Stability of the Wheat Seed Mycobiome Across North Carolina’s Longitudinal Gradient

Improving wheat yield and performance involves selecting varieties that are well adapted for a regional area. Although host genotype and environment are major factors that impact crop performance and resilience, less is known about the relative contribution and occurrence of wheat seed endophytic fungal communities across spatial and temporal scales. An increased understanding of composition and assembly of beneficial endophytic fungal communities across regional scales provides valuable insight into the stability of the endophytic seed mycobiome. Our aim in this study was to examine the relative contribution and impact of latitude and longitude gradients within North Carolina (NC) on wheat seed fungal community structure of two regionally adapted soft red winter wheat cultivars, Hilliard and USG 3640. We examined the endophytic wheat seed microbiome of the two winter wheat cultivars planted in official variety trials at five geographic locations across NC in 2021 and two geographic locations in 2022. ITS1 sequence-based analysis of surface disinfested wheat seeds was conducted to determine alpha and beta diversity. Species richness is influenced by geographical location, however wheat seed mycobiome community structure is stable across cultivars and years. Latitude and longitude contributed to the observed variation in wheat seed mycobiome structure, in addition to yield, seed moisture, and leaf nutrients. When surveying taxa present within all cultivars, geographical sites and years, Alternaria and Epicoccum spp. exhibited high relative abundance in the wheat seed mycobiome. Our results provide a comprehensive catalog of core fungal taxa well-adapted to diverse environments and conserved across wheat cultivars.