Plant Genome I Conference
Town & Country Conference Center, San Diego, CA, November, 1992.
PG-I: 91pg1
IDENTIFYING NOVEL MAIZE GENES BY PARTIAL SEQUENCING OF RANDOMLY
SELECTED COMPLEMENTARY DNAS
Cindy Rixmann, Sharada Vijaychander, Anitha Chandrasekhar,
Carlyn Keith, Danee Hoang, Medha Joshi, Leah Quintana, Pisanee
Sopapan and Chris Baysdorfer, Department of Biological Sciences,
California State University, Hayward, CA 94542
We are interested in functionally identifying novel maize
genes. In this study we have partially (end) sequenced cDNAs
randomly selected from a mature leaf library. This library
contains a high proportion of unidirectionally cloned, mid to
full length cDNAs with a low representation of abundant leaf
mRNAs. A single PCR protocol is apable of amplifying most (>80%)
cDNAs. At present we have sequenced 300+ cDNAs with the
following results: previously sequenced maize cDNAs = 5%; cDNAs
provisionally identified on the basis of sequence similarity to
previously sequenced genes from organisms other than maize = 15%;
unidentified cDNAs = 80%. At this point in the screening only 2%
of the cDNAs are duplicates. Sequence and similarity data for
the provisionally identified cDNAs will be presented. About one
half of the provisionally identified cDNAs consist of
representatives of photosynthetic metabolism, glycolysis, the
citric acid cycle and protein synthesis. Approximately a fifth
encode nucleic acid binding proteins. The remaining cDNAs encode
proteins with widely diverse functions. Two thirds of the
provisionally identified cDNAs either were, or could have been,
identified entirely as a result of sequence similarity to
non-plant genes. An analysis of GenBank/EMBI., submissions
during the last two years shows that new submissions to the
databases account for a small percentage of provisionally
identified genes. We believe that the results of this and other
cDNA sequencing projects show that this approach offers a rapid
and inexpensive way to functionally identify large numbers of
plant genes.
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