Reply to Mapping a gene . . .

[Robert F. Whittier]

In response to Richard Timmer's request for suggestions 
on assigning cDNAs to Arabidopsis chromosomes . . .

     Since estimates for the Arabidopsis haploid genome size run 
from 7 x 10*7 to 1.4 x 10*8, one can expect chromosomes in the 
size range of 20 Mbp.  I have not heard of anybody succeeding in 
separating chromosomes of this size by pulse field electrophoresis 
yet.  Until physical mapping proceeds to the point that contig 
pools are available for each chromosome, I know of no alternative 
but to try to detect an RFLP with the cDNA as probe, and then test 
the inheritance of RFLPs among Recombinant Inbred lines.  One set 
of such lines (between the Landsberg and Wassilewskija ecotypes) 
was developed at DuPont, and they have already published data based 
upon these strains (PNAS 89 No.4 pp 1477-1481).  Another set of 
RI lines, this one between Columbia and Landsberg, is under 
development in England.  
     Obviously this method is more work than what you had in mind, 
although more precise mapping information will also fall out of it.
Maybe somebody else on the network can make a more efficient 
suggestion, or is willing to wager a guess how soon chromosome 
contig pools will be a reality.

Bob Whittier
Mitsui Plant Biotechnology Research Institute
Tsukuba, Japan