STUDY OF RALF4/19 PEPTIDES ROLE DURING POLLEN TUBE GROWTH IN ARABIDOPSIS THALIANA

SOMOZA, SOFÍA C.; JORGE MUSCHIETTI; MECCHIA, MARTIN

Congreso; XXII Reunión Argentina Fisiología Vegetal; 2018

STUDY OF RALF4/19 PEPTIDES ROLE DURING POLLEN TUBE GROWTH IN ARABIDOPSIS THALIANASofía C. Somoza (1), Martin A. Mecchia (2), Jorge P. Muschietti (1)(1) Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI). (2) Centro de Investigación Agrigenómica UAB, Barcelona, SpainPolarized cell growth involves the expansion of one of its ends, making cell elongation in a single direction. In plants, this process occurs in growing pollen tubes root hairs and cotton fibers. Pollen tube growth is a process regulated by cytoskeletal reorganization, vesicular movement, Ca2+ signaling and reactive oxygen species (ROS). Because plant cells possess a rigid cell wall, regulation of its integrity is also essential for a correct polarized growth. RAPID ALKALINIZATION FACTORs (RALFs) are secreted peptides relevant for transducing extracellular signals to the inside of the cell. Spread throughout the plant kingdom, with 36 members in Arabidopsis thaliana, RALFs regulate developmental and physiological processes. Eight Arabidopsis RALFs are expressed in pollen. We focused our study on two of them, RALF4 and RALF19, closely related to each other. We found that RALF4 and RALF19 are required to maintain proper pollen tube growth. We also showed that LEUCINE-REICH EXTENSIN (LRX) proteins directly interact with RALF4 and RALF19, probably regulating changes in the integrity of pollen tube cell wall and transmitting this signal to the interior of the cell. Understanding of how the pollen RALF and LRX proteins regulate pollen tube growth will shed some light about how plant reproduction works.