Os07g0257200

The rice Os07g0257200 was reported as OsNRAMP5 three times by Japanese researchers in 2012^[1]^[2]^[3].

Annotated Information

Figure 1. Wild-type lines VS. NRAMP5 knock-out lines (from reference^[2]).

The plant Natural resistance associated macrophage protein (NRAMP) gene family play an important role in the transportation of metal ions and maintaining their intracellular homeostasis^[4]. As a member of rice NRAMP gene family, OsNRAMP5 is a major transporter responsible for Mn uptake and Cd in the roots.

It can participate in the major route for Cd entering the root cells from the external environment in rice^[1]^[2]. The research by Yasuhiro Ishimaru also pointed out that OsNRAMP5 would function as a Fe and Mn transporter during flowering and seed development^[3].

The OsNramp5 Knock-out Line reported by Akimasa Sasaki in 2012 showed that the growth of both the mutant shoots and roots was less than that of wild-type rice without any heavy metal ions treatments^[2]. And severe chlorotic symptoms could be found in the leaves of the OsNramp5 knock-out line.
When treated with heavy metal ions, no significant difference was observed in the concentration of Zn and Cu for the roots and shoots between the mutants and wild-type line. While both the concentration of Mn and Cd in the mutant roots and shoots was remarkably lower than in the wild-type line (Figure 1)^[2].

Figure 2. Expression of OsNRAMP5(from reference^[1]).

The expression analysis by Akimasa Sasaki et al. showed that OsNRAMP5 was mainly expressed in the roots. And the expression of OsNramp5 was higher in the basal root zones (1 to 2 cm from the root tip) than in the root tips (0 to 1 cm)^[2].
The expression analysis by Yasuhiro Ishimaru et al. through GUS staining, further showed that OsNRAMP5 expression was mainly expressed in roots epidermis, exodermis, and outer layers of the cortex as well as in tissues around the xylem(Figure 2)^[1].
They also found that the expression level of OsNRAMP5 decreased in root and and shoots when exposed to Cd while the expression of OsNRAMP1 increased in both tissues. No significant change was found in the expression level of other OsNRAMP family genes.
The Subcellular Localization analysis by Akimasa Sasaki et al. and Yasuhiro Ishimaru et al. both indicated that OsNRAMP5 is localized to the plasma membrane.

The Phylogenetic Analysis made by Akimasa Sasaki et al. showed that OsNramp5 exhibited 74% identity with OsNramp1 , belonging to a distinct clade from OsNramp1 and other Nramp monocot members^[2].
The closest homolog of OsNramp5 in Arabidopsis is AtNramp1, with a identity of 38%^[2].

Institute of Plant Science and Resources, Okayama University, Kurashiki 710-0046, Japan
Department of Global Agricultural Sciences; Graduate School of Agricultural and Life Sciences; The University of Tokyo;Tokyo, Japan;
Department of Chemistry, Tohoku University, 6-3 Aramakiaza-aoba, Aoba-ku, Sendai,Miyagi, 980-8579, Japan;
Grogenomics Research Center, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602 Japan,
Department of Environmental Chemistry, Heavy Metal Group, Soil Biochemistry Unit, National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki 305–8604, Japan,
Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi-shi, Ishikawa 921-8836, Japan.

↑ ^1.0 ^1.1 ^1.2 ^1.3 Ishimaru Y, Takahashi R, Bashir K, et al. Characterizing the role of rice NRAMP5 in manganese, iron and cadmium transport[J]. Scientific reports, 2012, 2.
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 ^2.7 Sasaki A, Yamaji N, Yokosho K, et al. Nramp5 is a major transporter responsible for manganese and cadmium uptake in rice[J]. The Plant Cell Online, 2012, 24(5): 2155-2167.
↑ ^3.0 ^3.1 Ishimaru Y, Bashir K, Nakanishi H, et al. OsNRAMP5, a major player for constitutive iron and manganese uptake in rice[J]. Plant signaling & behavior, 2012, 7(7): 763-766.
↑ Thomine S, Wang R, Ward J M, et al. Cadmium and iron transport by members of a plant metal transporter family in Arabidopsis with homology to Nramp genes[J]. Proceedings of the National Academy of Sciences, 2000, 97(9): 4991-4996.