Reference "OsYSL2 is a rice metal-nicotianamine transporter that is regulated by iron and expressed in the phloem"

Reference ID

25478

Title

OsYSL2 is a rice metal-nicotianamine transporter that is regulated by iron and expressed in the phloem

Source

The Plant journal : for cell and molecular biology, 2004, vol. 39, pp. 415-424

Authors (7)

Koike-S	Inoue-H
Mizuno-D	Takahashi-M
Nakanishi-H	Mori-S
Nishizawa-N-K

Abstract

We identified 18 putative yellow stripe 1 (YS1)-like genes (OsYSLs) in the rice
genome that exhibited 36-76% sequence similarity to maize iron(III)-
phytosiderophore transporter YS1. Of particular interest was OsYSL2, the
transcripts of which were not detected in the roots of either iron-sufficient or
iron-deficient plants, but dramatic expression was induced in the leaves by iron
deficiency. Based on the nucleotide sequence, OsYSL2 was predicted to encode a
polypeptide of 674 amino acids containing 14 putative transmembrane domains.
OsYSL2:green fluorescent protein (GFP) was localized in the plasma membrane of
onion epidermal cells. Promoter:beta-glucuronidase (GUS) analysis revealed that
OsYSL2 was expressed in companion cells in iron-sufficient roots. GUS activity
was increased in companion cells, but no GUS staining was observed in epidermal
or cortex cells, even in iron-deficient roots. In the leaves and leaf sheaths of
iron-sufficient rice, GUS staining was observed in phloem cells of the vascular
bundles. In iron-deficient leaves, the OsYSL2 promoter was active in all tissues
with particularly strong GUS activity evident in companion cells. The phloem-
specific expression of the OsYSL2 promoter suggests that OsYSL2 is involved in
the phloem transport of iron. Strong OsYSL2 promoter activity was also detected
in developing seeds. Electrophysiological measurements using Xenopus laevis
oocytes showed that OsYSL2 transported iron(II)-nicotianamine (NA) and manganese(II)-
NA, but did not transport iron(III)-phyosiderophore. These results suggest that
OsYSL2 is 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.