Abstract
Manganese (Mn) is an essential micronutrient; however, few genes required for growth under low-Mn conditions have been identified. In this study, we isolated Arabidopsis thaliana mutants sensitive to low-Mn conditions from ethyl methanesulfonate-mutagenized seeds. Among them, we identified the causal genes of two mutants. One mutant (35-34) exhibited a short root phenotype and low Mn concentration in the shoots. The other mutant (30-11) exhibited a small shoot phenotype with Mn concentrations similar to the control. Genetic mapping, allelism tests, and gene complementation tests identified the causal genes as At1g80830 (NRAMP1) for 35-34 and At5g18480 (PGSIP6) for 30-11. NRAMP1 was previously reported to be essential for Mn uptake under low-Mn conditions, thus validating our screening method. PGSIP6 encodes inositol phosphorylceramide glucuronosyltransferase, which is involved in glycosyl inositol phosphorylceramide sphingolipid glycosylation. PGSIP6-green fluorescent protein was localized to the Golgi apparatus, which is consistent with its function in the glycosylation of sphingolipids. Our screening identified a novel gene required for low-Mn tolerance, and we also provide new insights towards understanding the physiological function of PGSIP6.
Highlights
Manganese (Mn) is an essential micronutrient for all known organisms, and is the second most abundant transition element constituting the Earth’s crust (Yang et al, 2008)
We obtained eight mutant lines (Supplementary Fig. S1 at JXB online) and from among these, we focused on two mutants, 35-34 and 30-11
We focused on two of them, Mn concentration-dependent phenotypes of pgsip6-1
Summary
Manganese (Mn) is an essential micronutrient for all known organisms, and is the second most abundant transition element constituting the Earth’s crust (Yang et al, 2008). The dominant form of Mn in aerated soils is the tetravalent state, but only the form Mn (Mn2+) is the available for uptake by plants. Soil contains a large amount of Mn, the quantity that can be used by organisms is quite low (Kabata-Pendias, 2011). Mn deficiency a physiological disorder that is widely observed in agriculture. Mn deficiency often occurs in alkaline or calcareous soils due to the low bioavailability and immobilization of Mn2+ (Marschner, 1995). Typical Mn-deficiency symptoms include diffused interveinal chlorosis in younger leaves due to the low phloem mobility of Mn2+ from old to young leaves (Marschner, 1995; Schmidt et al, 2016). It has been reported that some species become more
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