Halotropism requires phospholipase Dζ1‐mediated modulation of cellular polarity of auxin transport carriers ($) (Plant Cell Environ)

Phospholipase D (PLD) enzymes cleave phosopholipds to release phosphatidic acid (PA), which is a signal that affects membrane dynamics. Previous studies have indicated a role for PLD and PA in root responses to osmotic and salt stress, but as the Arabidopsis genome has 12 genes encoding PLD questions remain about their specific functions. Korver et al. have investigated the role of PLDζ1 (zeta1), which has sequence features resembling mammalian PLDs. They found that knockout mutants show delayed halotropism (bending away from salt) and an exaggerated gravitropic response, as well as abnormalities in the redistribution of the auxin transporter PIN2. Osmotic stress induced membrane structures (OSIMS) that occur shortly after osmotic or salt stress have a prolonged presence in the pldζ1 mutant. The authors conclude that the delayed halotropism response of the pldζ1 mutant is a consequence of reduced auxin asymmetry arising from altered PIN2 distribution. (Summary by Mary Williams) Plant Cell Environ. 10.1111/pce.13646