cDNA macroarray analysis of gene expression in ineffective nodules induced on the Lotus japonicus sen1 mutant.
The Lotus japonicus sen1 mutant forms ineffective nodules in which development is arrested at the stage of bacterial differentiation into nitrogen-fixing bacteroids. Here, we used cDNA macroarray systems to compare gene expression in ineffective nodules induced on the sen1 mutant with gene expression in wild-type nodules, in order to identify the host plant genes that are involved in nitrogen fixation. Macroarray analysis coupled with Northern blot analysis revealed that the expression of 18 genes was significantly enhanced in ineffective sen1 nodules, whereas the expression of 30 genes was repressed. Many of the enhanced genes encoded hydrolase enzymes, such as cysteine proteinase and asparaginase, that might function in the early senescence of sen1 nodules. By contrast, the repressed genes encoded nodulins, enzymes that are involved in carbon and nitrogen metabolism, membrane transporters, enzymes involved in phytohormone metabolism and secondary metabolism, and regulatory proteins. These proteins might have a role in the establishment of nitrogen fixation. In addition, we discovered two novel genes that encoded glutamate-rich proteins and were localized in the vascular bundles of the nodules. The expression of these genes was repressed in the ineffective nodules, which had lower levels of nitrogenase activity.
Suganuma
Norio
N
Department of Life Science, Aichi University of Education, Kariya, Aichi 448-8542, Japan. nsuganum@auecc.aichi-edu.ac.jp
Yamamoto
Atsuko
A
Itou
Ai
A
Hakoyama
Tsuneo
T
Banba
Mari
M
Hata
Shingo
S
Kawaguchi
Masayoshi
M
Kouchi
Hiroshi
H
D000595:Amino Acid Sequence; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017403:In Situ Hybridization; D000070116:Lotus / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000096:biosynthesis*; D017386:Sequence Homology, Amino Acid
D010940:Plant Proteins