Mg Contents In Roots Research Articles

Mutations in RZF1, a zinc-finger protein, reduce magnesium uptake in roots and translocation to shoots in rice.

Magnesium (Mg) homeostasis is critical for maintaining many biological processes, but little information is available to comprehend the molecular mechanisms regulating Mg concentration in rice (Oryza sativa). To make up for the lack of information, we aimed to identify mutants defective in Mg homeostasis through a forward genetic approach. As a result of the screening of 2,825 M2 seedlings mutated by ion-beam irradiation, we found a rice mutant that showed reduced Mg content in leaves and slightly increased Mg content in roots. Radiotracer 28Mg experiments showed that this mutant, named low-magnesium content 1 (LMGC1), has decreased Mg2+ influx in the root and Mg2+ translocation from root to shoot. Consequently, LMGC1 is sensitive to the low Mg condition and prone to develop chlorosis in the young mature leaf. The MutMap method identified a 7.4-kbp deletion in the LMGC1 genome leading to a loss of two genes. Genome editing using CRISPR-Cas9 further revealed that one of the two lost genes, a gene belonging to the RanBP2-type zinc-finger family that we named RanBP2-TYPE ZINC FINGER1 (OsRZF1), was the causal gene of the low Mg phenotype. OsRZF1 is a nuclear protein and may have a fundamental role in maintaining Mg homeostasis in rice plants.

Excess Copper-Induced Changes in Antioxidative Enzyme Activity, Mineral Nutrient Uptake and Translocation in Sugarcane Seedlings.

Sugarcane is a potential species for use in heavy metal remediation. To analyze the effect of excess copper on sugarcane, the biomass, mineral nutrient content and activities of antioxidative enzymes were measured under copper stress. The results revealed that the biomass of roots and shoots significantly decreased with increasing copper concentration in solution. Most copper accumulated in the roots, and the translocation factor of copper decreased with an increase in copper stress. The MDA content in sugarcane roots notably increased under copper stress. The POD activity in sugarcane roots increased, and CAT activity decreased under copper stress. The Zn, Fe and Mn contents in shoots increased significantly under 200μmolL-1 Cu2+ treatments. The Zn and Mg contents in roots notably decreased under copper stress, while the Zn and Mg translocation factors increased. These results indicated that the increase in POD activity and the modification of mineral nutrient uptake and transfer might play an important role in reducing the detrimental effects of excess copper.

Effects of Biochar on Ca, Mg and B Uptake of Peach Seedlings

A pot experiment was conducted to study the effects of different biochar types [addition of rape straw biochar (RB), addition of paddy straw biochar (PB), addition of wheat straw biochar (WB) and addition of corn straw biochar (MB)] on the absorption of Ca, Mg and B in peach seedlings. The result showed that compared to the control, all treatments added with biochar significantly decreased the Ca content in roots in peach seedlings. The Ca content in stems and leaves under the treatment of RB and PB in peach seedlings was higher than the control. The Mg content in roots and stems under the treatment of PB in peach seedlings was higher than the control. The Mg content in leaves in peach seedlings of all treatments added with biochar was lower than the control. The B content in roots, stems and leaves under the treatment of PB, WB and MB in peach seedlings was higher than the control and the B content under the treatment of PB was at a higher level. Therefore, the treatment of PB was beneficial to the absorption of trace elements in peach seedlings.

