||A peptide hormone required for Casparian strip diffusion barrier formation in Arabidopsis roots
Nakayama, Takuya ,
Shinohara, Hidefumi ,
Tanaka, Mina ,
Baba, Koki ,
Ogawa-Ohnishi, MariMatsubayashi, Yoshikatsu
286 , 2017-01 , American Association for the Advancement of Science
Plants achieve mineral ion homeostasis by means of a hydrophobic barrier on endodermal cells called the Casparian strip, which restricts lateral diffusion of ions between the root vascular bundles and the soil. We identified a family of sulfated peptides required for contiguous Casparian strip formation in Arabidopsis roots. These peptide hormones, which we named Casparian strip integrity factor 1 (CIF1) and CIF2, are expressed in the root stele and specifically bind the endodermis-expressed leucine-rich repeat receptor kinase GASSHO1 (GSO1)/SCHENGEN3 and its homolog, GSO2. A mutant devoid of CIF peptides is defective in ion homeostasis in the xylem. CIF genes are environmentally responsive. Casparian strip regulation is not merely a passive process driven by root developmental cues; it also serves as an active strategy to cope with adverse soil conditions.