title: Lotus japonicus nodulation is photomorphogenetically controlled by sensing the red/far red (R/FR) ratio through jasmonic acid (JA) signaling.
abstract: Light is critical for supplying carbon to the energetically expensive, nitrogen-fixing symbiosis between legumes and rhizobia. Here, we show that phytochrome B (phyB) is part of the monitoring system to detect suboptimal light conditions, which normally suppress Lotus japonicus nodule development after Mesorhizobium loti inoculation. We found that the number of nodules produced by L. japonicus phyB mutants is significantly reduced compared with the number produced of WT Miyakojima MG20. To explore causes other than photoassimilate production, the possibility that local control by the root genotype occurred was investigated by grafting experiments. The results showed that the shoot and not the root genotype is responsible for root nodule formation. To explore systemic control mechanisms exclusive of photoassimilation, we moved WT MG20 plants from white light to conditions that differed in their ratios of low or high red/far red (R/FR) light. In low R/FR light, the number of MG20 root nodules dramatically decreased compared with plants grown in high R/FR, although photoassimilate content was higher for plants grown under low R/FR. Also, the expression of jasmonic acid (JA) -responsive genes decreased in both low R/FR light-grown WT and white light-grown phyB mutant plants, and it correlated with decreased jasmonoyl-isoleucine content in the phyB mutant. Moreover, both infection thread formation and root nodule formation were positively influenced by JA treatment of WT plants grown in low R/FR light and white light-grown phyB mutants. Together, these results indicate that root nodule formation is photomorphogenetically controlled by sensing the R/FR ratio through JA signaling.
authors.affiliation: Department of Agricultural Sciences, Faculty of Agriculture, Saga University, Honjyo-machi, Saga, Saga 840-8502, Japan. azuki@cc.saga-u.ac.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Suzuki
authors.forename: Lalith
authors.initials: L
authors.lastname: Suriyagoda
authors.forename: Tamaki
authors.initials: T
authors.lastname: Shigeyama
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Tominaga
authors.forename: Masayo
authors.initials: M
authors.lastname: Sasaki
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Hiratsuka
authors.forename: Aya
authors.initials: A
authors.lastname: Yoshinaga
authors.forename: Susumu
authors.initials: S
authors.lastname: Arima
authors.forename: Sakae
authors.initials: S
authors.lastname: Agarie
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sakai
authors.forename: Sayaka
authors.initials: S
authors.lastname: Inada
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Jikumaru
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kamiya
authors.forename: Toshiki
authors.initials: T
authors.lastname: Uchiumi
authors.forename: Mikiko
authors.initials: M
authors.lastname: Abe
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Hashiguchi
authors.forename: Ryo
authors.initials: R
authors.lastname: Akashi
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Takakazu
authors.initials: T
authors.lastname: Kaneko
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Ann M
authors.initials: AM
authors.lastname: Hirsch
mesh_terms: D001483:Base Sequence; D003517:Cyclopentanes / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D007532:Isoleucine / Q000031:analogs & derivatives / Q000378:metabolism; D008027:Light; D000070116:Lotus / Q000382:microbiology / Q000502:physiology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation / Q000235:genetics; D054883:Oxylipins / Q000378:metabolism*; D051939:Phytochrome B / Q000235:genetics / Q000378:metabolism; D055170:Plant Root Nodulation / Q000502:physiology*; D018520:Plant Shoots / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012231:Rhizobium / Q000502:physiology*; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000502:physiology*; D013559:Symbiosis
chemical_list: D003517:Cyclopentanes; D017931:DNA Primers; D054883:Oxylipins; C532883:jasmonoyl-isoleucine; D007532:Isoleucine; D051939:Phytochrome B; C011006:jasmonic acid