In higher plants, cellulose is synthesized at the plasma membrane by the cellulose synthase (CESA) complex. The catalytic core of the complex is believed to be composed of three types of CESA subunits. Indirect evidence suggests that the complex associated with primary wall cellulose deposition consists of CESA1, -3, and -6 in Arabidopsis thaliana. However, phenotypes associated with mutations in two of these genes, CESA1 and -6, suggest unequal contribution by the different CESAs to overall enzymatic activity of the complex. We present evidence that the primary complex requires three unique types of components, CESA1-, CESA3-, and CESA6-related, for activity. Removal of any of these components results in gametophytic lethality due to pollen defects, demonstrating that primary-wall cellulose synthesis is necessary for pollen development. We also show that the CESA6-related CESAs are partially functionally redundant.gametophytic lethal ͉ isoforms ͉ pollen ͉ cellulose synthesis ͉ mutant

A series of gene constructs encoding synthetic glycomodule peptides with N-terminal signal sequences and C-terminal green fluorescent proteins were expressed in transgenic Arabidopsis (Arabidopsis thaliana) under the control of the 35S promoter. The synthetic glycomodule peptides were composed of repetitive proline-containing motifs that have been previously found to be substrates for prolyl hydroxylases and subsequent O-glycosylation of the hydroxyproline residues. All of the constructs were secreted in aerial tissues, but not in roots. The amount of hydroxylation and glycosylation of the various constructs varied depending on the tissue. Also, accumulation of the proteins exhibited a high degree of cell-type specificity within various tissues due to posttranscriptional effects. The observations reveal a high level of complexity in the synthesis, secretion, and turnover of the glycoproteins.