Pollen tube growth and guidance: Occam's razor sharpened on a molecular arabinogalactan glycoprotein Rosetta Stone. Issue 2 (9th October 2017)

• Record Type: Journal Article
• Authors: Lamport, Derek T. A.; Tan, Li; Held, Michael A.; Kieliszewski, Marcia J.
• Is Part Of: New phytologist. Volume 217:Issue 2(2018)
• Page Start: 491
• Page End: 500
• Publication Date: 2017-10-09
• Subjects: arabinogalactan proteins -- calcium signalling -- cell extension -- Hechtian oscillator -- pectin -- pollen tube tip growth; Botany -- Periodicals; 580
• DOI: 10.1111/nph.14845
• Languages: English
• ISSNs: 0028-646X

Abstract

Summary: Occam's Razor suggests a new model of pollen tube tip growth based on a novel Hechtian oscillator that integrates a periplasmic arabinogalactan glycoprotein–calcium (AGP‐Ca 2+ ) capacitor with tip‐localized AGPs as the source of tip‐focussed cytosolic Ca 2+ oscillations: Hechtian adhesion between the plasma membrane and the cell wall of the growing tip acts as a piconewton force transducer that couples the internal stress of a rapidly growing wall to the plasma membrane. Such Hechtian transduction opens stretch‐activated Ca 2+ channels and activates H + ‐ATPase proton pump efflux that dissociates periplasmic AGP‐Ca 2+ resulting in a Ca 2+ influx that activates exocytosis of wall precursors. Thus, a highly simplified pectic primary cell wall regulates its own synthesis by a Hechtian growth oscillator that regulates overall tip growth. By analogy with the three cryptic inscriptions of the classical Rosetta Stone, the Hechtian Hypothesis translates classical AGP function as a Ca 2+ capacitor, pollen tube guide and wall plasticizer into a simple but widely applicable model of tip growth. Even wider ramifications of the Hechtian oscillator may implicate AGPs in osmosensing or gravisensing and other tropisms, leading us yet further towards the Holy Grail of plant growth.