I am working with a Sail T-DNA insertion line, located in an intron of a gene;
in the original background (Col3qrt1) I could select homozygous plants, based
on segregation ratio (3:1) and PCR (using genomic DNA with gene specific primers and the left
border primer). Next,I did repeated backcrosses of homozygous mutant with wild type Col 0 plants.
The following pattern occured after the 4th backcross:
-the seeds produced from the backcross segregate ,as expected, 1:1 and carry the T-DNA insert (confirmed by PCR
on genomic DNA)
-after self-pollination of the heterozygous plants resulted from backcross, the seeds segregate as expected 3:1
BUT by PCR all the seed from an individual silique are having only the gene specific band but NO left border
(I used positive and negative controls for primers and genomic template);
-reciprocal crosses showed no gametophytic defect;
-in the original background(Col3qrt1) it is possible to isolate homozygous plants;
-segregation indicates a single insert and no embryo or gametophytic defects
-backcrossing to Col 0 produces as expected heterozygous progeny
-BUT after selfing of the heterozygous plants in Col 0 background, neither homozygous nor heterozygous are identified.
I would appreciate any suggestion/ ideas to clarify this problem!
Arabidopsis T-DNA insert
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