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Isolation
of useful genes and clarification of their function
In the 2nd stage of the rice genome project that was initiated in fiscal
1997, a new project focusing on the analysis of the genome function was
launched in addition to the existing genome sequencing project. The visible
results of such efforts, reinforced by the Millennium budget granted in
fiscal 2000, will be the possibility of acquiring patents on many genes.
The following is a summary of activities in each area (indicated as abbreviated
titles) and part of the results for fiscal 2001.
1."Map-based cloning"(starting from 1998)
Isolation
of useful genes and QTL analysis of important traits have been actively made by
using the precise linkage map produced in the first phase of the project,
various DNA markers, genome DNA libraries and physical maps. A gene (qSH-1) that
controls the shedding habit of rice and a gene (LAX) that adjusts the branching
of rice ears have been isolated.
2."Mutant panel" (from 1998)
With
40,000 gene-knockout rice mutant systems produced, genes have been isolated by
using three different types of analytical approach (analysis of genes that have
caused mutations; PCR screening of specific knockout systems and evaluation of
traits; and analysis of sequences contiguous to the sites of transposon
insertion and evaluation of traits). Genes such as Msp1, thought to influence
the differentiation of productive cells, have been isolated.
3."Microarrays" (from 1999)
Two
kinds of microarray are used to investigate changes in the expression of nearly
10,000 genes in total and to discover genes that respond to various types of
stress and emerge specific to each stage of their development and
differentiation. Each of these microarrays is a small glass sheet with 1,265
and 8,897 EST (fragments of cDNA) selected from among those isolated in the
first phase of the rice genome project. Genes such as CIGR1, which are
inducible in response to a pathogenic infection (an elicitor) have already been
isolated.
4."Proteomes" (from 2000)
This
research project consists of a comprehensive analysis of proteins that make up
each tissue of the rice organism, an analysis of the high-order structure of
proteins and an information engineering-based estimate of their functions from
the high-order structure. Protein-coding genes subject to specific expression
are being isolated in parallel with the analysis of the post-translational
modification of proteins. Genes such as RO-292, which is expressed specifically
in the root in response to salinity and desiccation, have been isolated.
5."Full-length cDNA Library" (from 2000)
The project is aimed at isolating an estimated 30,000 full-length cDNAs
that contain information on regions related to the synthesis of proteins
in all rice genes (estimated to total 30,000) and analyzing their complete
sequences. Funded by the Bio-oriented Technology Research Advancement Institution,
the project is under the joint administration of the National Institute
of Agrobiological Sciences, the Institute of Physical and Chemical Research,
and the Foundation for Advancement of International Science. About 28,000
genes are expected to be revealed during fiscal 2001. It is therefore likely
that the target will be achieved during fiscal 2002?earlier than scheduled.
With the cDNA expected to contribute greatly to the functional analysis
of genes, plans are being worked out to use them in new projects.
(Kenichi HIGO, NIAS)
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