Naoko K. Nishizawa

Only graminaceous monocots possess the Strategy II iron (Fe)-uptake system in which Fe is absorbed by roots as an Fe3+-phytosiderophore. In spite of being a Strategy II plant, however, rice (Oryza sativa) contains the previously identified Fe2+ transporter OsIRT1. In this study, we isolated the OsIRT2 gene from rice, which is highly homologous to OsIRT1. Real-time PCR analysis revealed that OsIRT1 and OsIRT2 are expressed predominantly in roots, and these transporters are induced by low-Fe conditions. When expressed in yeast (Saccharomyces cerevisiae) cells, OsIRT2 cDNA reversed the growth defects of a yeast Fe-uptake mutant. This was similar to the effect of OsIRT1 cDNA. OsIRT1- and OsIRT2-green fluorescent protein fusion proteins localized to the plasma membrane when transiently expressed in onion (Allium cepa L.) epidermal cells. OsIRT1 promoter-GUS analysis revealed that OsIRT1 is expressed in the epidermis and exodermis of the elongating zone and in the inner layer of the cortex of the mature zone of Fe-deficient roots. OsIRT1 expression was also detected in the ccompanion cells. Analysis using the positron-emitting tracer imaging system showed that rice plants are able to take up both an Fe3+-phytosiderophore and Fe2+. This result indicates that, in addition to absorbing an Fe3+-phytosiderophore, rice possesses a novel Fe-uptake system that directly absorbs the Fe2+, a strategy that is advantageous for growth in submerged conditions.

Plants respond to biotic and abiotic stresses by inducing overlapping sets of mitogen-activated protein kinases (MAPKs) and response genes. To define the mechanisms of how different signals can activate a common signaling pathway, upstream activators of SIMK, a salt stress- and pathogen-induced alfalfa MAPK, were identified. Here, we compare the properties of SIMKK, a MAPK kinase (MAPKK) that mediates the activation of SIMK by salt stress, with those of PRKK, a distantly related novel MAPKK. Although both SIMKK and PRKK show strongest interaction with SIMK, SIMKK can activate SIMK without stimulation by upstream factors. In contrast, PRKK requires activation by an upstream activated MAPKK kinase. SIMKK mediates pathogen elicitor signaling and salt stress, but PRKK transmits only elicitor-induced MAPK activation. Of four tested MAPKs, PRKK activates three of them (SIMK, MMK3, and SAMK) upon elicitor treatment of cells. However, PRKK is unable to activate any MAPK upon salt stress. In contrast, SIMKK activates SIMK and MMK3 in response to elicitor, but it activates only SIMK upon salt stress. These data show that (1) MAPKKs function as convergence points for stress signals, (2) MAPKKs activate multiple MAPKs, and (3) signaling specificity is obtained not only through the inherent affinities of MAPKK-MAPK combinations but also through stress signal-dependent intracellular mechanisms.

Zinc (Zn) is an essential micronutrient for plants and humans. Cadmium (Cd) is a Zn analog and one of the most toxic heavy metals to humans. Here we investigated the role of the Zn/Cd transporter OsHMA2. OsHMA2:GFP fusion protein localized to the plasma membrane in onion epidermal cells. The yeast expressing OsHMA2 was able to reverse the growth defect in the presence of excess Zn. The expression of OsHMA2 in rice was observed mainly in the roots where OsHMA2 transcripts were abundant in vascular bundles. Furthermore, Zn and Cd concentrations of OsHMA2-suppressed rice decreased in the leaves, while the Zn concentration increased in the roots compared with the wild type (WT). These results suggest that OsHMA2 plays a role in Zn and Cd loading to the xylem and participates in root-to-shoot translocation of these metals in rice. Furthermore, the Cd concentration in the grains of OsHMA2-overexpressing rice as well as in OsSUT1-promoter OsHMA2 rice decreased to about half that of the WT, although the other metal concentrations were the same as in the WT. A phenotype that reduces only the Cd concentration in rice grains will be very useful for transgenic approaches to food safety.

