Bioengineering

Japanese

Research

Isolation and improvement of elements involved in high expression of transgene

 Gene expression is controlled by several processes such as transcription, post-transcription, and translation. In order to efficiently express the introduced useful genes in plants, it is necessary to optimize each process. Therefore, we are analyzing sequences related to the efficiency of control processes such as core promoter, terminator, splicing site, 5'UTR and 3'UTR. Through these analyzes, we are isolating and improving the sequence elements involved in high expression. We also aim to provide the results to various companies to produce useful proteins such as vaccine proteins and growth hormones in plants (Fig. 1)

Fig.1 Flow of gene expression

 In order to optimize each step of gene expression, we are analyzing each regulatory process in detail.


Sequence optimization of expression system

 The efficiency of various control processes is determined by the sequence. Therefore, elucidation of the relationship between efficiency and sequence makes it possible to design a completely new sequence with excellent efficiency (Fig. 2). So far, we have succeeded in dramatically improving the mRNA translation efficiency by optimization of the 5'UTR sequence. Our current goal is optimization of the entire sequence of expression systems to maximize the efficiency of any control process.

Fig.2 Optimization of expression system

 We are elucidating the determinants of efficiency of control processes, and are optimizing the sequence of gene expression systems.


Phenotypic and genetic polymorphisms in plants

 Nucleic and phenotypic polymorphisms are maintained even in a species. Especially for plant species, which do not move from the place to another, natural selections strongly affect to its genotype and phenotype in the process of local adaptation. Therefore, these polymorphisms are important to persistence and migration of the species. In addition to wild plants, intraspecific polymorphisms are also important in agricultural varieties. There are various polymorphisms in agricultural varieties and these polymorphisms could be keys of breeding for their specific characteristics including tastes and disease resistances.

Fig.3 Flowering time variation in a species

 Putting both of phenotypic polymorphisms and genome-wide nucleotide variation, which can be gathered by next-generation sequencing technology, into association analyses, related gene regions can be detect. We are focusing on traits related to the plant reproductive success, for example, flowering time and annual/perennial, because these traits are directly related to biodiversity and breeding.

Fig.4 Genotype-Phenotype association analysis