Abstract Detail

Pteridology

Eily, Ariana [1], Pryer, Kathleen M. [1], Li, Fay-Wei [2].

A glimpse at genes critical to the Azolla-Nostoc symbiosis.

Azolla is a genus of small aquatic ferns with a vast potential to benefit the environment and agriculture, as well as provide insight into the evolution of plant-cyanobacterial symbioses. Azolla has this capability because it houses a nitrogen-fixing cyanobacterial symbiont, Nostoc azollae, in each of its leaves. These two partners have been co-evolving for nearly 100 million years. Each Azolla leaf cavity houses N. azollae within a mucilaginous matrix. These cavities are equipped with specialized trichomes for exchanging signals and nutrients with the cyanobiont. This intimate symbiosis is unique because Nostoc is present for the entire life cycle of the fern––it is passed down through generations (much like mitochondria) during sexual reproduction. Though we know that this symbiosis enables the exchange of ammonium and sucrose between these partners, we have, until recently, been unable to determine the underlying molecular mechanisms that make this symbiosis so successful. The recently sequenced and annotated genome of Azolla filiculoides has allowed us to compare gene expression profiles of Azolla, both with and without its cyanobiont, using RNA-sequencing and gene ontology analysis to uncover genes relevant to the Azolla-Nostoc symbiosis. We identified distinct expression patterns based on the presence or absence of Nostoc, and more than 100 genes had significant differential expression patterns relevant to the symbiosis. Among them, we determined genes of transport proteins for ammonium and metal ions, as well as genes for the biosynthesis of flavonoids. We hypothesize that these genes may be “putative symbiosis genes,” and are eager to explore their significance in this symbiosis, as well as learn what they may tell us about other plant-cyanobacterial symbioses.

1 - Duke University, Biology, 130 Science Dr., Durham, NC, 27708, USA
2 - Cornell University, Boyce Thompson Institute, Ithaca, NY, 14853, USA

Keywords:
symbiosis
Plant-cyanobacteria interactions
ferns
Nostoc
transcriptomics.

Presentation Type: Oral Paper
Session: 15, Pteridology II
Location: 108/Mayo Civic Center
Date: Monday, July 23rd, 2018
Time: 4:45 PM
Number: 15005
Abstract ID:601
Candidate for Awards:Edgar T. Wherry award