N7-0077 — Final report
1.
Magnesium and calcium over-accumulate in the leaves of a schengen3 mutant of Brassica rapa

Magnesium (Mg) and calcium (Ca) are essential nutrients for plants and animals. Human deficiencies of these elements are not uncommon. In the study the elemental composition of a mutagenized population of Brassica rapa was measured and a line carrying a recessive mutation that led to an elevated accumulation of Mg in most tissues, as well as elevated levels of Ca was identified. The mutation was mapped to a region corresponding to the SHENGEN3 (SGN3) gene, which was previously characterized in Arabidopsis as contributing to the formation of the impermeable Casparian strip barrier at the root endodermis, with sgn3 mutants having a “leaky” endodermis with increased Mg and Ca accumulation in leaves. Localisation of Mg and Ca and other essential elements was determined in leaves and seeds of these plants. These finding can be used to develop non-GMO foods with enhanced levels of Mg and Ca.

COBISS.SI-ID: 59167235
2.
Contrasting allocation of magnesium, calcium and manganese in leaves of tea (Camellia sinensis (L.) Kuntze) plants may explain their different extraction efficiency into tea

During tea preparation mineral elements are extracted from the dried leaves of tea (Camellia sinensis (L.) Kuntze) plants into the solution. Micro-particle induced X-ray emission was employed to investigate the spatial distribution of magnesium (Mg), calcium (Ca) and manganese (Mn) in the young and old leaves of tea plants grown in the absence and presence of aluminium (Al) in the substrate. Results revealed that in tea leaves the largest concentrations of Mg occurred in the epidermis, of Ca in oxalate crystals and of Mn in epidermis and oxalate crystals; there was a leaf-age effect on tissue-specific concentrations of Mg, Ca and Mn with all tissues of old leaves containing larger concentrations of Mg, Ca and Mn than young leaves; supplementation of substrate with Al reduced concentrations of Mg, Ca and Mn in the old leaves, and a link between the distribution of Mg, Ca and Mn in the tea leaves with the extraction efficiencies of these elements into the tea was possible. We conclude that old leaves of tea plants cultivated under conditions of low Al availability will have the largest concentrations of Mg, Ca and Mn and may represent most acceptable ingredient for the preparation of tea.

COBISS.SI-ID: 32880423
3.
Cadmium associates with oxalate in calcium oxalate crystals and competes with calcium for translocation to stems in the cadmium bioindicator Gomphrena claussenii

Cadmium (Cd) was shown to co-localise with calcium (Ca) in oxalate crystals in stems and leaves of Cd tolerant Gomphrena claussenii, but Cd binding remained unresolved. Using synchrotron radiation X-ray absorption near edge spectroscopy we demonstrate that in oxalate crystals of hydroponically grown G. claussenii the vast majority of Cd is bound to oxygen ligands in oxalate crystal ()88%; Cd-O-C coordination) and the remaining Cd is bound to sulphur ligands (Cd-S-C coordination). Cadmium binding to oxalate does not depend on the amount of Ca supplied or from which organs the crystals originate (stems and mature leaves). By contrast, roots contain no oxalate crystals and therein Cd is bound predominantly by S ligands. The potential to remove Cd by extraction of Cd-rich oxalate crystals from plant material should be tested in phytextraction or phytomining strategies.

COBISS.SI-ID: 4794703
4.
Calcium redistribution contributes to the hard-to-cook phenotype and increases PHA-L lectin thermal stability in common bean low phytic acid 1 mutant seeds

Seed phytic acid reduces mineral bioavailability by chelating minerals. Consumption of common bean seeds with the low phytic acid 1 (lpa1) mutation improved iron status in human trials but caused adverse gastrointestinal effects, presumably due to increased stability of lectin phytohemagglutinin L (PHA-L) compared to the wild type (wt). A hard-to-cook (HTC) defect observed in lpa1 seeds intensified this problem. We quantified the HTC phenotype of lpa1 common beans with three genetic backgrounds. The HTC phenotype in the lpa1 black bean line correlated with the redistribution of calcium particularly in the cell walls, providing support for the “phytase-phytate-pectin” theory of the HTC mechanism. Furthermore, the excess of free cations in the lpa1 mutation in combination with different PHA alleles affected the stability of PHA-L lectin. The results of this work have produced important knowledge on how, unexpectedly, the lpa1 mutation may affect important cooking and nutritional traits, which must be taken into account in future breeding strategies.

COBISS.SI-ID: 33286183