Anti-CESA1 (N-terminal) polyclonal antibody

Multiple cellulose synthase (CesA) subunits assemble into plasma membrane complexes responsible for cellulose production. In the Arabidopsis (Arabidopsis thaliana) model system, we identified a novel D604N missense mutation, designated anisotropy1 (any1), in the essential primary cell wall CesA1. Most previously identified CesA1 mutants show severe constitutive or conditional phenotypes such as embryo lethality or arrest of cellulose production but any1 plants are viable and produce seeds, thus permitting the study of CesA1 function. The dwarf mutants have reduced anisotropic growth of roots, aerial organs, and trichomes. Interestingly, cellulose microfibrils were disordered only in the epidermal cells of the any1 inflorescence stem, whereas they were transverse to the growth axis in other tissues of the stem and in all elongated cell types of roots and dark-grown hypocotyls. Overall cellulose content was not altered but both cell wall crystallinity and the velocity of cellulose synthase complexes were reduced in any1. We crossed any1 with the temperature-sensitive radial swelling1-1 (rsw1-1) CesA1 mutant and observed partial complementation of the any1 phenotype in the transheterozygotes at rsw1-1's permissive temperature (21 degrees C) and full complementation by any1 of the conditional rsw1-1 root swelling phenotype at the restrictive temperature (29 degrees C). In rsw1-1 homozygotes at restrictive temperature, a striking dissociation of cellulose synthase complexes from the plasma membrane was accompanied by greatly diminished motility of intracellular cellulose synthase-containing compartments. Neither phenomenon was observed in the any1 rsw1-1 transheterozygotes, suggesting that the proteins encoded by the any1 allele replace those encoded by rsw1-1 at restrictive temperature.

Quantitative expression analysis of three cellulose synthases/subunits encoding genes (cesAl, cesAlb, and cesA2) during three fibre development stages [3, 15 and 35 days post anthesis (dpa)] in Gossypium arboreum, G. anomalum, and G. hirsutum was undertaken. Exceptionally high expression was observed in G. hirsutum at 15 dpa stage for cesAl and cesA2 (6.5 and 7.7 magnitude increase over (3 tubulin) genes, which might be responsible for longer fibre in G. hirsutum. Moderately high expression of cesAl gene was recorded in G. arboreum (at 15 dpa), and in G. anomalum (at 3 and 15 dpa). However cesAl gene expression was negligible in G. arboreum, and G. hirsutum at 3 dpa and in all three species at 35 dpa. Strong increase in expression levels of cesAlb gene (6.4 magnitude increase over (3 tubulin) was observed in G. arboreum at 15 dpa stage. Expression levels of cesAlb gene were moderate in G. hirsutum (at 3 and 15 dpa) and in G. anomalum (at 15 dpa); while its expression was low to negligible in rest of the samples. The cesA2 gene expressed at moderate to low levels at 3 dpa in G. anomalum and G. hirsutum; at 15 dpa in G. arboreum and G. anomalum; and at 35 dpa in all three species. During fibre initiation, expression of all three cellulose synthase genes was negligible in G. arboreum. In fuzzy fibred G. anomalum expression of all three ces genes was low (nil for cesAl at 3 dpa) at all the stages. These results indicate that different cellulose synthase genes, cesA1 and cesA2 (in G. hirsutum) and cesAlb (in G. arboreum) play a predominant role in fibre development.