A mutant of Arabidopsis thaliana displaying altered patterns of cellulose deposition

Summary A homozygous recessive mutant of Arabidopsis thaliana has been selected which displays altered patterns of cellulose deposition. The mutant was selected because leaf and stem trichomes lacked the strong birefringence under polarized light which is characteristic of plant cells which contain highly ordered cellulose in their secondary cell walls. Compared with wild‐type A. thaliana, this mutant (designated tbr for trichome birefringence) also displays reduced birefringence in the xylem of the leaf. Direct chemical analyses of root, stem, and leaf tissues, including isolated leaf trichomes, support the conclusion that tbr is impaired in its ability to deposit secondary wall cellulose in specific cell types, most notably in trichomes where the secondary wall appears to be totally absent. Altered patterns of wound‐induced callose deposition in trichomes and surrounding cells is another trait which also co‐segregates with the tbr mutation.