AUTHOR=Biała-Leonhard Wanda , Zanin Laura , Gottardi Stefano , de Brito Francisco Rita , Venuti Silvia , Valentinuzzi Fabio , Mimmo Tanja , Cesco Stefano , Bassin Barbara , Martinoia Enrico , Pinton Roberto , Jasiński Michał , Tomasi Nicola
TITLE=Identification of an Isoflavonoid Transporter Required for the Nodule Establishment of the Rhizobium-Fabaceae Symbiotic Interaction
JOURNAL=Frontiers in Plant Science
VOLUME=12
YEAR=2021
URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.758213
DOI=10.3389/fpls.2021.758213
ISSN=1664-462X
ABSTRACT=
Nitrogen (N) as well as Phosphorus (P) are key nutrients determining crop productivity. Legumes have developed strategies to overcome nutrient limitation by, for example, forming a symbiotic relationship with N-fixing rhizobia and the release of P-mobilizing exudates and are thus able to grow without supply of N or P fertilizers. The legume-rhizobial symbiosis starts with root release of isoflavonoids that act as signaling molecules perceived by compatible bacteria. Subsequently, bacteria release nod factors, which induce signaling cascades allowing the formation of functional N-fixing nodules. We report here the identification and functional characterization of a plasma membrane-localized MATE-type transporter (LaMATE2) involved in the release of genistein from white lupin roots. The LaMATE2 expression in the root is upregulated under N deficiency as well as low phosphate availability, two nutritional deficiencies that induce the release of this isoflavonoid. LaMATE2 silencing reduced genistein efflux and even more the formation of symbiotic nodules, supporting the crucial role of LaMATE2 in isoflavonoid release and nodulation. Furthermore, silencing of LaMATE2 limited the P-solubilization activity of lupin root exudates. Transport assays in yeast vesicles demonstrated that LaMATE2 acts as a proton-driven isoflavonoid transporter.