The Cooperative Activities of CSLD2, CSLD3, and CSLD5 Are Required for Normal Arabidopsis Development

Abstract

Glycosyltransferases of the Cellulose Synthase Like D (CSLD) subfamily have been reported to be involved in tip growth and stem development in Arabidopsis. The csld2 and csld3 mutants are root hair defective and the csld5 mutant has reduced stem growth. In this study, we produced double and triple knockout mutants of CSLD2, CSLD3, and CSLD5. Unlike the single mutants and the csld2/csld3 double mutant, the csld2/csld5, csld3/csld5, and csld2/ csld3/csld5 mutants were dwarfed and showed severely reduced viability. This demonstrates that the cooperative activities of CSLD2, CSLD3, and CSLD5 are required for normal Arabidopsis development, and that they are involved in important processes besides the specialized role in tip growth. The mutant phenotypes indicate that CSLD2 and CSLD3 have overlapping functions with CSLD5 in early plant development, whereas the CSLD2 and CSLD3 proteins are non-redundant. To determine the biochemical function of CSLD proteins, we used transient expression in tobacco leaves. Microsomes containing heterologously expressed CSLD5 transferred mannose from GDP-mannose onto endogenous acceptors. The same activity was detected when CSLD2 and CSLD3 were co-expressed but not when they were expressed separately. With monosaccharides as exogenous acceptors, microsomal preparations from CSLD5-expressing plants mediated the transfer of mannose from GDP-mannose onto mannose. These results were supported by immunodetection studies that showed reduced levels of a mannan epitope in the cell walls of stem interfascicular fibers and xylem vessels of the csld2/csld3/csld5 mutant.

XAX1 from glycosyltransferase family 61 mediates xylosyltransfer to rice xylan

“…Infiltration of 4-wk-old N. benthamiana leaves was done using Agrobacterium tumefasciens strain C58 (OD = 1), following the method described in ref. 57. For details on the plasmid constructs, see SI Materials and Methods.…”

Root Hairs

“…Cellulose synthesis is required for root hair tip growth (Park et al, 2011;Galway et al, 2011), and while known components of the cellulose synthase complexes CESA3 and CESA6 are not observed in apical plasma membranes in actively growing root hair cells, a functional, fluorescently-tagged CELLULOSE SYNTHASE-LIKE PROTEIN D3 (CSLD3/KJK/RHD7: At3g03050) was enriched at the tips of growing root hairs (Park et al, 2011). Both CSLD2 (At5g16910) and CSLD3/KJK/RHD7, members of the Cellulose-Synthase-Like (CSL) super family, are required for root hair growth (Wang et al, 2001;Bernal et al, 2008;Galway et al, 2011;Yin et al, 2011;Yoo et al, 2012). While mannan synthase activity has been detected for some CSLD proteins (Yin et al, 2011), a CSLD3 chimera containing a CESA6 catalytic domain restored root hair growth in a csld3 null mutant (Park et al, 2011), raising the intriguing possibility that CSLD proteins may synthesize cellulose-like polysaccharides in tipgrowing root hair cells.…”

“…Both CSLD2 (At5g16910) and CSLD3/KJK/RHD7, members of the Cellulose-Synthase-Like (CSL) super family, are required for root hair growth (Wang et al, 2001;Bernal et al, 2008;Galway et al, 2011;Yin et al, 2011;Yoo et al, 2012). While mannan synthase activity has been detected for some CSLD proteins (Yin et al, 2011), a CSLD3 chimera containing a CESA6 catalytic domain restored root hair growth in a csld3 null mutant (Park et al, 2011), raising the intriguing possibility that CSLD proteins may synthesize cellulose-like polysaccharides in tipgrowing root hair cells.…”

Evolution of the cell wall components during terrestrialization

“…Alternatively, in the synthesis of mannans in CGA, the CslD gene can be involved, which derived from a second ancestral geneCesA [26]. The exact role of CslD in CGA is not specified, but recent studies suggest that in seed plants CslD can be responsible for glucomannan synthesis [45,79,80]. Both these alternative assumptions indicate that in CGA, the ability to synthesis of mannans was emerged independently of CslA and is a result of convergent evolution.…”