Cadmium (Cd) is a heavy metal toxic to humans and the accumulation of Cd in the rice grain is a major agricultural problem, particularly in Asia. The role of the iron transporter OsNRAMP1 in Cd uptake and transport in rice was investigated here. An OsNRAMP1:GFP fusion protein was localized to the plasma membrane in onion epidermal cells. The growth of yeast expressing OsNRAMP1 was impaired in the presence of Cd compared with yeast transformed with an empty vector. Moreover, the Cd content of OsNRAMP1-expressing yeast exceeded that of the vector control. The expression of OsNRAMP1 in the roots was higher in a high Cd-accumulating cultivar (Habataki) than a low Cd-accumulating cultivar (Sasanishiki) regardless of the presence of Cd, and the amino acid sequence of OsNRAMP1 showed 100% identity between Sasanishiki and Habataki. Over-expression of OsNRAMP1 in rice increased Cd accumulation in the leaves. These results suggest that OsNRAMP1 participates in cellular Cd uptake and Cd transport within plants, and the higher expression of OsNRAMP1 in the roots could lead to an increase in Cd accumulation in the shoots. Our results indicated that OsNRAMP1 is an important protein in high-level Cd accumulation in rice.

Graminaceous plants take up iron through YS1 (yellow stripe 1) and YS1-like (YSL) transporters using iron-chelating compounds known as mugineic acid family phytosiderophores. We examined the expression of 18 rice (Oryza sativa L.) YSL genes (OsYSL1-18) in the epidermis/exodermis, cortex, and stele of rice roots. Expression of OsYSL15 in root epidermis and stele was induced by iron deficiency and showed daily fluctuation. OsYSL15 restored a yeast mutant defective in iron uptake when supplied with iron(III)-deoxymugineic acid and transported iron(III)-deoxymugineic acid in Xenopus laevis oocytes. An OsYSL15-green fluorescent protein fusion was localized to the plasma membrane when transiently expressed in onion epidermal cells. OsYSL15 promoter-β-glucuronidase analysis revealed that OsYSL15 expression in roots was dominant in the epidermis/exodermis and phloem cells under conditions of iron deficiency and was detected only in phloem under iron sufficiency. These results strongly suggest that OsYSL15 is the dominant iron(III)-deoxymugineic acid transporter responsible for iron uptake from the rhizosphere and is also responsible for phloem transport of iron. OsYSL15 was also expressed in flowers, developing seeds, and in the embryonic scutellar epithelial cells during seed germination. OsYSL15 knockdown seedlings showed severe arrest in germination and early growth and were rescued by high iron supply. These results demonstrate that rice OsYSL15 plays a crucial role in iron homeostasis during the early stages of growth. Graminaceous plants take up iron through YS1 (yellow stripe 1) and YS1-like (YSL) transporters using iron-chelating compounds known as mugineic acid family phytosiderophores. We examined the expression of 18 rice (Oryza sativa L.) YSL genes (OsYSL1-18) in the epidermis/exodermis, cortex, and stele of rice roots. Expression of OsYSL15 in root epidermis and stele was induced by iron deficiency and showed daily fluctuation. OsYSL15 restored a yeast mutant defective in iron uptake when supplied with iron(III)-deoxymugineic acid and transported iron(III)-deoxymugineic acid in Xenopus laevis oocytes. An OsYSL15-green fluorescent protein fusion was localized to the plasma membrane when transiently expressed in onion epidermal cells. OsYSL15 promoter-β-glucuronidase analysis revealed that OsYSL15 expression in roots was dominant in the epidermis/exodermis and phloem cells under conditions of iron deficiency and was detected only in phloem under iron sufficiency. These results strongly suggest that OsYSL15 is the dominant iron(III)-deoxymugineic acid transporter responsible for iron uptake from the rhizosphere and is also responsible