A Lotus basic leucine zipper protein with a RING-finger motif negatively regulates the developmental program of nodulation.
The developmental program of nodulation is regulated systemically in leguminous host species. A mutant astray (Ljsym77) in Lotus japonicus has lost some sort of its ability to regulate this symtem, and shows enhanced and early nodulation. In the absence of rhizobia, this mutant exhibits characteristics associated with defects in light and gravity responses. These nonsymbiotic phenotypes of astray are very similar to those observed in photomorphogenic Arabidopsis mutant hy5. Based on this evidence, we predicted that astray might contain a mutation in the HY5 homologue of L. japonicus. The homologue, named LjBzf, encodes a basic leucine zipper protein in the C-terminal half that shows the highest level of identity with HY5 of all Arabidopsis proteins. It also encodes legume-characteristic combination of motifs, including a RING-finger motif and an acidic region in the N-terminal half. The astray phenotypes were cosegregated with LjBzf, and the failure to splice the intron was detected. Nonsymbiotic and symbiotic phenotypes of astray were complemented by introduction of CaMV35SLjBzf. It is noteworthy that although Arabidopsis hy5 showed an enhancement of lateral root initiation, Lotus astray showed an enhancement of nodule initiation but not of lateral root initiation. Legume-characteristic combination of motifs of ASTRAY may play specific roles in the regulation of nodule development.
Nishimura
Rieko
R
Department of Life Science, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Meguro-ku, Japan.
Ohmori
Masayuki
M
Fujita
Hironori
H
Kawaguchi
Masayoshi
M
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins; D001483:Base Sequence; D050976:Basic-Leucine Zipper Transcription Factors; D017931:DNA Primers; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005822:Genetic Vectors; D005966:Glucuronidase / Q000235:genetics; D018546:Hypocotyl / Q000502:physiology; D016350:Leucine Zippers / Q000502:physiology*; D000070116:Lotus / Q000254:growth & development / Q000502:physiology*; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000502:physiology; D030821:Plants, Genetically Modified; D011110:Polymorphism, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013559:Symbiosis
D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D017931:DNA Primers; C109254:HY5 protein, Arabidopsis; D009687:Nuclear Proteins; D010940:Plant Proteins; D005966:Glucuronidase