Cell remodeling and subtilase gene expression in the actinorhizal plant Discaria 2 trinervis highlight host orchestration of intercellular Frankia colonization

JOËLLE FOURNIER; LEANDRO IMANISHI; MIREILLE CHABAUD; ANDREA GENRE; LUKAS BRICHET; LUKAS BRICHET; HERNÁN RAMIRO LASCANO; NACIRA MUÑOZ; ALICE VAYSSIÈRES; ELODIE PIROLLES; LAURENT BROTTIER ; HASSEN GHERBI , ; VALÉRIE HOCHER; SERGIO SVISTOONOFF ; DAVID G. BARKER ; LUIS G. WALL

NEW PHYTOLOGIST

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0028-646X

Nitrogen-fixing filamentous Frankia colonize the root tissues of its actinorhizal host40 Discaria trinervis via an exclusively intercellular pathway. Here we present studies aimed at41 uncovering mechanisms associated with this little-researched mode of root entry, and in42 particular the extent to which the host plant is an active partner during this process.43 ? Detailed characterization of the expression patterns of infection-associated actinorhizal host44 genes has provided valuable tools to identify intercellular infection sites, thus allowing in vivo45 confocal microscopic studies of the early stages of Frankia colonization.46 ? The subtilisin-like serine protease gene Dt12, as well as its Casuarina glauca homologue47 Cg12, are specifically expressed at sites of Frankia intercellular colonization of D. trinervis48 outer root tissues. This is accompanied by nucleo-cytoplasmic reorganisation in the adjacent49 host cells and major remodeling of the intercellular apoplastic compartment.50 ? These findings lead us to propose that the actinorhizal host plays a major role in modifying51 both the size and composition of the intercellular apoplast in order to accommodate the52 filamentous microsymbiont. The implications of these findings are discussed in the light of53 the analogies that can be made with the orchestrating role of host legumes during intracellular54 root hair colonization by nitrogen-fixing rhizobia.