Research Scientist Iowa State University Ames, Iowa
Body of Abstract: Heat stress is one of the major limiting factors for soybean productivity worldwide. Recent research has highlighted microbes crucial role in helping plants adapt to heat stress. Microbes modulate hormone levels, enhance nutrient uptake, induce stress-responsive genes (induced systemic resistance), improve soil health, and ultimately, protect the plants from enemies by forming biofilm in and around the rhizosphere. Therefore, our objective was to understand the role of native soil microbes in heat tolerance adaptation through 16S and ITS sequencing and develop an understanding of key genes, metabolites, and root anatomical traits in soybean. The experiment was conducted with four contrasting soybean genotypes (Williams 82, IAS 19C3, PI 639693, and PI 89008) for heat stress tolerance with (non-autoclaved) and without (autoclaved) microbes under high (day: 38o C for 16 hrs and dark: 28o C for 8 hrs) and optimum (day: 28o C for 16 hrs and dark: 21o C for 8 hrs) temperatures with 60% relative humidity and current ambient CO2 levels (400 ppm). Autoclaving did not change the physical properties of the soil, but the chemical property was affected. We have observed significant respiration differences between autoclaved and non-autoclaved soils; non-autoclaved soils showed a fourfold cumulative CO2 flux difference compared to autoclaved soils. The high-quality rhizospheric soil DNA was used for 16S (bacteria) and ITS (fungi) library preparation and MiSeq sequencing. Alpha and beta diversity revealed significant differences between the treatments. Higher bacterial abundance was observed at optimum temperature with microbes treatment. Pseudomonadaceae species were abundant across the treatments. Genotype-specific bacterial abundance was also observed across the treatments. Our study will help holistically understand the heat and microbial interactions to breed soybean cultivars for wider adaptation to variable future climatic conditions.