for phloem transport of iron. OsYSL15 was also expressed in flowers, developing seeds, and in the embryonic scutellar epithelial cells during seed germination. OsYSL15 knockdown seedlings showed severe arrest in germination and early growth and were rescued by high iron supply. These results demonstrate that rice OsYSL15 plays a crucial role in iron homeostasis during the early stages of growth. Iron is essential for virtually all living organisms. Iron deficiency is the most widespread human nutritional problem in the world. There are two billion anemic people worldwide, and ∼50% of all anemia cases can be attributed to iron deficiency (1Mason J.B. Lotfi M. Dalmiya N. Sethuraman K. Deitchler M. Geibel S. Gillenwater K. Gilman A. Mason K. Mock N. The Micronutrient Report: Current Progress and Trends in the Control of Vitamin A, Iodine, and Iron Deficiencies. The Micronutrient Initiative/International Development Research Center, Ottawa, Canada2001: 1-40Google Scholar). In plants, iron plays a key role in electron transfer in both photosynthetic and respiratory reactions in chloroplasts and mitochondria. Although abundant in mineral soils, iron is sparingly soluble under aerobic conditions at high soil pH. Consequently, plants grown on calcareous soils often exhibit severe chlorosis because of iron deficiency, which is a major agricultural problem resulting in reduced crop yields (2Marschner H. Mineral Nutrition of Higher Plants.2nd Ed. Academic Press, London, UK1995: 313-324Crossref Google Scholar). Higher plants have two strategies for the uptake of oxidized Fe(III) from the rhizosphere (3Römheld V. Marschner H. Plant Physiol.. 1986; 80: 175-180Google Scholar). All higher plants except graminaceous plants take up iron by using ferric-chelate reductases to reduce ferric iron to Fe(II), which is absorbed by ferrous iron transporters (strategy I (4Eide D. Broderuis M. Fett J. Guerinot M.L. Proc. Natl. Acad. Sci. U. S. A.. 1996; 93: 5624-5628Google Scholar, 5Robinson N.J. Procter C.M. Connolly E.L. Guerinot M.L. Nature.. 1999; 397: 694-697Google Scholar, 6Vert G. Grotz N. Dedaldechamp F. Gaymard F. Guerinot M.L. Briat J.F. Curie C. Plant Cell.. 2002; 14: 1223-1233Google Scholar)). Alternatively, graminaceous plants secrete iron chelators called mugineic acid family phytosiderophores (MAs) 4The abbreviations used are: MA, mugineic acid family phytosiderophore; DMA, 2′-deoxymugineic acid; GFP, green fluorescent protein; GUS, β-glucuronidase; VC, vector control; MS, Murashige and Skoog medium; RT, reverse transcription; ORF, open reading frame; MES, 4-morpholineethanesulfonic acid; NA, nicotianamine; TM, transmembrane domain; IDEF, iron deficiency-responsive element-binding factor; CBS, circadian clock-associated 1-binding site. 4The abbreviations used are: MA, mugineic acid family phytosiderophore; DMA, 2′-deoxymugineic acid; GFP, green fluorescent protein; GUS, β-glucuronidase; VC, vector control; MS, Murashige and Skoog medium; RT, reverse transcription; ORF, open reading frame; MES, 4-morpholineethanesulfonic acid; NA, nicotianamine; TM, transmembrane domain; IDEF, iron deficiency-responsive element-binding factor; CBS, circadian clock-associated 1-binding site. from their roots to solubilize iron in the rhizosphere (strategy II (3Römheld V. Marschner H. Plant Physiol.. 1986; 80: 175-180Google Scholar, 7Takagi S. Soil Sci. Plant Nutr.. 1976; 22: 423-433Google Scholar, 8Mori S. Curr. Opin. Plant Biol.. 1999; 2: 250-253Google Scholar)). These chelating MAs have six coordination sites (three –COOH, two –NH, and one -OH) that bind to iron and are thought to form octahedral Fe(III) complexes. Graminaceous plants then take up the iron as Fe(III)-MAs complexes from the rhizosphere through specific transporters (9Mihashi S. Mori S. Biol. Metals.. 1989; 2: 146-154Google Scholar, 10Curie C. Panavience Z. Loulergue C. Dellaporta S.L. Briat J.F. Walker E.L. Nature.. 