O-GLYCOSILATED CELL WALL PROTEINS ARE ESSENTIAL IN ROOT HAIR GROWTH

SILVIA M. VELASQUEZ; JAVIER GLOAZZO DOROSZ; JUAN SALGADO SALTER; MARTINIANO M. RICARDI; NORBERTO D. IUSEM; JOSE M. ESTEVEZ

San Luis

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigacion dne Bioquimica y Biologia Molecular

Plant cell walls contain abundant hydroxyproline glycoproteins, which include Extensins (EXTs) and Arabinogalactan-proteins (AGPs). These proteins undergo posttranslational modifications such as firstly the addition of an hidroxyl group on proline residues, carried out by Prolyl 4-hydroxylases (P4Hs) and secondly, the addition of arabinoses and/or galactoses, done by glycosyltransferases, finally these modified proteins form a covalent network. We focused on root hairs were we found 3 p4hs mutants with distinct short root hair phenotype: p4h2, p4h5 and p4h13. Through GFP-tagged P4Hs we were able to determine an ER and partially Golgi apparatus sub-cellular localization. This same root hair phenotype was mimicked when roots were treated with either ethyl-3,4-dihydroxybenzoate ( binds to the active site of P4Hs), or α, α-dipyridyl (chelates the cofactor Fe2+). The Wt phenotype in these p4hs mutants was restored with P4Hs driven by either their own promoter or the strong 35SCaMV promoter. The p4h2-p4h5 double mutant had similar root hairs than that of the single mutant p4h5, suggesting a functional overlap. On the contrary, the double mutant p4h2-p4h13 had much shorter root hairs suggesting differences in specificity. We also identified several exts mutants with short root hair phenotype. Our results help to better understand the importance of O-glycosylation in polarized growth.