OsYSL2 was reported by researchers from Japan as a rice metal-NA transporter that is responsible for the phloem transport of iron and manganese, including the translocation of iron and manganese into the grain.
- OsYSL2 is an Fe-regulated metal-NA transporter that is involved in phloem transport and the translocation of mineral nutrients in grains. The altered expression of OsYSL2changes the localization of Fe, and that OsYSL2 is a critical Fe-nicotianamine transporter important for Fe translocation,especially in the shoots and endosperm .
- Based on the nucleotide sequence,OsYSL2 was predicted to encode a polypeptide of 674 amino acids containing 14 putative transmembrane domains. Cells expressing the OsYSL2–GFP fusion protein showed a signal in the plasma membrane, with the presence of the putative transmembrane domains shows that OsYSL2 is a transporter that is localized in the plasma membrane.
- Yasuhiro Ishimaru et al. produced OsYSL2 knock-down lines using the RNAi method. Seven independent lines were generated, and the expression of endogenous OsYSL2 in T1OsYSL2i leaves of lines 3 and 5 was suppressed, as revealed by northern blot analysis(Figure 1a). Fe concentrations in the seeds were also decreased in lines 3 and 5,consistent with the suppression of OsYSL2(Figure 1b).At the early growth stage, the growth of line 5 was impaired compared with the WT, when grown under Fe-sufficient conditions. These growth defects appeared to be more significant when grown under Fe-deficient conditions (Figure 1c–e).
- Yasuhiro Ishimaru et al. assessed whether the over expression of OsYSL2(OXOsYSL2) in rice plants could enhance Fe accumulation in the seeds. Constitutive over expression of OsYSL2 decreased the Fe concentration in the brown rice and shoots ,although the Fe concentration was higher in the roots of OXOsYSL2 plants. On the other hand, the Mn concentration was increased in the brown rice and decreased in the roots of OXOsYSL2 plants.
- OsYSL2 was of particular interest because no detectable transcripts were present in the roots of either Fe-sufficient or Fe-deficient plants, but dramatic expression was induced in the leaves of Fe-deficient plants.Research by Yasuhiro Ishimaru et al. showed that the high expression of OsYSL2 in the roots under Fe deficiency was not consistent with previous study.
- The cell-type specificity of OsYSL2 expression was investigated using promoter (1.5 kb):b-glucuronidase (GUS) analysis.GUS staining was observed in phloem cells of the vascular bundles of leaves and leaf sheaths of Fe-sufficient rice. The phloem-specific expression of the OsYSL2 promoter suggested that OsYSL2 is involved in the phloem transport of Fe . OsYSL2 is expressed during reproductive development in rice. RT-PCR analysis confirmed that OsYSL2 transcripts were increased during early seed development(figure 2).
- In fully mature seeds,strong OsYSL2 expression was observed in the epithelium, the vascular bundle of the scutellum, and the leaf primordium . Two days after sowing, the OsYSL2 expression level increased in the scutellum near the endosperm. Three days after sowing,OsYSL2 expression was observed in the bran and coleoptile.
YS1-like genes in rice Our search for YS1 homologus in the Oryza sativaL. Ssp. japonica (cv. Nipponbare) rice genomic database identified 18 putative OsYSL that exhibited 36–76% sequence similarity to YS1(figure 3) .
Labs working on this gene
- Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Kawaguchi 332-0012, Japan
- National Agricultural Research Center, 1-2-1 Inada, Joetsu, Niigata 943-0193, Japan
- Koike S, Inoue H, Mizuno D, et al. OsYSL2 is a rice metal‐nicotianamine transporter that is regulated by iron and expressed in the phloem[J]. The Plant Journal, 2004, 39(3): 415-424.PMID 15255870
- Ishimaru Y, Masuda H, Bashir K, et al. Rice metal‐nicotianamine transporter, OsYSL2, is required for the long‐distance transport of iron and manganese[J]. The Plant Journal, 2010, 62(3): 379-390.PMID 20128878
- Nozoye T, Inoue H, Takahashi M, et al. The expression of iron homeostasis-related genes during rice germination[J]. Plant molecular biology, 2007, 64(1-2): 35-47.PMID 17333504