Mutant Name: cyt1 (emb101)

Gene Name CYT1
Protein Name GDP-mannose pyrophosphorylase
Mutagen T-DNA
Category forward genetics
Organism Arabidopsis thaliana
Ecotype Ws
Donor
General Description 1.Mutants were embryonic lethal resulting from both a disruption of cytokinesis and a failure to synthesize a normal cell wall.
2.Mutants showed radial swelling, excessive cell-wall thickenings, and inappropriate callose accumulation.
3.The cyt1-1 allele had a point mutation in codon 89 (CCT to CTT) resulting in a change from proline to leucine. In the cyt1-2 allele a single nucleotide was inserted in codon 306 (TCG to TTCG) causing a 1 frameshift and at the same time disrupting an XhoI site.
4.A weak mutation in the same gene, vtc1, was previously isolated because of its low content of ascorbic acid.
Organ Specificity CYT1 transcripts were about 1.5 kb in size and expressed in all tissues examined (seedlings, roots, leaves, stems, inflorescences)
Impact on Wall 1. thickened cell walls resulting from massive accumulation of PAS-positive polysaccharides.
2. Inappropriate callose formation in both intact and incomplete cell walls;
3. diffuse localization of unesterified pectins throughout the cell wall.
Impact on Sugar Composition 1.The cell walls of cyt1-1 embryos contained reduced amounts of mannose (35% of wild-type) and fucose (45% of wild-type). Other noticeable differences were elevated levels of rhamnose (152% of wild-type) and xylose (122% of wild-type).
2.Mutant cyt1 embryos are deficient in N-glycosylation . Most notably, they show a 5-fold decrease in cellulose content.
3.excessive callose accumulation in root.
Reference 1.Todd C. Nickle and David W. Meinke.A cytokinesis-defective mutant of Arabidopsis ( cyt1 ) characterized by embryonic lethality, incomplete cell walls, and excessive callose accumulation.The Plant Journal.(1998)15(3),321-332

2.Lukowitz W, Nickle TC, Meinke DW, Last RL, Conklin PL, Somerville CR. Arabidopsis cyt1 mutants are deficient in a mannose-1-phosphate guanylyltransferase and point to a requirement of N-linked glycosylation for cellulose biosynthesis.Proc Natl Acad Sci U S A. 2001 Feb 27;98(5):2262-7.