RRC ID 54189
Author Sugiyama A, Saida Y, Yoshimizu M, Takanashi K, Sosso D, Frommer WB, Yazaki K.
Title Molecular Characterization of LjSWEET3, a Sugar Transporter in Nodules of Lotus japonicus.
Journal Plant Cell Physiol.
Abstract Symbiotic nitrogen fixation in legumes contributes greatly to the global nitrogen cycle on the earth. In nodules, resident rhizobia supply nitrogen nutrient fixed from atmospheric N2 to the host plant; in turn, the plant provides photosynthetic metabolites to bacteroids as a carbon source. In this process, various transporters are involved at different membrane systems; however, little is known at the molecular level about the flow of carbon from the host cells to the symbiotic bacteria. We have been studying transporters functioning in nodules of Lotus japonicus, and found that out of 13 SWEET genes in the L. japonicus genome LjSWEET3, a member of the SWEET transporter family, is highly expressed in nodules. The SWEET family was first identified in Arabidopsis, where members of the family are involved in phloem loading, nectar secretion, pollen nutrition and seed filling. The expression of LjSWEET3 strongly increased during nodule development and reached the highest level in mature nodules. Histochemical analysis using L. japonicus plants transformed with LjSWEET3 promoter:GUS (β-glucuronidase) showed strong expression in the vascular systems of nodules. Analysis of an LjSWEET3-green fluorescent protein (GFP) fusion expressed in Nicotiana banthamiana and Coptis japonica indicates that LjSWEET3 localizes to the plasma membrane. Together these data are consistent with a role for LjSWEET3 in sugar translocation towards nodules and also suggest the possible existence of multiple routes of carbon supply into nodules.
Volume 58(2)
Pages 298-306
Published 2017-2-1
DOI 10.1093/pcp/pcw190
PII pcw190
PMID 28007966
MeSH Gene Expression Regulation, Plant / genetics Gene Expression Regulation, Plant / physiology Lotus / genetics Lotus / metabolism* Nitrogen Fixation / genetics Nitrogen Fixation / physiology Plant Proteins / genetics Plant Proteins / metabolism Promoter Regions, Genetic / genetics Root Nodules, Plant / genetics Root Nodules, Plant / metabolism Sucrose / metabolism
IF 3.929
Resource
Lotus / Glycine Miyakojima MG-20 pUB-GWS-GFP