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Current position
Professor, RSBS,
ANU
Research interests
Genetic dissection of cell wall structure and properties
The carbohydrates and
proteins of the cell wall form cages that surround all plant cells.
The crystalline carbohydrate cellulose is a key component of those
walls and is familiar to us as the key component of cotton and
wood fibres. We use mutants of the model plant Arabidopsis
(Baskin et al 1992 Aust J Plant Physiol 19, 427-438) to understand
how plants make the major carbohydrates of their walls and how
the properties of those walls control the shape into which plant
organs grow. In our mutants, we can switch roots from growing
longitudinally to growing radially by raising the temperature.
By analysing the carbohydrates in the mutants and the ultrastructure
of their walls, we determine what changes alter the direction
of growth; by cloning the mutated gene, we identify the genes
making those carbohydrates. One mutant switches off cellulose
production because one nucleotide has been altered in the gene
making the catalytic subunit of cellulose synthase (Arioli et
al 1998 Science 179, 717-720). Other genes where mutations impair
cellulose production encode an endo-1,4-beta-glucanase
(Lane et al 2001 Plant Physiology 126, 278-288) and glucosidase
lI, an ER enzyme involved in the N-glycosylation/quality control
pathway (Burn et al 2002, Plant Journal 32,949-960). We are also
working to use our ability to change cell wall properties to produce
improved cotton and wood fibres and, through a collaboration with
the ANU Engineering Department, to model the mechanical properties
of the plant cell wall.
Selected Publications
Howles PA, Birch RJ, Collings DA, Gebbie LK, Hurley UA, Hocart CH, Arioli T, Williamson RE (2006) A mutation in an Arabidopsis ribose-5-phosphate isomerase reduces cellulose synthesis and is rescued by exogenous uridine. Plant Journal 48, 606-618.
Wang J, Howles PA, Cork AH, Birch RJ, Williamson RE (2006) Chimeric proteins suggest that the catalytic and/or C-terminal domains give CesA1 and CesA3 access to their specific sites in the cellulose synthase of primary walls. Plant Physiology 142, 685-695.
Gebbie LK, Burn JE, Hocart CH, Williamson RE. (2005) Genes encoding ADP-ribosylation factors in Arabidopsis thaliana L. Heyn.; genome analysis and antisense suppression. Journal of Experimental Botany 56, 1079-1091.
Himmelspach R, Williamson RE, Wasteneys GO. (2003) Cellulose microfibril alignment recovers from DCB-induced disruption despite microtubule disorganisation. Plant Journal 36, 565-575
Sugimoto K, Himmelspach R, Williamson RE, Wasteneys GO. (2003) Mutation or drug-dependent microtubule disruption causes radial swelling without altering parallel cellulose microfibril deposition in Arabidopsis thaliana root cells. Plant Cell 15, 1414-1429.
Burn JE, Hurley UA, Birch RJ, Arioli T, Cork A, Williamson RE (2002). The cellulose-deficient Arabidopsis mutant rsw3 is defective in a gene encoding a putative glucosidase II, an enzyme processing N-glycans during ER quality control. Plant Journal 32, 949-960
Williamson RE, Burn JE, Hocart CH. (2002) Towards the mechanism of cellulose synthesis. Trends in Plant Science 7, 461-467.
Lane DR, Wiedemeier A, Peng L, Höfte H, Vernhettes S, Desprez T, Hocart CH, Birch RJ, Baskin TI, Burn JE, Arioli T, Betzner AS, Williamson RE (2001). Temperature sensitive alleles of RSW2 link the KORRIGAN endo-1,4-ß-glucanase to cellulose synthesis and cytokinesis in Arabidopsis thaliana. Plant Physiology 126, 278-288.
Sugimoto K, Williamson RE, Wasteneys GO (2001). Wall architecture in the cellulose-deficient rsw1 mutant of Arabidopsis thaliana: microfibrils but not microtubules lose their transverse alignment before microfibrils become unrecognisable in the mitotic and elongation zones of roots. Protoplasma 215, 172-183.
Williamson RE, Burn JE, Birch R, Baskin TI, Arioli T, Betzner AS, Cork A (2001). Morphology of rsw1, a cellulose-deficient mutant of Arabidopsis thaliana. Protoplasma 215, 116-127.
Arioli T, Peng L, Betzner AS, Burn J, Wittke W, Herth W, Camilleri
C, Hofte H, Plazinski J, Birch R, Cork A, Glover J, Redmond J,
Williamson RE (1998) Molecular analysis of cellulose biosynthesis
in Arabidopsis thaliana. Science 179, 717-720.
Dr Charles Hocart
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