Effects of conifer wood biochar as a substrate component on ornamental performance, photosynthetic activity, and mineral composition of potted Rosa rugosa

ABSTRACTA greenhouse experiment was conducted to assess the performance of biochar obtained from pyrolysis of conifer wood as a substrate component for growing potted Rosa rugosa plants. Rose plants were grown with different mixtures of sphagnum peat and biochar (100% peat, 75% peat–25% biochar, 50% peat–50% biochar, 25% peat–75% biochar; v:v). Increasing the biochar content from 25% to 75% increased the air content, bulk density, electrical conductivity, and K and Na concentration in the substrates. The addition of 25% biochar to the substrate showed promising potential for R. rugosa when compared with 100% peat given the similar growth performance, water-use efficiency, and ornamental quality (number of flowers and leaf colour). The Ca and Na concentrations in leaves and roots as well as the Mg content in roots increased as the biochar percentage in the substrate increased, whereas an opposite trend was observed for P and K concentrations. The best performance and ornamental quality of R. rugosa grown with 100% peat and 75% peat–25% biochar compared with 50 and 75% biochar treatments were attributed to a higher degree of photosynthesis, Soil Plant Analysis Development index, and pigment content. Overall, adding 25% of conifer wood biochar as a substrate component could be applied for economic purposes without detrimental effects on the yield and quality of potted roses.

Response of mycorrhizal hybrid tomato cultivars under saline stress

The response of hybrid tomato cultivars (Solanum lycopersicumL. Cvs. TSS7 and TCAV10) inoculated with arbuscular mycorrhizal fungi Claroideoglomus etunicatum(AMF-1) and Funneliformis mosseae(AMF-2) under 2% saline stress was evaluated with regard to growth, yield, quality, nutrient acquisition, AMF colonization, relative permeability and soil properties in two potted plant experiments. Inoculation with AMF-2 caused a significant increase (~30%) in the fruit yield of TCAV10, particularly under saline stress. The highest tomato juice extraction ratio was achieved for TCAV10 treated with AMF-2. Under saline stress, TCAV10 inoculated with AMF-2 demonstrated significantly enhanced N, P, K and Ca content in fruits; N, K and Mg content in roots; and N, P and Ca content in shoots. Fruits of TSS7 and TCAV10 grown under saline stress coupled with AMF-2 treatment showed a significant decrease in Na content (23.6 and 31.1%, respectively) as compared with fruits of non-inoculated hybrid cultivars grown under saline stress. Residual Na in soil, AMF-2 colonization ratios and relative permeability were higher in TCAV10 inoculated with AMF-2 under saline condition compared with the non-inoculated treatments. TCAV10 inoculated with AMF-2 achieved higher fruit yield, quality and nutrient acquisition compared with the non-inoculated TCAV10. The results of this study are important for the selection of appropriate cultivars and microbial species for sustaining yield and quality under saline stress.

Relationships between root activity and N, P, K, Ca, and Mg contents in roots of field crops

Based on the previous paper (Osaki et al. 1995, Soil Sci. Plant Nutr., 41, 635-647), crops were classified by root characteristics for nitrogen uptake as follows: Group I (small root dry weight (RW) and high specific absorption rate of nitrogen (SARN)): legumes, potato, and beet; group II (large RW and low SARN): cereals; and group III (large RW and high SARN): sunflower. In the roots of field crops subjected to various treatments in a field of Hokkaido University, the nitrogen, calcium, and magnesium contents in roots were relatively higher in group I than in groups II and III. Potassium content in roots was high in maize and sunflower. Phosphorus content in roots in groups I and II increased linearly with the increase of the nitrogen content, and the contents of both minerals were higher in group II than in group I. However, the phosphorus content in group III remained constant or increased slightly with the increase of the nitrogen content. Potassium content in roots in groups I and II did not change with the increase of the nitrogen content up to a value of about 20 mg g−1 then it increased slightly with the increase of the nitrogen content above a value of about 20 mg g−1, especially in group I. Potassium content in roots in group III was constant regardless of nitrogen content. Calcium and magnesium contents were not related to the nitrogen content in groups I and II, but increased with the increase of the nitrogen content in group III. SARN increased exponentially with the increase of the nitrogen content in the roots of groups I and II. In group I, the values of SARN were generally higher than in group II for a similar nitrogen content, while in group III, SARN increased linearly with the increase of nitrogen content in roots. Consequently, it appears that nitrogen and phosphorus nutrition in roots is very important for the maintenance of root activity (SARN).