2001; 409: 346-349Google Scholar). The biosynthetic pathway for MAs in graminaceous plants has been elucidated (8Mori S. Curr. Opin. Plant Biol.. 1999; 2: 250-253Google Scholar, 11Mori S. Nishizawa N. Plant Cell Physiol.. 1987; 28: 1081-1092Google Scholar, 12Shojima S. Nishizawa N.K. Fushiya S. Nozoe S. Irifune T. Mori S. Plant Physiol.. 1990; 93: 1497-1503Google Scholar, 13Ma J.F. Nomoto K. Plant Physiol.. 1993; 102: 373-378Google Scholar, 14Ma J.F. Taketa S. Chang Y.C. Iwashita T. Matsumoto H. Takeda K. Nomoto K. Planta.. 1999; 207: 590-596Google Scholar). Methionine, the precursor of MAs (11Mori S. Nishizawa N. Plant Cell Physiol.. 1987; 28: 1081-1092Google Scholar), is converted to 2′-deoxymugineic acid (DMA) via several enzymatic reactions. Whereas rice (Oryza sativa L.) and maize (Zea mays L.) secrete DMA, other species, including barley (Hordeum vulgare L.) and rye (Secale cereale L.), further hydroxylate DMA to other MAs. The production and secretion of MAs markedly increase in to iron The secretion of MAs in barley a with a S. Nomoto K. T. J. Plant Nutr.. Scholar). The of the secretion of MAs in rice has been The genes that the biosynthetic in the pathway to MAs have been and in barley and and and K. K. H. H. Nishizawa N.K. Mori S. Plant Physiol.. 1999; Scholar, A. G. Mock M. A. J. H. J. 1999; Scholar, M. H. H. T. Nishizawa N.K. Mori S. Plant Physiol.. 1999; Scholar, K. H. S. M. H. Mori S. Nishizawa N.K. J. Biol. and rice and K. H. S. M. H. Mori S. Nishizawa N.K. J. Biol. Scholar, K. S. M. S. H. Nishizawa N.K. Mori S. Plant 2001; Scholar, H. M. T. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar)). Expression of genes is strongly induced in to iron In analysis of promoter-β-glucuronidase revealed that and expression with expression in all cells of roots in the and cells K. H. S. M. H. Mori S. Nishizawa N.K. J. Biol. Scholar, H. M. T. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar, H. K. M. H. Mori S. Nishizawa N.K. Plant Scholar), DMA is thought to be of the maize YS1 (yellow stripe 1) C. Panavience Z. Loulergue C. Dellaporta S.L. Briat J.F. Walker E.L. Nature.. 2001; 409: 346-349Google to the of the specific transporters responsible for uptake of MAs complexes from the rhizosphere root cells. The maize mutant is defective in Fe(III)-MAs uptake N. Mori S. Marschner H. V. Plant Physiol.. Scholar). YS1 expression is in both roots and under conditions of iron deficiency, is strongly by deficiency C. Panavience Z. Loulergue C. Dellaporta S.L. Briat J.F. Walker E.L. Nature.. 2001; 409: 346-349Google Scholar, Z. Walker E.L. Plant Physiol.. Scholar). G. U. Mori S. T. N. J. Biol. the transport of YS1 in Xenopus by YS1 as a for including and YS1 also Fe(II), and Fe(III) complexes. a barley of YS1 has been J.F. N. D. Nomoto K. Iwashita T. Plant Scholar). In to is specific for Fe(III)-MAs a transport for MAs to plants also YS1-like (YSL) genes that transporters to in homeostasis by as plants MAs T. Walker E.L. Plant Scholar, M. A. S. Briat J.F. Curie C. Plant Scholar, G. A. J. G. U. Briat J.F. Curie C. N. Plant Cell Physiol.. Scholar, D. G. K. Briat J.F. M. S. Plant Scholar, D. Walker E.L. Plant Physiol.. Scholar). for YS1 in the rice 18 genes S. H. D. M. H. Mori S. Nishizawa N.K. Plant Scholar). are and Fe(III)-MAs S. H. D. M. H. Mori S. Nishizawa N.K. Plant Scholar). expression is strongly induced in with expression in phloem cells of the and These results suggest that as transporter responsible for the phloem transport of iron S. H. D. M. H. Mori S. Nishizawa N.K. Plant Scholar). rice with a transport for Fe(III)-MAs has been that OsYSL15 a expression strongly in uptake from the rhizosphere and phloem transport of iron. An essential role of OsYSL15 for transport of iron during early growth is also by the results Plant and rice were on Murashige and Skoog and to (11Mori S. Nishizawa N. Plant Cell Physiol.. 