A node-based switch for preferential distribution of manganese in rice

Abstract

Mineral nutrients, such as manganese, are required for the development of plants and their reproductive organs, but these can be toxic if accumulated at high concentrations. Therefore, plants must have a system for preferentially delivering an adequate amount of minerals to these organs for active growth and development, while preventing mineral overaccumulation in the face of changing environments. Here we show that a member of the Nramp transporter family, OsNramp3, functions as a switch in response to environmental Mn changes. OsNramp3 is constitutively expressed in the node, a junction of vasculatures connecting leaves, stems and panicles. At low Mn concentration, OsNramp3 preferentially transports Mn to young leaves and panicles. However, at high Mn concentration, the OsNramp3 protein is rapidly degraded within a few hours, resulting in the distribution of Mn to old tissues. Our results reveal the OsNramp3-mediated strategy of rice for adapting to a wide change of Mn in the environment.

Orchestration of three transporters and distinct vascular structures in node for intervascular transfer of silicon in rice

“…Recently, identification of mineral nutrient transporters in node and physiological studies shed a new light on the importance of node for preferential distribution of mineral nutrients to developing and reproductive organs (2,14,(18)(19)(20)(21)(22)(23). The xylem flow in EVBs and DVBs, which are connected by nodal vascular anastomosis (NVA) at the base of the node, are simply divided following the transpiration rate of each upper organ.…”

“…Although different transporters are supposed to be involved in these steps, only a few of them in some steps have been identified. For instance, Lsi6 is involved in Si unloading from EVB (14, 18); OsHMA5 and OsYSL16 are involved in Cu exclusion from xylem and loading to phloem of DVB, respectively (19,20), whereas OsHMA2 is required for Zn/Cd reloading to phloem of DVB (21); and OsNramp3 has a dual role for both xylem unloading from EVB and phloem reloading to DVB of Mn (22). In the present study, by integrating in vivo experiments with mathematical modeling, we were able to identify all factors involved in the intervascular transfer for preferential distribution of Si in node (Fig.…”

Preferential Distribution of Boron to Developing Tissues Is Mediated by the Intrinsic Protein OsNIP3

“…Moreover, Arabidopsis does not have Si channel homologous to rice Lsi1 in the genome . This regulation mechanism is similar to that for Mn in rice (Yamaji et al, 2013;Shao et al, 2017). OsNramp3 in the node required for Mn distribution, rather than OsNramp5 and OsMTP9 in the roots for Mn uptake, is regulated at the protein level in response to environmental Mn change (Shao et al, 2017).…”

“…At times indicated, the roots, shoot basal region, and shoots were sampled. The expression of OsNIP3;1 was also investigated in different organs at different growth stages in rice grown in a paddy field using the same samples described previously (Yamaji et al, 2013).…”

“…Several transporters involved in the intervascular transfer from enlarged vascular bundle to diffuse vascular bundle for preferential distribution have been identified, but most transporters localized in the nodes have not been functionally characterized. Our genomewide transcriptional analysis with rice node found that a member of nodulin 26-like intrinsic protein (NIP), OsNIP3;1, was highly expressed in the node (Yamaji et al, 2013). OsNIP3;1 is the closest homolog of AtNIP5;1 .…”