NASC

Donated by

• Ian Furner Department of Genetics, University of Cambridge

Click here to view all 16 of these lines.

Description

Arabidopsis lines homozygous for transgene inserts silencing the CH-42 gene and also for second site mutations suppressing the CH-42 silencing phenotypes

The CH-42 gene of Arabidopsis codes for a subunit of magnesium chelatase which is required for the biosynthesis of the green photosynthetic pigment chlorophyll (Koncz et al., 1990). Homozygous mutants of this locus are typically albino or yellow in phenotype and are recessive to the dominant wild-type allele in heterozygotes (Furner et al., 2008). A wild-type copy of the genomic copy CH-42 gene supplied on a T-DNA somewhere in the genome is usually sufficient to complement the ch-42 mutation at the normal locus (Furner et al., 2008). Experiments with X-irradiated hemizygotes suggest that small sectors of ch-42 tissue have a cell autonomous yellow phenotype (Furner et al., 1996). Silencing of the CH-42 gene should result in decreases in magnesium chelatase and chlorophyll and increases in the amount of yellow chlorophyll deficient tissue.

Hairpin constructs directed against the 3’ end of the CH-42 gene result in a dominant yellow phenotype (Daxinger et al., 2008). The Ubi42 line contains an inverted repeat construct containing the 3’ end of the CH-42 gene driven by the maize ubiquitin (Ubi-1) promoter (Christensen and Quail, 1996). The yellow phenotype is coded by a single insert and behaves as a co-dominant trait, homozygous plants are yellow and hemizygotes are pale green. The Gld line contains a single insertion site with 10-20 T-DNA copies of a T-DNA containing the genomic copy of the CH-42 gene. Plants homozygous for this insert are yellow with rare variegated plants. Hemizygotes produced by outcrosses to non-transgenic plants are highly variegated. A similar pattern of outcross hemizygote variegation has been reported with a complex insert containing duplicate copies of the genomic copy of the chalcone synthases gene (Davies et al., 1997).

A scheme was devised to test the effect of a variety of silencing related mutants on the phenotypes coded by the Gld and Ubi42 inserts. Eleven mutations were identified that each of which acts as a recessive second-site suppressors of the Gld insert phenotype. One recessive and one dominant second-site suppressor of the Ubi42 insert were also identified. The appropriate double and triple homozygotes were identified in segregating families and have been donated to the stock centre. The genotypes of the lines are as indicated. The Gld and Ubi42 lines are in The Landsberg er background. The silencing insert-suppressor lines are in a mixed Columbia/ Landsberg er background. Both the Ubi42 and Gld homozygous plants are yellow and the silencing insert-suppressor double homozygotes are greener. The yellow homozygous Ubi42 and Gld plants grow better at low light intensities and the greener insert hemizygotes are healthier than the corresponding homozygotes. The table lists the genotypes of the homozygous seeds the form is mutant insert for example ago4-1 Gld.

Sets in this collection

Nasc code	Description	Stock contents
N799439	Set of 16 Furner, Engledow, Sheikh, Bull, Hunter, Bottley and Ellis lines	View set contents

References

• Furner I.J., et al. 2008. The CAUT lines; a novel resource for studies of cell autonomy in Arabidopsis. The Plant Journal 53(4): 645-660. PMID. 18269574.
• Christensen, A.H. & Quail, P.H. 1996. Ubiquitin promoter-based vectors for high-level expression of selectable and/or screenable marker genes in monocotyledonous plants. Transgenic research 5(3):213-8. PMID. 8673150.
• Daxinger, L. et al. 2007. Unexpected silencing effects from T-DNA tags in Arabidopsis. TRENDS in Plant Science 13(1):4-6.Link to Article.
• Furner, I.J. 1996. Cell fate in the development of the Arabidopsis flower. Plant Journal 10(4):645-54.PMID. 8998500.
• Koncz, C. et al. 1990. Isolation of a gene encoding a novel chloroplast protein by T-DNA tagging in Arabidopsis thaliana. EMBO Journal 9(5):1337-46.PMID. 2158442.