1987; 28: 1081-1092Google Scholar, H. K. M. H. Mori S. Nishizawa N.K. Plant in a with under The of the was daily to with deficiency plants were to and grown for expression analysis was as T. S. M. H. Mori S. Nishizawa N.K. Soil Sci. Plant Nutr.. Scholar). were grown under conditions for and were at the were on The were at and were on at and were from rice and Expression was used to expression M. F. Plant Cell.. Scholar). and roots were by a of acid the under on The the in the were then on a at for was with a of The were then to and the were with under for on by on a at for with a the were on a at The were then in in a and at The were in a and on with a of at The was to a and at The were with a were and from the of the epidermis/exodermis, cortex, and stele were and in the of the in at was from the using to the The of was using a with and to the was used to using and reverse of the resulting was used in a with the specific in a rice were The were by in of were used in and cells were grown in yeast and supplied with the was to for complexes were as G. U. Mori S. T. N. J. Biol. was by of a and and DMA for at The was through to iron. The yeast expression and G. A. J. G. U. Briat J.F. Curie C. N. Plant Cell Physiol.. were the of of sites and were in the using the and expression of OsYSL15 in the OsYSL15 was using and sites and the sites of the vector to form cells were using the Biol.. Scholar). of yeast cells were in iron for The cells were in of The of the was to and of were to for of OsYSL15 in Xenopus laevis of OsYSL15 transport using laevis was to S. H. D. M. H. Mori S. Nishizawa N.K. Plant of OsYSL15 was by using a from rice roots and and with OsYSL15 were used to were also in six as was by and analysis was as H. K. M. H. Mori S. Nishizawa N.K. Plant Scholar). specific for OsYSL15 was by using a from rice roots and the as used for the analysis of analysis of roots and seedlings was as H. M. T. M. H. Mori S. Nishizawa N.K. Plant Biol.. using the specific in of open reading of OsYSL15 was using two and The was vector was M. T. M. H. Mori S. Nishizawa N.K. J. as the reactions the vector and the vector expression the epidermal cells were using the and the transiently expressed was using a to D. K. T. H. Mori S. Nishizawa N.K. Plant Physiol.. OsYSL15 of the OsYSL15 to from the was by using as a The used were the and the reverse The and was using and and of the ORF, which GUS, in the vector S. T. T. Plant Scholar). An the was used to rice sativa as K. S. M. S. H. Nishizawa N.K. Mori S. Plant 2001; Scholar). were and as and to expression analysis as H. K. M. H. Mori S. Nishizawa N.K. Plant Scholar). during seed germination was as T. H. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar). and of OsYSL15 OsYSL15 a of the OsYSL15 was by with the and and the was a vector The was H. T. M. Mori S. Nishizawa N.K. Plant by and used for rice OsYSL15 knockdown were on with of and S. Plant Nutrition for and Scholar)). analysis of were on with of for and then to for Expression of in used to the rice sativa resulting in 18 genes S. H. D. M. H. Mori S. Nishizawa N.K. Plant Scholar). of the 18 in the epidermis/exodermis, cortex, and stele of and roots were using M. F. Plant Cell.. Expression of OsYSL15 and was induced in the epidermis/exodermis and stele of roots Expression of and was detected in all of both and roots. Expression of was by iron deficiency, and expression of was detected in the and stele under both and Expression of was detected in both and expression of and was detected in of the We to on the OsYSL15 because expression was strongly in the root epidermis under conditions of iron deficiency, that protein is to a role in iron uptake from the and of OsYSL15 has a open reading The is on one of and has as YS1 and C. Panavience Z. Loulergue C. Dellaporta S.L. Briat J.F. Walker E.L. Nature.. 