Hiroshi Kouchi

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We took advantage of a subtractive hybridization procedure to isolate a set of cDNA clones of nodule-specific genes (nodulin genes) from developing soybean root nodules. Single-standed 32P-labelled cDNA synthesized from nodule poly(A)+ RNA was hybridized with a large excess of uninfected root poly(A)+ RNA. Unhybridized cDNA was selected and used to screen(More)
The comparative analysis of a large number of plant cyclins of the A/B family has recently revealed that plants possess two distinct B-type groups and three distinct A-type groups of cyclins [1]. Despite earlier uncertainties, this large-scale comparative analysis has allowed an unequivocal definition of plant cyclins into either A or B classes. We present(More)
We have isolated and sequenced a carrot cDNA and two soybean cDNAs encoding mitotic cyclin homologs. The soybean clones were derived from nearly identical cognate genes. The carrot cyclin and soybean cyclins were slightly more similar to A-type and B-type cyclins thus far defined, respectively. However, they had divergent amino acid sequences in the portion(More)
Symbiotic root nodules are beneficial to leguminous host plants; however, excessive nodulation damages the host because it interferes with the distribution of nutrients in the plant. To keep a steady balance, the nodulation programme is regulated systemically in leguminous hosts. Leguminous mutants that have lost this ability display a hypernodulating(More)
The roots of most higher plants form arbuscular mycorrhiza, an ancient, phosphate-acquiring symbiosis with fungi, whereas only four related plant orders are able to engage in the evolutionary younger nitrogen-fixing root-nodule symbiosis with bacteria. Plant symbioses with bacteria and fungi require a set of common signal transduction components that(More)
The interactions of legumes with symbiotic nitrogen-fixing bacteria cause the formation of specialized lateral root organs called root nodules. It has been postulated that this root nodule symbiosis system has recruited factors that act in early signaling pathways (common SYM genes) partly from the ancestral mycorrhizal symbiosis. However, the origins of(More)
Protein phosphorylation by the complexes of cyclin and cyclin-dependent kinase plays a key role in cell cycle progression in all eukaryotes. The amplification by polymerase chain reaction of a cyclin box from developing root nodules and root apices of soybean showed the expression of a number of different molecular species of mitotic cyclins in plant(More)
Three cyclin cDNA clones (Ntcyc25, Ntcyc27, Ntcyc29) have been isolated from tobacco (Nicotiana tabacum) using the PCR cloning method. The encoded Ntcyc cyclins were highly homologous to mitotic cyclins. In synchronized tobacco suspension cultured cells, the mRNA levels of Ntcyc25 and Ntcyc27 were detectable through S, G2 and M phases, while the Ntcyc29(More)
Induced development of a new plant organ in response to rhizobia is the most prominent manifestation of legume root-nodule symbiosis with nitrogen-fixing bacteria. Here we show that the complex root-nodule organogenic programme can be genetically deregulated to trigger de novo nodule formation in the absence of rhizobia or exogenous rhizobial signals. In an(More)
In Lotus japonicus, seven genetic loci have been identified thus far as components of a common symbiosis (Sym) pathway shared by rhizobia and arbuscular mycorrhizal fungi. We characterized the nup85 mutants (nup85-1, -2, and -3) required for both symbioses and cloned the corresponding gene. When inoculated with Glomus intraradices, the hyphae managed to(More)