Plant symbiosis with arbuscular mycorrhizal (AM) fungi provides many benefits, including increased nutrient uptake, drought tolerance, and belowground pathogen resistance. To develop a better understanding of the genetic architecture of mycorrhizal symbiosis, we conducted a genome-wide association study (GWAS) of this plant-fungal interaction in cultivated sunflower. A diversity panel of cultivated sunflower (Helianthus annuus L.) was phenotyped for root colonization under inoculation with the AM fungus Rhizophagus intraradices. Using a mixed linear model approach with a high-density genetic map, we identified genomic regions that are likely associated with R. intraradices colonization in sunflower. Additionally, we used a set of twelve diverse lines to assess the effect that inoculation with R. intraradices has on dried shoot biomass and macronutrient uptake. Colonization amongst lines in the mapping panel ranged from 0-70% and was not correlated with mycorrhizal growth response, shoot phosphorus response, or shoot potassium response among the Core 12 lines. Association mapping yielded three single nucleotide polymorphisms (SNPs) that were significantly associated with R. intraradices colonization. This is the first study to use GWAS to identify genomic regions associated with AM colonization in an Asterid eudicot species. Three genes of interest identified from the regions containing these SNPs are likely related to plant defense.

See full text of the article and associated metadata. The presented data are metrics of root colonization by the arbuscular mycorrhizal fungus Rhizophagus intraradices assessed in 288 inbred lines of sunflower in a greenhouse experiment. Data on shoot biomass and nutrient content in a subset of lines is also presented.

DataS1:
Root colonization data used for genome-wide association mapping.

DataS2:
Above-ground dry biomass and nutrient concentrations in dried plant tissues, measured
using Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) for the Core 12 lines.

DataS3:
List of all genes within significant and suggestive regions.

Supplemental Information:
Dataset legends, supplemental figures, and supplemental methods.