Co-occurrence Networks and Topological Analyses Revealed Microbiome Structures in Soybean Roots from a Louisiana Soybean Field Severely Damaged by Prolonged High Temperatures and Drought Stress

Drought stress has a significant impact on agricultural productivity, affecting key crops such as soybeans, the second most widely cultivated crop in the United States. We conducted endophytic and rhizospheric microbial diversity analyses in soybean plants cultivated during the 2023 growing season, amid extreme weather conditions of prolonged high temperatures and drought in Louisiana. Specifically, we collected surviving and non-surviving soybean plants from two plots of a Louisiana soybean field severely damaged from the extreme heat and drought condition in 2023. We did not observe any significant difference in the microbial diversity of rhizosphere between surviving and non-surviving plants. However, we found obvious differences in the structure of endophytic microbial community in root tissues between the two plant conditions. Especially, the bacterial genera of Proteobacteria, Pseudomonas and Pantoea, were predominant in the surviving root tissues, while the bacterial genus Streptomyces was conspicuously dominant in the non-surviving (dead) root tissues. Co-occurrence patterns and network centrality analyses enabled us to discern the intricate characteristics of operational taxonomic units (OTUs) within endophytic and rhizospheric networks. Overall, this study advances our understanding of the intricate relationship between bacteria and plants under drought stress, paving the way for future research to investigate the importance of microbial diversity in drought affected regions such as Louisiana.