O-glycosylated cell wall proteins are essential in root hair growth

VELASQUEZ SM, RICARDI MM, DOROSZ JG, FERNANDEZ PV, NADRA AD, POL-FACHIN L, EGELUND J, GILLE S, HARHOLT J, CIANCIA M, VERLI H, PAULY M, BACIC A, OLSEN CE, ULVSKOV P, PETERSEN BL, SOMERVILLE C, IUSEM ND, ESTEVEZ JM.

SCIENCE

AMER ASSOC ADVANCEMENT SCIENCE

Año: 2011 p. 1401 - 1403

0036-8075

Root hairs are single cells that develop by tip growth and are specialized in the absorption of nutrients. Their cell walls are composed of polysaccharides and hydroxyproline-rich glycoproteins (HRGPs) that include extensins (EXTs) and arabinogalactan-proteins (AGPs). Proline hydroxylation, an early posttranslational modification of HRGPs that is catalyzed by prolyl 4-hydroxylases (P4Hs), defines the subsequent O-glycosylation sites in EXTs (which are mainly arabinosylated) and AGPs (which are mainly arabinogalactosylated). We explored the biological function of P4Hs, arabinosyltransferases, and EXTs in root hair cell growth. Biochemical inhibition or genetic disruption resulted in the blockage of polarized growth in root hairs and reduced arabinosylation of EXTs. Our results demonstrate that correct O-glycosylation on EXTs is essential for cell-wall self-assembly and, hence, root hair elongation in Arabidopsis thaliana.