Mutant Name: korrigan (kor)

Gene Name KOR1
Protein Name beta,1-4 endoglucanase
Mutagen T-DNA
Category forward genetics
Organism Arabidopsis thaliana
Ecotype Ws
Donor
General Description 1. Korrigan is an allele of irx2 with a T-DNA insertion 200 bp upstream of the initiation codon of KOR.
2.This mutant has an extreme dwarf phenotype with pronounced architectural alterations in the primary cell wall.
3.KOR gene encodes a primarily plasma membrane-anchored member of the EGase family, which is highly conserved between mono- and dicotyledonous plants
Organ Specificity 1. kor shows a defect in the elongation of non-tip-growing cells.
2. KOR mRNA was found in all organs examined(7-day-old light-grown seedlings, leaves, stems, flowers, siliques, roots)with the highest levels in stems and roots,and the lowest in siliques. In the developing dark-grown hypocotyl, mRNA levels were correlated with rapid cell elongation.
3. Among plant growth factors involved in the control of hypocotyl elongation (auxin, gibberellins and ethylene), none significantly influenced KOR-mRNA levels. However, reduced KOR-mRNA levels were observed in det2, a mutant deficient for brassinosteroids.
Impact on Wall 1. Fixed mutant walls were thicker than those of the wild-type.
2. The extraction of the wall with CDTA, a treatment that selectively removes Ca2 -linked acidic pectins, caused a separation of the innermost layers from the rest of the wall, which was never observed in wild-type walls.
Impact on Sugar Composition 1. Polysaccharides were deposited in an irregular fashion in both external epidermal and cortical cell walls.
2. The kor mutant has indirect change of pectin composition in promary cell wall: a marked increase in homogalacturonan epitopes, a decrease in rhamnogalacturonan epitopes and cellobiohydrolase I-gold labelling.
Reference 1.Nicol F, His I, Jauneau A, Vernhettes S, Canut H, Hofte H. A plasma membrane-bound putative endo-1,4-beta-D-glucanase is required for normal wall assembly and cell elongation in Arabidopsis. EMBO J. 1998 Oct 1;17(19):5563-76.

2.His I, Driouich A, Nicol F, Jauneau A, Hofte H. Altered pectin composition in primary cell walls of korrigan, a dwarf mutant of Arabidopsis deficient in a membrane-bound endo-1,4-beta-glucanase. Planta. 2001 Feb;212(3):348-58.

3.Szyjanowicz PM, McKinnon I, Taylor NG, Gardiner J, Jarvis MC, Turner SR. The irregular xylem 2 mutant is an allele of korrigan that affects the secondary cell wall of Arabidopsis thaliana. Plant J. 2004 Mar;37(5):730-40.

4.Turner, S.R. and Somerville, C.R. (1997) Collapsed xylem phenotype of Arabidopsis identifies mutants deficient in cellulose deposition in the secondary cell wall. Plant Cell, 9, 689-701.