2001; 409: 346-349Google Scholar, S. H. D. M. H. Mori S. Nishizawa N.K. Plant Scholar). the of of OsYSL15 is with the of OsYSL15 and are on the and by a on the OsYSL15 is to a protein of OsYSL15 was most to the maize YS1 transporter C. Panavience Z. Loulergue C. Dellaporta S.L. Briat J.F. Walker E.L. Nature.. 2001; 409: 346-349Google with the other acid analysis of OsYSL15 using transmembrane with the in the the high of OsYSL15 and two to The the and showed In of the acid of the protein C. Panavience Z. Loulergue C. Dellaporta S.L. Briat J.F. Walker E.L. Nature.. 2001; 409: 346-349Google Scholar), the in OsYSL15 The of and showed OsYSL15 and YS1 is to the the which the responsible for and of transporters K. K. Iwashita T. Scholar). acid of revealed YS1 and OsYSL15 with a in at the OsYSL15 yeast using a mutant defective in high and iron uptake J. Biol. was used to the transport of OsYSL15 rescued the growth of the mutant on complexes YS1 also rescued the yeast from the growth the vector with C. Panavience Z. Loulergue C. Dellaporta S.L. Briat J.F. Walker E.L. Nature.. 2001; 409: 346-349Google Scholar, G. U. Mori S. T. N. J. Biol. Scholar). of OsYSL15 YS1 on yeast grown on and with laevis were used to further transported by OsYSL15 was expressed in the and the at were in to several compounds OsYSL15 transported transport complexes. results were under of OsYSL15 Expression by Micronutrient and of OsYSL15 was for known the to iron deficiency in rice plants T. H. T. Mori S. Nishizawa N.K. Plant Scholar, T. H. M. Mori S. Nishizawa N.K. Proc. Natl. Acad. Sci. U. S. A.. Scholar, T. H. M. S. Mori S. Nishizawa N.K. J. Biol. Scholar, H. H. T. M. M. Mori S. Nishizawa N.K. J. Scholar), OsYSL15 T. H. M. Mori S. Nishizawa N.K. Proc. Natl. Acad. Sci. U. S. A.. at to from the and sites T. H. M. S. Mori S. Nishizawa N.K. J. Biol. a circadian clock-associated 1-binding which circadian expression Plant Physiol.. 2002; Scholar), was at to from the site. OsYSL15 expression is by in and analysis with S. H. D. M. H. Mori S. Nishizawa N.K. Plant and analysis OsYSL15 expression was strongly in roots in In deficiency OsYSL15 in roots In expression of OsYSL15 showed a daily The the of and to the at the of and of OsYSL15 of OsYSL15 was using green fluorescent protein OsYSL15 protein transiently expressed in onion L.) epidermal cells. the fusion protein in the plasma membrane Control using cells showed in the and the OsYSL15 is a transporter for uptake of through the plasma The OsYSL15 to and rice was used to of OsYSL15 expression in rice plants the OsYSL15 were grown under All showed of OsYSL15 OsYSL15 was detected in the of roots higher was only in phloem cells of rice roots showed that the was in specific of the phloem cells of the cells of roots were also In the OsYSL15 was in all including cortex, and the was in phloem cells was detected in the cells I in the roots in roots and showed in the root cells In the OsYSL15 was in cells and in of the of Iron deficiency expression The OsYSL15 was also in and developing was dominant in the of and to expression was in the and was in the of developing and Expression was in the and expression was in the and OsYSL15 in further the of of rice OsYSL15 knockdown plants with expression These during with vector and only of OsYSL15 expression seed germination and early severe growth when grown on revealed that expression of OsYSL15 was to and with seedlings Expression of of including and was in seedlings of plants grown on were to and with plants and plants grown on severe growth with to and of of plants and These growth were restored when plants were grown on a with of plants and of when grown on and of OsYSL15 expression was with growth to The showed the growth on and the most showed the of growth on a and plants on and further the OsYSL15 expression and seed OsYSL15 expression during seed germination using OsYSL15 The OsYSL15 was during seed germination The was in the from to with expression Expression was also in the of and in and seedlings and of OsYSL15 during seed germination was also in analysis There was in iron in the of plants and plants OsYSL15 in the of Iron from the II iron uptake in graminaceous plants has as 1) of MAs in MAs secretion to the and uptake of Fe(III) through the membrane of root cells (3Römheld V. Marschner H. Plant Physiol.. 