![]() ![]() Although most of the members of the MGT family have Mg transport activity as proven by functional complementation with yeast and bacteria mutants, their physiological roles in plants are largely different. MGT is the best-studied gene family of Mg 2+ transporter in plants ( Gebert et al., 2009 Saito et al., 2013). A CNGC family protein, AtCNGC10, has been indicated to mediate Mg 2+ influx, particularly in the root meristem and distal elongation zones ( Guo et al., 2010). OsHKT2 4 has the function of low-affinity Mg 2+ transporter in rice ( Zhang et al., 2017). MHX is a unique vacuolar Mg 2+ transporter in Arabidopsis ( Shaul et al., 1999). MHX (Mg 2+/H + Exchanger), HKT (High-Affinity K + Transport), CNGC (Cyclic Nucleotide-Gated Channel) and MGT (Magnesium Transporter) have been identified as Mg 2+ transporters in plants ( Shaul et al., 1999 Gebert et al., 2009 Tang and Luan, 2017 Zhang et al., 2017). In view of the unique chemical property and biological significance of Mg 2+, more and more studies have been conducted to gain understanding of the genetic and molecular mechanism of Mg 2+ uptake, translocation and distribution in plants ( Li et al., 2008 Hermans et al., 2013). ![]() Therefore, crop production problems caused by magnesium deficiency have gradually become important issues in agriculture. With the increase of crop yield and multi-cropping, Mg consumption leads to the lack of Mg in soil ( Rosanoff, 2013). Additionally, excessive application of high rates of K + andįertilizers antagonistically interfere with plant Mg uptake, thus enhances the risk of Mg deficiency ( Gransee and Führs, 2013). This unique chemical property makes Mg 2+ bind weakly to negative charged soil colloids and root cell walls, which leads to the loss of the exchangeable Mg easily from soil ( Aitken et al., 1999 Hermans et al., 2004). The only effective form of Mg absorption by plants is Mg 2+, which has the smallest ionic radius but the largest hydrated ionic radius in cations ( Maguire and Cowan, 2002). Lack of magnesium reduces the rate of photosynthesis and disrupts the distribution of carbohydrates from source to sink in plants, while inhibiting the growth of plant organs, eventually leading to a significant decrease in crop quality and productivity ( Aitken et al., 1999 Rissler et al., 2002 Verbruggen and Hermans, 2013). Mg is also a necessary element in carbohydrate partitioning ( Cakmak et al., 1994 Cakmak, 2013). The ionic form of magnesium (Mg 2+) is the most abundant divalent cation in plant cells, and its most prominent role may be its function as a central atom of chloroplast molecules in photosynthesis ( Rissler et al., 2002 Cakmak, 2013). Overexpression of LOC_Os03g04360 can significantly increase the Mg 2+ concentration in rice seedlings, especially under the condition of low Mg 2+ supply.Īs a key macronutrient, magnesium (Mg) plays an important role in plant growth, development and reproductive success ( Verbruggen and Hermans, 2013). ![]() Analysis of candidate genes in the region of qSMg3 and qTrMg3 through qRT-PCR, complementation assay in the yeast Mg 2+ transport-defective mutant CM66, and sequence analysis of the parental lines suggested that LOC_Os03g04360 may play important roles in Mg 2+ uptake, translocation and accumulation in rice. qSMg3 and qTrMg3 might be the same, since they are very close to each other on chromosome 3. Two QTLs ( qTrMg3 and qTrMg8) were found to affect the translocation of Mg 2+ from the roots to the shoots, and explained 10.91% and 9.63% of phenotypic variation. Three QTLs ( qSMg3, qSMg7 and qSMg10) were detected for the shoot Mg 2+ concentration, which explained 4.30-5.46% of the phenotypic variation. The Mg 2+ transporter gene, OsMGT1, was within the region of qRMg1. Four QTLs ( qRMg1, qRMg2, qRMg7 and qRMg8) were detected for the root Mg 2+ concentration, which explained 11.45-13.08% of the phenotypic variation. We used a multi-parent advanced generation inter-cross (MAGIC) population constructed using four parental lines and genotyped by a 55 K rice SNP array for association analysis to locate QTLs related to Mg 2+ uptake and translocation in rice at the seedling stage. Rice is an important food crop in the world, but there are few studies on the uptake and translocation of Mg 2+ in rice. Magnesium (Mg) is an essential element for plant growth and development. ![]()
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