microscopy to reveal conserved iron hotspots

Global fruit production suffers from pre- and post- harvest losses, part of which are related to metal deficiencies. Despite fruits being one of the most widely consumed plant parts, the spatial distribution of metals and their physiological significance remained largely unexplored. In this study, we investigated metal accumulation sites in fruits of 28 major crops by using X-ray and histochemical-based techniques. We found that calcium accumulated in the outermost hardened tissues, potassium in sugar accumulating fleshy tissues, and iron (Fe) in vascular tissues in a conserved manner. Vascular Fe pattern traced to the seed revealed an Fe reservoir at the fruit-seed juncture in tomato, which persisted in the seeds chalazal region upon dispersal. To determine the physiological function of these stored reserves, we manipulated Fe bioavailability. Two opposely acting chelators, desferoxamine, an Fe immobilizer, delayed germination, while nicotianamine, a mobilizer, accelerated it in wild-type plants but not in mutants with low chalazal Fe. Additionally, external Fe supplementation also increased germination speed in a dose-dependent manner. Collectively, these findings demonstrate that fruit vasculature serves as a critical delivery system to establish seed Fe pools, which are determinants of seed germination speed. This study provides the first comprehensive atlas of metal hotspots in fleshy fruits and links anatomical distribution to a defined physiological mechanism in seed biology.

plant biology↗

bioRxiv2018

VIT1-dependent Fe distribution in seeds is conserved in dicots

One third of the people suffer from iron (Fe) Fe deficiency. An underlying factor for this malnutrition is insufficient Fe intake from the diet. A major part of the human diet includes seeds of staple crops, which contain Fe that is poorly bioavailable. One reason for the low bioavailability is these seeds store Fe in cellular compartments that also contain antinutrients, such as phytate. Thus, several studies focused on decreasing phytate concentrations. As an alternative approach to increase bioavailable Fe, Fe reserves might be directed to cellular compartments such as plastids that are free of phytate. Previous studies indicated that Fe reserves can be relocalized inside the seed to the desired compartment by genetic modification, provided that a suitable iron transporter protein is used. However, to the best of our knowledge, a Fe transporter localizing to plastids have not been identified in seeds to date. To discover novel Fe transporters, we screened Fe patterns in seeds of distinct plant lineages, hypothesizing Fe hyperaccumulating sites would indicate Fe transporter presence. To this end, metal localizations in seeds of more than twenty species were investigated using histochemical or X-ray based techniques. Results showed that in Rosids, the largest clade of eudicots, Fe reserves were primarily confined in the embryo part of the seeds. Furthermore, inside the embryos, Fe was enriched in the endodermal cell layer, a well-known feature that is mediated by vacuolar Fe transporter, VIT1 in model plant Arabidopsis thaliana. This enrichment was well conserved in and beyond Rosid species. Finally, a few seeds showed novel Fe patterns, including Carica papaya which concentrated large Fe reserves exclusively in plastids called amyloplasts. Generally, Fe stored in amyloplast is considered bioavailable. Taken together, this study suggests dicot seeds store Fe mainly in the embryo, with a VIT1-dependent enrichment in its endodermal cell layer and indicate Carica papaya possess a strong Fe transporter at the plastid membrane. Once it is identified that might be useful in biofortification, as a novel tool to shift Fe to compartments where it is more bioavailable.

plant biology↗