研究概要/Research

Genome sequence is the most important infrastructure for modern biological researches. We have laid the foundation for comparative genomic analyses in this crop through genomic sequencing of common wheat (Triticum aestivum) cultivars. We will be able to carry out various breeding and molecular biological researches on wheat, just like any other crops or model plants. Reflecting a 100-years history of modern wheat research, a pile of knowledge about interesting biological phenomena such as polyploid evolution and genome dynamics is accumulated in wheat. Why don’t you start wheat research now?
Prior to modern breeding, there were landraces cultivated in small region around the world. Wheat lines that have dispersed eastward from their origin are not extensively used for modern breeding. We wish to contribute to world wheat breeding through evaluation of the genetic diversity of the world's landraces, and generation of a set of experimental strains that enables genetic analysis of important agronomic traits of East Asian wheat.

Plant breeding is the planned genetic improvement of plants. In breeding, human beings have applied selective pressure to living organisms instead of nature. Selection pressure is on the phenotype of the organism. Phenotypic variation is generally understood by sum of variations given by genotype, environmental factors and their interactions. Plant breeding mainly manipulates genotypes of organisms to achieve the ideal phenotype as a crop.
We are tackling the following issues to improve the efficiency of breeding. (1) We are conducting research on the mechanism of recombination with the aim of artificially controlling the recombination frequency. (2) We are addressing molecular function of the　genes that causes a structural rearrangement of the chromosomes in wheat. (3) To evaluate the contribution of genotype to phenotype correctly, we are collaborating with other research groups to develop methodology to accurately describe the phenotype using modern technologies.

Soybean (Glycine max) is one of the most important crops in the world. The use of legumes in biofuel production will further increase the economic impact of soybean. Enhancing the efficiency of biological nitrogen fixation by improving legume-rhizobium symbiotic relationships is one of the most efficient ways, as it has a lower cost and smaller environmental impact, to increase the productivity of legumes, including soybean and to continue sustainable agriculture. Soybean plants establish symbiotic relationships with soil rhizobia to fix atmospheric nitrogen. Understanding this genetic interrelationship is important for developing strategies to improve the agronomic potential of root nodule symbiosis in agriculture. QTL analysis of soybean recombinant inbred lines (RILs) in three different field soils and identified the indigenous rhizobia nodulating each line identified one QTL region with a highly significant additive effect.

Almost all of vegetables and fruits in the grocery stores are improved varieties called “cultivated varieties”, which possess better appearance, taste, and yield than wild races. For example, wild rice will sow its seeds after ripening by shattering, but this character is already lost in the cultivated varieties for it decreases the yield. In addition, rice yield has been highly increased by the modification of plant height, leaf angle, and number of tillers. The genetic mechanisms that control these crop developments are not fully understood, thus we are trying to reveal the function of genes involved in crop development by utilizing induced mutation and/or genome edition.
Just like animal grows from baby to adult, plant developmental phase also transits from juvenile to adult phase, accompanied by a variety of morphological and physiological alteration. It is well known that two microRNAs, miR156 and miR172, play pivotal roles in this phase transition, and we newly found novel regulators of phase transition in rice. We hope to deepen the understanding of juvenile and adult phase in crops by analyzing these regulators.