1986; 80: 175-180Google Scholar). the rice of YSL for Fe(III)-MAs the expression of the 18 genes in root to the that the OsYSL15 which is strongly in the root epidermis under conditions of iron deficiency is responsible for iron uptake from the of OsYSL15 transport to transport strongly the that rice up from the rhizosphere using OsYSL15 transporter under OsYSL15 analysis revealed expression in the epidermal and cells of roots and of complexes In DMA is and thought to be the rhizosphere to solubilize oxidized and at from the root are the dominant for iron uptake in barley roots (9Mihashi S. Mori S. Biol. Metals.. 1989; 2: 146-154Google Scholar). expression of OsYSL15 as as of and K. H. S. M. H. Mori S. Nishizawa N.K. J. Biol. Scholar, H. M. T. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar, H. K. M. H. Mori S. Nishizawa N.K. Plant with the of DMA production and from the The secretion of MAs in barley a S. Nomoto K. T. J. Plant Nutr.. Scholar). in secretion and Although secretion of MAs from rice roots is because of the of MAs with rice genes in DMA including and exhibit in expression T. S. M. H. Mori S. Nishizawa N.K. Soil Sci. Plant Nutr.. Scholar). of genes increase to and of genes T. S. M. H. Mori S. Nishizawa N.K. Soil Sci. Plant Nutr.. Scholar). the of a in the of OsYSL15 and daily in OsYSL15 expression with expression during the of These results suggest that OsYSL15 in uptake with and secretion of In rice DMA be at and in the OsYSL15 is thought to be responsible for uptake of complexes in the daily in expression is also for barley S. M. K. H. Mori S. Nishizawa N.K. Plant Scholar). and secretion of DMA is strongly induced under conditions of iron to the genes responsible for DMA OsYSL15 was by iron deficiency and that iron the iron expression of OsYSL15 as as the genes responsible for DMA including and H. T. M. Mori S. Nishizawa N.K. Plant Scholar). OsYSL15 sites H. H. T. M. M. Mori S. Nishizawa N.K. J. OsYSL15 is thought to be by of iron deficiency-responsive element-binding revealed that and which bind to and iron homeostasis in rice T. H. M. Mori S. Nishizawa N.K. Proc. Natl. Acad. Sci. U. S. A.. Scholar, T. H. M. S. Mori S. Nishizawa N.K. J. Biol. Scholar). The of and sites in the OsYSL15 that OsYSL15 expression is by in the and other with uptake through rice plants also take up as iron via the transporter M. T. K. M. T. S. S. M. H. Mori S. Nishizawa N.K. Plant Scholar). rice plants ferric-chelate higher iron uptake and iron deficiency S. T. H. T. S. S. M. H. Mori S. Nishizawa N.K. Proc. Natl. Acad. Sci. U. S. A.. Scholar), of ferrous iron uptake in F. H. F. F. J. D. J.F. Plant Physiol.. that a rice mutant defective in DMA is under aerobic conditions is to under when is These results suggest that of uptake through OsYSL15 uptake through is strongly on growth OsYSL15 knockdown plants showed only during the further of other knockdown plants, by using the role of OsYSL15 in iron uptake from the of OsYSL15 in of is in both rice and roots K. S. M. S. H. Nishizawa N.K. Mori S. Plant 2001; Scholar), as as rice phloem S. Nishizawa N. H. M. J. Plant Scholar). the genes in DMA including and are markedly expressed in phloem cells in rice roots and K. H. S. M. H. Mori S. Nishizawa N.K. J. Biol. Scholar, H. M. T. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar, H. K. M. H. Mori S. Nishizawa N.K. Plant Scholar). expression of OsYSL15 in the phloem cells in roots the that OsYSL15 in the transport of complexes from roots to via analysis revealed that is to rice at higher M. T. H. S. S. