Multigenerational drought reveals a stable wheat seed fungal community

The objective of this study revolves around examining the effects of prolonged, post-flowering drought stress on the endophytic fungal community within the seeds of wheat (Triticum spp.) - a crucial global food source. This research endeavor is underpinned by the aim to shed light on how successive generations of wheat cope with drought-induced stress and how the fungal microcosms within the seeds respond to such conditions. Ultimately, the study's significance lies in enhancing our comprehension of legacy drought stress and identifying specific fungi associated with wheat seeds that perform crucial roles under drought circumstances. Our analysis was conducted on three selected winter wheat cultivars - Catawba, Shirley, and USG 3640. We instituted a moderate drought regime on a portion of these wheat plants right after their flowering phase, which was later lifted after one week. The seeds harvested from these first-generation plants were subsequently used for conducting a second round of drought experiments. As we evaluated the effects of post-flowering drought on the physiological parameters of the wheat, we found that plants exposed to drought manifested lower transpiration rates, chlorophyll-a values, and seed yields on a daily basis, validating the effectiveness of our drought implementation. We used ITS1 metabarcoding for analyzing the fungal community in wheat seeds and found a decrease in species richness under post-flowering drought stress in both generations. Additionally, the generational factor was found to account for differences in fungal species richness and community structure, independently of the drought treatment. The most consistently abundant fungal taxa across all cultivars, treatments, and generations were Cladosporium, Penicillium, Alternaria, and Epicoccum. Overall, our findings corroborate the hypothesis that post-flowering drought stress significantly influences the fungal community within wheat seeds.