CAUT home | Background and theory | Generation of the CAUT lines
Working with the CAUT lines | Seed irradiation and sector analysis
Verification of the CAUT lines

1. Genetics.

The first step to using the CAUT lines is to cross your trait into the yellow ch-42 background. This is illustrated for a monogenic recessive trait (b). It is possible to modify the crosses to cope with dominant, lethal and/or infertile traits.

b/b CH-42/CH-42 X B/B ch-42/ch-42 (parents)
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CH-42/ch-42 B/b (F1)
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Select yellow and mutant (F2)
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b/b ch-42/ch-42

Choose one or two CAUT lines with inserts near your mutant of interest using the map and tables above and order them from NASC. You only need the map position of your mutation on either the Lister-Dean recombinant inbred map or a sequence position on the TAIR map. Grow up the mutant-ch-42 and the chosen CAUT line(s) and make several crosses between them to generate an F1. Grow this generation up and allow it to self-fertilise to generate a large F2 for irradiation. The genetics involved is illustrated below for the hypothetical recessive gene b.

b/b X B+T-DNA(CH-42)/B+T-DNA(CH-42)
All plants ch-42 homozygotes.
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b/B+T-DNA(CH-42) F1
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b/b : b/B+T-DNA(CH-42), : B+T-DNA(CH-42)/B+T-DNA(CH-42)
F2 1 yellow mutant : 2 green heterozygotes : 1green wild-type
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Irradiate bulked seeds and find yellow sectors on seedlings. (Yellow plants are disregarded and green homozygotes do not show sectors).
Sector genotype; b/0 Plant genotype b/B+T-DNA(CH-42)

As the gametes are usually set in tissue derived from the L2 layer of the floral primordium seeds set in the sector and the adjacent wild type tissue can be used to asses the genotype of L2. Seeds set in the yellow sectors should give rise to 100% yellow and phenotypically mutant plants. Seeds set in the wild type tissue should segregate and give rise to 3 green wild type plants to one yellow mutant plants. If large samples are planted a few recombinant types are typically found. Sometimes seeds which give rise to green plants are found in samples from yellow sectors, these may be due to contributions to the gametes from cells in the L1 layer of the floral primordium.