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar), role of DMA in the in to from the OsYSL15 and in transport of iron in the and in the cells and be transported to through is strongly expressed in phloem cells in and protein complexes S. H. D. M. H. Mori S. Nishizawa N.K. Plant Scholar). a of Scholar), in which complexes are to be N. S. S. Briat J.F. H. T. Plant Physiol.. 1999; Scholar). of are in rice K. S. M. S. H. Nishizawa N.K. Mori S. Plant 2001; Scholar). of Fe(III) and are for of to complexes. rice genes ferric-chelate in the plasma membrane M. T. K. M. T. S. S. M. H. Mori S. Nishizawa N.K. Plant ferric-chelate in the S. M. M. Briat J.F. 1999; reduce ferrous of complexes. is to from DMA to in the phloem cells as the is at high N. S. S. Briat J.F. H. T. Plant Physiol.. 1999; Scholar). In to phloem OsYSL15 is expressed in root cells to the genes in DMA including and are markedly expressed K. H. S. M. H. Mori S. Nishizawa N.K. J. Biol. Scholar, H. M. T. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar, H. K. M. H. Mori S. Nishizawa N.K. Plant Scholar). OsYSL15 be the transporter for transport of complexes in and are also expressed in the root stele be in of is transporters for complexes also be for in to including transporter of the and has been to be in which is for iron transport the Plant Physiol.. Scholar). rice is expressed in root cells to the and I H. M. M. H. Mori S. Nishizawa N.K. Soil Sci. Plant Nutr.. Scholar). in to as iron be responsible for transport of iron via of OsYSL15 during and knockdown plants severe arrest in seed germination early which was severe in and was rescued by high of These results that iron transport is essential for seed germination. OsYSL15 is expressed in the embryonic scutellar cells during seed germination OsYSL15 transport from through the epithelial The epithelial in the of the the and in the of from K. The Scholar). iron in the is higher that in the F. T. N. S. F. 1999; Scholar). seed OsYSL15 is expressed in and and are also expressed in high of DMA also K. H. H. S. and N. K. DMA be used to form complexes during seed germination. In OsYSL15 a role in of complexes the from the OsYSL15 was expressed in the and cells of seedlings and are expressed in the T. H. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar), to and secretion of DMA for iron from the soil during seed germination. In transporters are in early growth. defective in transport at the root are to are strongly G. Grotz N. Dedaldechamp F. Gaymard F. Guerinot M.L. Briat J.F. Curie C. Plant Cell.. 2002; 14: 1223-1233Google Scholar). mutant of the transporters and germination transporters a role in of iron during seed germination V. F. S. C. C. D. G. Curie C. A. U. H. S. Scholar). mutant defective in membrane transporter on high soil T. A. J. Guerinot M.L. Scholar). In to the of OsYSL15 complexes that DMA is the essential for rice seed germination. with F. H. F. F. J. D. J.F. Plant Physiol.. that a rice mutant defective in DMA is to germination when supplied with as the iron the ferrous transporter is expressed in the of the and the in the embryonic scutellar cells T. H. M. H. Mori S. Nishizawa N.K. Plant Biol.. Scholar). DMA to a crucial role in iron from the acid of seed and is in as of and also other mineral as and J. Nutr.. 1976; Scholar, V. and of Plant Academic The Scholar, Academic Press, Scholar). DMA strongly ferric iron N. S. S. Briat J.F. H. T. Plant Physiol.. 1999; and is thought to be in the Fe(III) from in the form of iron. in high the of iron T. Scholar, M. A. J. Nutr.. Scholar). Although iron in rice is high with other human DMA and complexes in the iron of OsYSL15 expression in with genes in DMA other transporter the genes in iron the for of for human as as production in We of for and of for the maize YS1 and of of and for the of for on yeast and of for on and rice and of for the with