To elucidate the cellular functions of phospholipase A2 in plants, an Arabidopsis cDNA encoding a secretory low molecular weight phospholipase A2 (AtsPLA2β) was isolated. Phenotype analyses of transgenic plants showed that overexpression of AtsPLA 2β promotes cell elongation, resulting in prolonged leaf petioles and inflorescence stems, whereas RNA interference-mediated silencing of AtsPLA2β expression retards cell elongation, resulting in shortened leaf petioles and stems. AtsPLA2β is expressed in the cortical, vascular, and endodermal cells of the actively growing tissues of inflorescence stems and hypocotyls. AtsPLA2β then is secreted into the extracellular spaces, where signaling for cell wall acidification is thought to occur. AtsPLA2β-overexpressing or -silenced transgenic plants showed altered gravitropism in inflorescence stems and hypocotyls. AtsPLA2β expression is induced rapidly by auxin treatment and in the curving regions of inflorescence stems undergoing the gravitropic response. These results suggest that AtsPLA2β regulates the process of cell elongation and plays important roles in shoot gravitropism by mediating auxin-induced cell elongation.
ASJC Scopus subject areas
- Plant Science
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology