Symbiotic rhizobium and nitric oxide induce gene expression of non-symbiotic hemoglobin in Lotus japonicus.
We characterized the expression profiles of LjHb1 and LjHb2, non-symbiotic hemoglobin (non-sym-Hb) genes of Lotus japonicus. Although LjHb1 and LjHb2 showed 77% homology in their cDNA sequences, LjHb2 is located in a unique position in the phylogenetic tree of plant Hbs. The 5'-upstream regions of both genes contain the motif AAAGGG at a position similar to that in promoters of other non-sym-Hb genes. Expression profiles obtained by using quantitative RT-PCR showed that LjHb1 and LjHb2 were expressed in all tissues of mature plants, and expression was enhanced in mature root nodules. LjHb1 was strongly induced under both hypoxic and cold conditions, and by the application of nitric oxide (NO) donor, whereas LjHb2 was induced only by the application of sucrose. LjHb1 was also induced transiently by the inoculation with the symbiotic rhizobium Mesorhizobium loti MAFF303099. Observations using fluorescence microscopy revealed the induction of LjHb1 expression corresponded to the generation of NO. These results suggest that non-sym-Hb and NO have important roles in stress adaptation and in the early stage of legume-rhizobium symbiosis.
Shimoda
Yoshikazu
Y
Graduate School of Science and Technology, Kagoshima University, Kagoshima, 890-0065 Japan.
Nagata
Maki
M
Suzuki
Akihiro
A
Abe
Mikiko
M
Sato
Shusei
S
Kato
Tomohiko
T
Tabata
Satoshi
S
Higashi
Shiro
S
Uchiumi
Toshiki
T
D020561:Alphaproteobacteria / Q000378:metabolism*; D001483:Base Sequence; D018744:DNA, Plant / Q000235:genetics; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D006454:Hemoglobins / Q000235:genetics*; D000070116:Lotus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic; D013559:Symbiosis
D018744:DNA, Plant; D006454:Hemoglobins; D020030:Nitric Oxide Donors; D010937:Plant Growth Regulators; D010940:Plant Proteins; D009569:Nitric Oxide