TY - JOUR
T1 - The integral membrane protein SEN1 is required for symbiotic nitrogen fixation in lotus japonicus nodules
AU - Hakoyama, Tsuneo
AU - Niimi, Kaori
AU - Yamamoto, Takeshi
AU - Isobe, Sawa
AU - Sato, Shusei
AU - Nakamura, Yasukazu
AU - Tabata, Satoshi
AU - Kumagai, Hirotaka
AU - Umehara, Yosuke
AU - Brossuleit, Katja
AU - Petersen, Thomas R.
AU - Sandal, Niels
AU - Stougaard, Jens
AU - Udvardi, Michael K.
AU - Tamaoki, Masanori
AU - Kawaguchi, Masayoshi
AU - Kouchi, Hiroshi
AU - Suganuma, Norio
N1 - Funding Information:
This work was supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology [special coordination funds for promoting science and technology]; the Danish National Research Foundation.
PY - 2012/1
Y1 - 2012/1
N2 - Legume plants establish a symbiotic association with bacteria called rhizobia, resulting in the formation of nitrogen-fixing root nodules. A Lotus japonicus symbiotic mutant, sen1, forms nodules that are infected by rhizobia but that do not fix nitrogen. Here, we report molecular identification of the causal gene, SEN1, by map-based cloning. The SEN1 gene encodes an integral membrane protein homologous to Glycine max nodulin-21, and also to CCC1, a vacuolar iron/manganese transporter of Saccharomyces cerevisiae, and VIT1, a vacuolar iron transporter of Arabidopsis thaliana. Expression of the SEN1 gene was detected exclusively in nodule-infected cells and increased during nodule development. Nif gene expression as well as the presence of nitrogenase proteins was detected in rhizobia from sen1 nodules, although the levels of expression were low compared with those from wild-type nodules. Microscopic observations revealed that symbiosome and/or bacteroid differentiation are impaired in the sen1 nodules even at a very early stage of nodule development. Phylogenetic analysis indicated that SEN1 belongs to a protein clade specific to legumes. These results indicate that SEN1 is essential for nitrogen fixation activity and symbiosome/bacteroid differentiation in legume nodules.
AB - Legume plants establish a symbiotic association with bacteria called rhizobia, resulting in the formation of nitrogen-fixing root nodules. A Lotus japonicus symbiotic mutant, sen1, forms nodules that are infected by rhizobia but that do not fix nitrogen. Here, we report molecular identification of the causal gene, SEN1, by map-based cloning. The SEN1 gene encodes an integral membrane protein homologous to Glycine max nodulin-21, and also to CCC1, a vacuolar iron/manganese transporter of Saccharomyces cerevisiae, and VIT1, a vacuolar iron transporter of Arabidopsis thaliana. Expression of the SEN1 gene was detected exclusively in nodule-infected cells and increased during nodule development. Nif gene expression as well as the presence of nitrogenase proteins was detected in rhizobia from sen1 nodules, although the levels of expression were low compared with those from wild-type nodules. Microscopic observations revealed that symbiosome and/or bacteroid differentiation are impaired in the sen1 nodules even at a very early stage of nodule development. Phylogenetic analysis indicated that SEN1 belongs to a protein clade specific to legumes. These results indicate that SEN1 is essential for nitrogen fixation activity and symbiosome/bacteroid differentiation in legume nodules.
KW - Bacteroid differentiation
KW - Legume-Rhizobium symbiosis
KW - Lotus japonicus
KW - Nitrogen fixation
KW - Nodule
KW - Symbiosome
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U2 - 10.1093/pcp/pcr167
DO - 10.1093/pcp/pcr167
M3 - Article
C2 - 22123791
AN - SCOPUS:84862918333
VL - 53
SP - 225
EP - 236
JO - Plant and Cell Physiology
JF - Plant and Cell Physiology
SN - 0032-0781
IS - 1
ER -