ARABIDOPSIS POLLEN EXTENSINS LRX ARE REQUIRED FOR MAINTAINING CELL WALL INTEGRITY DURING POLLEN TUBE GROWTH

SEDE, ANA ROCIO; BORASSI, CECILIA; WENGIER, D.; ESTEVEZ, JOSE; JORGE MUSCHIETTI

Congreso; XXII Reunión Argentina Fisiología Vegetal; 2018

ARABIDOPSIS POLLEN EXTENSINS LRX ARE REQUIRED FOR MAINTAINING CELL WALL INTEGRITY DURING POLLEN TUBE GROWTHAna Rocio Sede (1), Cecilia Borassi (2), Diego Wengier (1), José Manuel Estevez (2), Jorge PrometeoMuschietti (1) (1) INGEBI, (2) Fundacion Instituto Leloir.Polarized growth of pollen tubes is an oscillatory mechanism that involves a tight coordination of Ca2+ ions and Reactiv Oxygen Species (ROS) with high trafficking of vesicles to the tip where a constant remodeling of the cell wall occurs. During this process, it is crucial the regulatory and structural role of the cell wall and the presence of glycoproteins and homogalacturonans which are involved in cell wall crosslinking contributing to maintain its proper assembly. Here, we studied the function of 4 pollen specific LRX8-11 (Leucine-rich Repeat Extensin-like) proteins which belong to the HRGP (Hydroxyproline-rich glycoprotein) family in Arabidopsis thaliana. These chimeric proteins have an N-terminal LRR (Leucine-rich repeat) domain and a C-terminal extensin (EXT)-like domain with Ser-Pro repetitions possibly glycosylated. The analysis of simple, double and one triple LRX knock-out mutants revealed an important reduction in pollen germination rates, a skewed segregation ratio due to defects in pollen transmission. We also found severe abnormalities in pollen tube morphology with the concomitant heterologous/abnormal? deposition of pectin and callose at the cell wall. All together these results suggest that pollen LRX(8-11) are necessary to maintain cell wall integrity and prevent tip bursting during pollen germination and polarized growth of pollen tubes.