HAPLESS13-Mediated Trafficking of STRUBBELIG Is Critical for Ovule Development in Arabidopsis

Planar morphogenesis,a distinct feature of multicellular organisms,is crucial for the development of ovule,progenitor of seeds. both receptor-like kinases (rlks) such as strubbelig (sub) and auxin gradient mediated by pin-formed1 (pin1) play instructive roles in this process. fine-tuned intercellular communications between different cell layers during ovule development demands dynamic membrane distribution of these cell-surface proteins,presumably through vesicle-mediated sorting. however,the way it’s achieved and the trafficking routes involved are obscure. we report that hapless13 (hap13)-mediated trafficking of sub is critical for ovule development. hap13 encodes the μ subunit of adaptor protein 1 (ap1) that mediates protein sorting at the trans-golgi network/early endosome (tgn/ee). the hap13 mutant,hap13-1,is defective in outer integument growth,resulting in exposed nucellus accompanied with impaired pollen tube guidance and reception. sub is mis-targeted in hap13-1. however,unlike that of pin2,the distribution of pin1 is independent of hap13. genetic interference of exocytic trafficking at the tgn/ee by specifically downregulating hap13 phenocopied the defects of hap13-1 in sub targeting and ovule development,supporting a key role of sporophytically expressed sub in instructing female gametogenesis. © 2016 wang et al.