■ Introduction to Research〓 Research Area : Plant-Environmental Microbiology

Study on dynamics of Phytoplankon in environment
Our group focuses on the study of Heterosigma akashiwo, aunicellular algae that forms harmful algal bloom (commonlytermed ‘red tide’) . Algal bloom is typically caused by aberrant
propagation of a single species, resulting in its predominationin the local population. While environmental factors including
temperature and eutrophication are linked to bloom, the precise mechanism of its formation process is still obscure. We
isolated a bacterial strain, Altererythrobacter ishigakiensis,
a member of the class Alphaproteobacteria, that promotes
growth of Heterosigma akashiwo.This is the first example of
selective growth promotion of H. akashiwo by a marine bacterium, and may exemplify importance of symbiotic bacteriumon algal bloom forming process in general.

A bloom causative phytoplankton,
Heterosigma akashiwo

Study on interaction between a giant doube-stranded
DNA virus and its host〓 Assoc. Prof.
UEKI Shoko
HaV infect and lyse its host,
Heterosigma akashiwo. Thevirus was identified as a bloomterminating factor.

H. akashiwo bloom is known to be terminated by algicidal bacteria
and viruses. Heterosigma akashiwo virus (HaV) was identified as oneof such bloom-terminating factors. We completed the sequencing ofits genomes. The virual genome was characterized to be a linear double stranded DNA (dsDNA), with an estimated size of ~290 kbp. It is amember of Phycodnaviridae, one of the viral families regarded as “giantdsDNA viruses” that possess genomes larger than several hundred-kbp
in size.
We are particularly interested in studying about the infection mechanismof HaV at cellular and molecular level. The study will provide insights
into infection strategies of a giant dsDNA virus, and the molecular mechanism of a major environmental phenomenon, bloom termination.

〓 Research Area : Plant Diversity Analysis

Preservation and application of genetic and genomic
resources in barley
Ca. 15,000 accessions of wild and cultivated barleys
and a wide range of experimental strains are preserved with a support from the National Bioresrouce
Project. Genomic libraries and extensive cDNA resources have been developed for genomic analysis ofbarley which contributed to estimate gene regions on
the draft barley genome sequence published in 2012.
These genetic and genomic resources are used toidentify agriculturally important genes on barley genome. We also found that barley and diploid wheatshared the same genomic structure and barley canbe used as a diploid model of the Triticeae species,
including wheat, barley and rye.

Gene isolation in barley〓 Prof.
SATO Kazuhiro

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The study focuses on isolation and characterization ofgenes controlling industrially important traits using thegenome diversity of barley. A recent example is a genecorresponding for barley seed dormancy (Qsd1), whichis associated with pre-harvest sprouting and malting for
brewing beer. Our analysis using a wild barley accession
harboring a strong grain dormancy revealed novel insight
into the genetic mechanism regulation grain dormancy inbarley (Sato et al. 2016 Nat. Commun.).
The orthologous genes are also existed in wheat genomes which will be important to control seed dormancy
in wheat.