Characterizing the role of rice NRAMP5 in Manganese, Iron and Cadmium Transport

Abstract

Metals like manganese (Mn) and iron (Fe) are essential for metabolism, while cadmium (Cd) is toxic for virtually all living organisms. Understanding the transport of these metals is important for breeding better crops. We have identified that OsNRAMP5 contributes to Mn, Fe and Cd transport in rice. OsNRAMP5 expression was restricted to roots epidermis, exodermis, and outer layers of the cortex as well as in tissues around the xylem. OsNRAMP5 localized to the plasma membrane, and complemented the growth of yeast strains defective in Mn, Fe, and Cd transport. OsNRAMP5 RNAi (OsNRAMP5i) plants accumulated less Mn in the roots, and less Mn and Fe in shoots, and xylem sap. The suppression of OsNRAMP5 promoted Cd translocation to shoots, highlighting the importance of this gene for Cd phytoremediation. These data reveal that OsNRAMP5 contributes to Mn, Cd, and Fe transport in rice and is important for plant growth and development.

Nramp5 Is a Major Transporter Responsible for Manganese and Cadmium Uptake in Rice

“…Furthermore, at both exodermis and endodermis cells, Nramp5 showed polar localization at the distal side (Figures 2A, 2C, and 2D). This result is different from that of a recent article, which reported that Os Nramp5 promoterb-glucuronidase activity was detected in the root epidermis, exodermis, outer layers of the cortex, and around the xylem (Ishimaru et al, 2012).…”

“…Recently, Ishimaru et al (2012) reported that knockdown of Os Nramp5 caused increased Cd accumulation in the shoots. However, in this study, either knockdown or knockout of Os Nramp5 resulted in a significant decrease of Cd in shoots grown in both solution and soil culture (Figures 3 to 5).…”

Influence of Soil Chemistry and Plant Physiology in the Phytoremediation of Cu, Mn, and Zn

“…The plasma membrane-localized NRAMP1 and NRAMP5 were shown to be high-affinity Mn transporters in Arabidopsis and rice, respectively. Both AtNRAMP1 and Os-NRAMP5 have broad selectivity, and their expression is restricted to the root (Cailliatte et al, 2010;Ishimaru et al, 2012). Furthermore, Mn uptake can also be performed by the ZmYS1 transporter, which was confirmed to be capable of acquiring Mn-PS complexes from the rhizosphere (Murata et al, 2008).…”

Functional relationship heavy metal P-type ATPases (OsHMA 2 and OsHMA3) of rice (Oryza sativa) using RNAi

“…Several studies showed that Oryza sativa natural resistance-associated macrophage protein 5 (OsNRAMP5) accounts for most of the Cd uptake from the soil by rice Ishimaru et al 2012;Sasaki et al 2012). The function of O. sativa heavy metal P-type ATPase 3 (OsHMA3) was revealed in the analysis of the rice cultivars 'Cho-Ko-Koku (CKK)' and ' Anjana Dhan,' whose shoots accumulate high levels of Cd.…”

“…However, more information about the function of transporters may be gained when combination of genes are investigated simultaneously through genetic engineering. For example, functional redundancy or an additive effect can be revealed by such studies (Hussain et al 2004;Ishimaru et al 2012). Herein, we used OsHMA3 RNA interference (RNAi) plants to investigate the relationship between OsHMA3 and OsHMA2 in plant by analyzing the F 2 progeny of OsHMA3 RNAi plants and OsHMA2 mutants that were both in the 'Nipponbare' genetic background.…”