AUTHOR=Billault-Penneteau Benjamin , Sandré Aline , Folgmann Jessica , Parniske Martin , Pawlowski Katharina 

TITLE=Dryas as a Model for Studying the Root Symbioses of the Rosaceae

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.00661

DOI=10.3389/fpls.2019.00661

ISSN=1664-462X

ABSTRACT=<p>The nitrogen-fixing root nodule symbiosis is restricted to four plant orders: Fabales (legumes), Fagales, Cucurbitales and Rosales (Elaeagnaceae, Rhamnaceae, and Rosaceae). Interestingly all of the Rosaceae genera confirmed to contain nodulating species (i.e., <italic>Cercocarpus</italic>, <italic>Chamaebatia</italic>, <italic>Dryas</italic>, and <italic>Purshia</italic>) belong to a single subfamily, the Dryadoideae. The <italic>Dryas</italic> genus is particularly interesting from an evolutionary perspective because it contains closely related nodulating (<italic>Dryas drummondii)</italic> and non-nodulating species (<italic>Dryas octopetala)</italic>. The close phylogenetic relationship between these two species makes <italic>Dryas</italic> an ideal model genus to study the genetic basis of nodulation by whole genome comparison and classical genetics. Therefore, we established methods for plant cultivation, transformation and DNA extraction for these species. We optimized seed surface sterilization and germination methods and tested growth protocols ranging from pots and Petri dishes to a hydroponic system. Transgenic hairy roots were obtained by adapting <italic>Agrobacterium rhizogenes</italic>-based transformation protocols for <italic>Dryas</italic> species. We compared several DNA extraction protocols for their suitability for subsequent molecular biological analysis. Using CTAB extraction, reproducible PCRs could be performed, but CsCl gradient purification was essential to obtain DNA in sufficient purity for high quality <italic>de novo</italic> genome sequencing of both <italic>Dryas</italic> species. Altogether, we established a basic toolkit for the culture, transient transformation and genetic analysis of <italic>Dryas</italic> sp.</p>