Fungal symbionts of endangered Crocanthemum canadense (Cistaceae) in Nova Scotia

Abstract

Crocanthemum canadense (L.) Britton (Cistaceae) is critically imperiled in Nova Scotia. The decline of Nova Scotian Crocanthemum canadense is largely due to the loss of the Annapolis Valley sand barrens habitat. Fungal symbionts may aid in nutrient and water acquisition as well as plant defenses. The role of fungal associations with Crocanthemum canadense is unknown; our goal was to identify fungal symbionts to inform ongoing conservation research. We isolated fungi from eighteen Crocanthemum canadense plants collected from Greenwood, Nova Scotia. Using internal transcribed spacer (ITS) rDNA barcoding of fungal cultures, we identified 58 fungal taxa. ITS2 meta-amplicon barcoding of roots and rhizosphere soil revealed 241 fungi with basidiomycetes accounting for 53.8% of reads. Chaetothyriales sp., Mycetinis scorodonius, Acidomelania panicicola, and Scleroderma citrinum were the most abundant root associates based on meta-amplicon data. We quantified percent root colonization of arbuscular mycorrhizal fungi (AMF) using root staining and microscopy. The average AMF colonization rate of the roots was 29.6% (n = 18). Our research provides a foundation for understanding the fungal community in this declining habitat and the first account of fungal symbionts in the above- and below-ground tissues and rhizosphere of Crocanthemum canadense. Identifying fungi influencing endangered Nova Scotian Crocanthemum canadense is valuable for developing conservation strategies.