Mutation in a gene required for pectin synthesis led to PCB resistance.

<p>(a) A screened <i>pcb1</i> mutant resistant to the bleach effects of 10 µM PCB 18. Six-d-old Arabidopsis seedlings were transferred to plates containing 10 µM PCB 18 and grown for 2 weeks. (b) Map-based cloning of <i>pcb1</i> revealed it was a new allele of <i>quasimodo1</i> and had a G- to A- transition in its second exon. The positions of each locus in chromosome 3 of Arabidopsis and the recombinants in relation to each marker are shown. (c) The PCB1/QUA1 protein had a transmenbrane (TM) domain in the N-terminus and a glycosyltransferase 8 (GT8) domain in the C-terminus, while <i>pcb1</i> had a mutation in the conserved GT8 domain. (d) The arabinose (Ara), xylose (Xyl), and galactose (Gal) contents in 12-d-old seedlings of <i>pcb1</i> were comparable to the wild-type, but the GalA content showed a ∼20% reduction.