Abstract
Leguminous plants establish nitrogen-fixing symbiosis with rhizobia. However, there are many unknown points in the recognition between host plants and symbiotic bacteria.
We examined the expression of symbiotic and nonsymbiotic hemoglobin genes of Lotus japonicus after inoculation of rhizobia.L. japonicus(14 days after germination) were inoculated with symbiotic (Mesorhizobium loti) or nonsymbiotic (e.g. Sinorhizobium meliloti) rhizobia, respectively. RNAs were extracted from L. japonicusat various period after rhizobial inoculation. Relative amount of transcripts derived from each hemoglobin gene was measured by quantitative RT-PCR.
When symbiotic rhizobia were inoculated, the expression of nonsym-Hb did not change in shoot but was enhanced about 2.5 times in root within 2 to 4 hours. While, in case of nonsymbiotic rhizobia, the expression levels nonsym-Hb did not change both in shoot and root. No change was detected in the expression of sym-Hb by inoculation of any rhizobia.
